GItract.pptx

GASTROINTESTINAL TRACT
BY DR. N.VAJIKHA SAPHRIN B.S.M.S., DIP(HIJAMA)

INTRODUCTION
• Digestion is defined as the process by which food is broken down into simple chemical
substances that can be absorbed and used as nutrients by the body.
• Most of the substances in the diet cannot be utilized as such.
• These substances must be broken into smaller particles, so that they can be absorbed into blood
and distributed to various parts of the body for utilization.
• Digestive system is responsible for these functions.
• Digestive process is accomplished by mechanical and enzymatic breakdown of food into simpler
chemo call compounds.
• A normal young healthy adult consumes about 1 kg of solid diet and about 1 to 2 litter of liquid
diet every day.
• All these food materials are subjected to digestive process, before being absorbed into blood and
distributed to the tissues of the body.
• Digestive system plays the major role in the digestion and absorption of food substances.

FUNCTIONS OF DIGESTIVE SYSTEM :
• 1. Ingestion or consumption of food substances
• 2. Breaking them into small particles
• 3. Transport of small particles to different areas of the digestive tract
• 4. Secretion of necessary enzymes and other subs trances for digestion
• 5. Digestion of the food particles
• 6. Absorption of the digestive products (nutrients)
• 7. Removal of unwanted substances from the body.

FUNCTIONAL ANATOMY OF DIGESTIVE SYSTEM
• Digestive system is made up of gastrointestinal tract (GI tract) or
• alimentary canal and accessory organs,
• which help in the process of digestion and absorption.
• Gal tract is a tubular structure extending from the mouth up to anus, with a length of about
30 feet.
• It opens to the external environment on both ends. GI tract is formed by two types of
organs:
• 1. Primary digestive organs.
• 2. Accessory digestive organs.

1. PRIMARY DIGESTIVE ORGANS
• Primary digestive organs are the organs where actual digestion takes place.
• Primary digestive organs are:
• I. Mouth
• ii. Pharynx
• iii. Esophagus
• iv. Stomach
• V. Small intestine
• vi. Large intestine.

2. ACCESSORY DIGESTIVE ORGANS
• Accessory digestive organs are those which help prim army digestive organs in the
process of digestion.
• Accessory digestive organs are:
• i. Teeth
• ii. Tongue
• iii. Salivary glands
• iv. Exocrine part of pancreas
• V. Liver
• vi. Gallbladder.

■ 1. MUCUS LAYER
• Mucus layer is the innermost layer of the wall of GI tract.
• It is also called gastrointestinal mucosa or mucus membrane.
• It faces the cavity of GI tract.
• Mucosa has three layers of structures:
• 1. Epithelial lining
• 2. Lamina propria
• 3. Muscularis mucosa.

EPITHELIAL LINING
• Epithelial lining is in contact with the contents of GI tract.
• The type of cells in this layer varies in different parts of GI tract.
• The inner surface of mouth,
• surface of tongue,
• inner surface of pharynx and
• oesophagus have stratified squamous epithelial cells.
• However, mucus membrane lining the other parts such as stomach,
• small intestine and large intestine has columnar epithelial cells.

LAMINA PROPRIA AND MUSCULARIS MUCOSA
• Lamina Propria
• Lamina propria is formed by connective tissues,
• which contain fibroblasts,
• macrophages,
• lymphocytes and eosinophils.
• Muscularis Mucosa
• Muscularis mucosa layer consists of a thin layer of smooth muscle fibers.
• It is absent in mouth and pharynx.
• It is present from oesophagus onwards.

2. SUBMUCUS LAYER
• Submucous layer is also present in all parts of GI tract,
• except the mouth and pharynx.
• It contains loose collagen fibers,
• elastic fibers,
• reticular fibers and
• few cells of connective tissue.
• Blood vessels,
• lymphatic vessels and
• nerve plexus are present in this layer.

3. MUSCULAR LAYER
• Muscular layer in lips, cheeks and wall of pharynx contains skeletal muscle fibers.
• The oesophagus has both skeletal and smooth muscle fibers.
• Wall of the stomach and intestine is formed by smooth muscle fibers.
• Smooth muscle fibers in stomach are arranged in three layers:
• I. Inner oblique layer
• ii. Middle circular layer
• iii. Outer longitudinal layer.

• Smooth muscle fibers in the intestine are arranged in two layers:
• Inner circular layer
• Outer longitudinal layer.
• Auerbach nerve plexus is present in between the circular and longitudinal
muscle fibers.
• The smooth muscle fibers present in inner circular layer of anal canal constitute
internal anal sphincter.
• The external anal sphincter is formed by skeletal muscle fibers

4. SEROUS OR FIBROUS LAYER
• Outermost layer of the wall of GI tract is either serous or fibrous in nature.
• The serous layer is also called serosa or serous membrane and it is formed by
connective tissue and myoepithelial cells.
• It covers stomach, small intestine and large intestine.
• The fibrous layer is otherwise called fibrosa and it is formed by connective tissue.
• It covers pharynx and oesophagus.

ORAL CAVITY
• The oral cavity (month);
• Buccal cavity
• is the first part of digestive tube.
• It extends anteroposteriorly from lips to the
oropharyngeal isthmus,
• commonly used for ingestion of food and fluid.
• Isthmus, commonly used for indigestion of food
and fluid.
• Its divided into two parts;
• 1. A smaller slit-like space between lips/cheeks
and teeth gingivae gums called vestibule.
• 2. A larger space inside the teeth and gums

VESTIBULE OF THE MOUTH
• The vestibule of the mouth is a narrow Space that lies outside the
teeth and gums,
• and inside the lips and cheeks.
• It is limited above and below by the reflection of mucus membrane
from the lips and cheeks to the gums.
• When the mouth is open,
• it freely communicates with the oral cavity proper but when it is
closed,
• i.e., when the teeth are occluded.
• It communicates on each side with the oral cavity proper through a
small gap behind the third molar called retromolar region.
• Except teeth the entire vestibule is lined by mucus membrane.

• The lateral wall of the vestibule is formed by check made up of buccinator muscle.
• The tone of buccinator muscle Arnd muscles of lips keep the wall of the vestibule in contact with the
teeth and gums.
• In facial palsy, due to paralysis of these muscles, the lips and cheeks fall away from the teeth and
gums, and
• food tends to collect in the vestibule of the Mouth.
• The openings in the vestibule of the mouth are as follows:
• 1. Opening of parotid duct; the parotid duct opens into the vestibule opposite the crown of the
upper second molar tooth.
• 2. Openings of labial and buccal mucus glands.
• 3. Openings of 1 or 5 molar glands mucus situates on the buccopharyngeal fascia.

FUNCTIONS OF MOUTH
• Primary function of mouth is eating and it has few other important functions also.
• Functions of mouth include:
• 1. Ingestion of food materials
• 2. Chewing the food and mixing it with saliva
• 3. Appreciation of taste of the food
• 4. Transfer of food (bolus) to the oesophagus by swallowing
• 5. Role in speech
• 6. Social functions such as smiling and other expressions.

LIPS
• lips are two mobile musculofibrous folds that surround the opening of the mouth.
• The upper and lower lips meet laterally at an angle of the mouth,
• usually in front of Frist premolar tooth.
• The lips are lined externally by the skin and internally by the mucus membrane
• The mucocutaneous junction lines the edge of the lip.
• only a part of the mucosal surface is normally seen.
• The red portion of lip is called vermillion zone,
• the rad hue is due to rich vascular bed visible through the thin moist epithelium.
• The skin and vermillion zone meet at the vigintillion border.
• The internal aspect of each lip is connected lo the corresponding gun by a median fold of the
mucus membrane called frenulum of the lips.

STRUCTURE
1.Skin.
2.2. Superficial fascia.
3.3. Orbicularis orris muscle.
4.4. Submucosa containing mucus glands.
5.5. Mucus membrane.

Blood Vessels
Each lip is supplied by labial branches of facial artery.
Each lip has an arterial arch formed by the end-on anastomosis
Between labial branches of the facial arteries
. When this arterial arch is cut, blood spurts from both ends with equal force. The veins correspond to the arteries
and drain into the facial vein.
Lymphatics
The lymphatics from the central part of the lower lip drain into submental lymph nodes. The lymphatics from lateral
parts of lower lip and whole of upper lip drain into submandibular lymph nodes.
Nerve Supply
The lips have rich sensory supply from trigeminal nerve
. The upper lip is supplied by labial branches of the infraorbital nerve (a branch of maxillary division) and
lower lip by the mental nerve (a branch of mandibular division of the trigeminal nerve),
The red portions of lip are highly sensitive and represented by a large area in the sensory cortex of cerebral
hemisphere. Nerve block.

CHEEKS
• The cheeks are fleshy flaps forming a large part of the face.
• Each cheek is continuous in front with the lip.
• The junction between the two is marked by the nasolabial sulcus or the nasolabial furrow,
• which extends from the side of the nose the teeth to their sockets.
• To the angle of the mouth. Like the lips, the cheeks are lined externally by the skin and internally by the
mucus membrane.
• Layers of the Cheek From superficial to deep, the layers of the cheek are as follows:
• 1, Skin.
• 2. Superficial fascia containing some muscles of facial expression, viz. zygomaticus major, risorius.
• 3. Buccal pad of fat.
• 4. Buccopharyngeal fascia.
• 5. Buccinator muscle between the alveolar processes of (a) the labial aspect is supplied by buccal branch of
both jaws.
• 6. Submucosa containing buccal (mucus) glands.
• 7. Mucus membrane.
• The last five layers of the cheek are pierced by the parotid duct. The lymphatics from cheek drain into the

MUCUS LINING OF THE CHEEK
• The inner aspect of the cheek is lined by stratified squamous epithelium.
• It is pierced by parotid duct opposite the maxillary upper molar tooth at a small parotid papilla.
• A hyper keratinized line (the linea alba) may be seen at a position related to the occlusal plane of
the teeth.
• Clinical correlation
• In the retromolar region a fold of mucus membrane containing pterygomandibular raphe
extends between the upper and lower alveoli.
• The entrance to the pterygomandibular space,
• which contains inferior alveolar and lingual nerves,
• lies lateral to pterygomandibular fold and medial to the ridge produced by sile for injection of
anesthetic agent in inferior alveolar.

GUMS (GINGIVA)
• The gums are composed of fibrous tissue covered with a
smooth vascular mucous membrane.
• They envelop the alveolar processes of the jaws and the
necks of the teeth.
• At the necks of the teeth,
• the fibrous tissue of gum becomes continuous with the
periodontal membrane,
• which attaches the teeth to their sockets.

The gum/gingiva has three parts,
1. Free part (free gingiva), which surrounds the neck of tooth like a collar.
2. Structure The cheek is largely composed of buccinator muscle,
3. In addition, it contains buccal glands, blood vessels, and nerves, The
buccinator muscle is covered by buccopharyngeal fascia.
4. The buccal pad of fat is best developed in infants, overlies the
buccopharyngeal fascia and extends posteriorly deep to masseter muscle.
5. Attached part (attached gingiva), which is firmly attached to the alveolar
process.
6. Interdental part (interdental gingiva), which is the extension of the attached
gingiva between the teeth.
PARTS OF GUM

Nerve Supply
Upper gums on:
(a) the labial aspect is supplied by the posterior, middle, and anterior-superior alveolar
nerves.
(b) the lingual aspect is supplied by the greater palatine and nasopalatine nerves.
Lower gums on:
(a) the labial aspect is supplied by buccal branch of mandibular nerve, and incisive branch
of mental nerve, and
(b) the lingual aspect is supplied by the lingual nerves,
Lymphatic Drainage
Upper gums:
The lymphatics from upper gums drain into submandibular lymph nodes.
. Lower gums:
The lymphatics from anterior part (i.e., gums of lower central incisors) drain into submental
lymph nodes while those from remaining part drain into submandibular lymph nodes.

CLINICAL CORRELATION
• GINGIVITIS
• The improper oral hygiene may cause inflammation of
gums (gingivitis) and
• suppuration with formation of pockets of pus between
teeth and gums leading to clinical condition called
pyorrhoea,
• which clinically present as
• (a) discharge of pus at the margins of gums and
• (b) foul smell during breathing.

SCURVY
• • Scurvy: In scurvy
due to deficiency of
vitamin C
• the gums become
swollen,
• spongy, and
• bleed on touch.

TEETH
• The teeth are mineralized bone-like
• structures projecting from the
alveolar processes of the jaws.
• The study of teeth,
• strictly speaking,
• forms the subject of odontology
whereas the science consumed with
the diagnosis and treatment of
diseases of the teeth and associated
structures is called dentistry
• (dens, dentis = tooth).

NUMBER OF TEETH
• In an adult there are 16 permanent teeth in each jaw.
• The humans are diphyodont,
• i.e., two sets of teeth develop in a person's lifetime.
• The first set of teeth is primary or deciduous teeth.
• They begin to form prenatally about 14 weeks in intrauterine life and completed postnatally at about 3
years of age.
• The deciduous teeth remain intact up to about 6 Clinical correlation Eruption of teeth:
• The time of eruption of the teeth is a useful stepping stone in a child's development.
• The time of eruption is also important in for neck medicine to estimate the age at the time of death from
the skeletonized remains as a rough guide.
• The time of eruption of teeth can be thought of in 6' or multiples of '6'as follows: -
• 1st lower deciduous incisor appears at: 6 months. –
• All the deciduous teeth complete eruption by: 24 months
• Permanent 1st molar appears at: 6 years.

• -Permanent 1st incisor appears at: 6 years.
• Permanent 2nd molar appears at: 12 years.
• - Permanent 3rd molar appears at: 18-24 years.
• years of age. At about that time the permanent teeth begin to erupt in the mouth.
• The first of milk teeth (lower central incisors) erupt approximately 6 months after birth and
the last (second milk molars) at approximately 2 years.
• The first permanent tooth (first molar) erupts at approximately 6 years and continues until
about 17 years of age.
• The wisdom teeth are less predictable and if they do erupt,
• it is between the ages 17 and 25.
• Because jaws are formed by this time and other teeth have already well-occupied their place,
the eruption of wisdom teeth may fail to occur properly causing a clinical condition called
impaction of tooth

ERUPTION OF DECIDUOUS TEETH
• The deciduous teeth begin to erupt at about 6 months and all are erupted by the end of 2nd
year (or soon after)
• The teeth of lower jaw erupt somewhat before the corresponding teeth in the upper jaw.
• The approximate age of eruption of deciduous teeth is as follows:
• • Lower central incisors: 6 months
• Upper central incisors: 7 months
• Lateral incisors: 8-9 months
• First molar: 12 months (1 year)
• Canines: 18 months (1 year 6 months)
• Second molars: 24 months (2 years)

ERUPTION OF PERMANENT TEETH
• The permanent teeth begin to erupt at about 6 years and all get erupted by 18–24
years. The approximate age of eruption of permanent teeth is as follows:
• • First molar: 6 years
• • Medial incisors: 7 yearsLateral incisors: 8 years attack.
• • First premolar: 9 years
• • Second premolar: 10 years
• • Canines: 11 years
• • Second molars: 12 years
• • Third molar (Wisdom tooth): 18-24 years

PARTS OF A TOOTH
• Each tooth has three parts:
• 1 A crown, projecting above or below the gum.
• 2 A root, embedded in the jaw beneath the gum.
• 3 A neck, between the crown and root and surrounded by the gum.

STRUCTURE
• Structurally, each tooth is composed of:
• 1 The pulp in the center
• 2 The dentine surrounding the pulp.
• 3 The enamel covering the projecting part of dentine, or crown.
• 4 The cementum surrounding the embedded part of the dentine.
• 5 The periodontal membrane.

BLOOD AND NERVE SUPPLY OF TEETH
• Blood supply of teeth –
• Both upper and lower are supplied by branches of maxillary artery.
• Nerve Supply of Teeth
• The pulp and periodontal membrane have the same nerve supply which is as
follows:
• The upper teeth are supplied by the posterior superior alveolar, middle superior
alveolar, and the anterior superior alveolar nerves (maxillary nerve).
• The lower teeth are supplied by the inferior alveolar nerve (mandibular nerve)
Sensory root Ophthalmic Trigeminal ganglion Maxillary nerve Mandibular nerve
Inferior alveolar nerve

FORM AND FUNCTION (CROWNS AND ROOTS)
• 1 The shape of a tooth is adapted to its function.
• The incisors are cutting teeth, with chisel - like crowns.
• The upper and lower incisors overlap each other like the blades of a pair of scissors.
• The canines are holding and tearing teeth, with conical and rugged crowns.
• These are better developed in carnivores.
• Each premolar has two cusps and is, therefore, also called a bicuspid tooth.
• The molars are grinding teeth, with square crowns, bearing four or five cusps on their crowns.
• The incisors, canines and premolars have single roots, with the exception of the first upper premolar which has a bifid root.
• The upper molars have three roots, of which two are lateral and one I the lower molars have only two roots, a and a posterior
.and a posterior.
• Eruption of Teeth The deciduous teeth begin to erupt at about the sixth month, and all get erupted by the end of the second
year or soon after.
• The teeth of the lower jaw erupt slightly earlier than those of the upper jaw.

FUNCTIONS OF TEETH
• 1. Incise and grind the food material during mastication.
• 2. Perform (sometimes) the role of weapon for defence or attack.
• 3. Provide beauty to the face and means for facial expression.

CLINICAL ANATOMY
• ● Being the hardest and chemically the most stable tissues in the body,
• the teeth are selectively preserved after death and may be fossilized.
• Because of this, the teeth are very helpful in medicolegal practice for
identification of otherwise unrecognizable dead bodies.
• The teeth also provide by far the best data to study evolutionary changes and the
relationship between ontogeny and phylogeny.

IMPROPER ORAL HYGIENE
• may cause gingivitis and suppuration with pocket formation between the teeth and
gums.
• This results in a chronic pus discharge at the margin of the gums.
• The condition is known as pyorrhea alveolar is (chronic periodontitis).
• Pyorrhea is common cause of foul breath for which the patient hardly ever consults a
dentist because the condition is painless.
• Decalcification of enamel and dentine with consequent softening and gradual
destruction of the tooth is known as dental caries.
• A caries tooth is tender on mastication.
• Infection of apex of root (apical abscess) occurs only when the pulp is dead. The
condition can be recognized in a good radiograph.

IRREGULAR DENTITION
• is common in rickets and the upper permanent incisors may be notched,
• the notching corresponds to a small segment of a large circle.
• In congenital syphilis, also the same teeth are notched, but the notching
corresponds to a large segment of a small circle
• (Hutchinson’s 228 The third molar teeth also called wisdom teeth usually erupt
between 18 and 20 years.
• These may not erupt normally due to less space and may get impacted causing
enormous pain.

EYE TEETH
• • The upper canine teeth are called as the “eye teeth “as these have long roots
which reach up to the medial angle of the eye.
• Infection of these roots may spread in the facial vein and even lead to
thrombosis of the cavernous sinus.

• • The upper teeth need separate injections of the anaesthetic on both the buccal
and palatal surfaces of the maxillary process just distal to the tooth.
• The thin layer of bone permits rapid diffusion of the drug up to the tooth
• • Time of eruption of the teeth helps in assessing the age of the person.

■ SALIVARY GLANDS
• In humans, the saliva is secreted by three pairs of major (larger) salivary glands
and some minor (small) salivary glands.
• ■ MAJOR SALIVARY GLANDS
• Major glands are:
• 1. Parotid glands
• 2. Submaxillary or submandibular glands
• 3. Sublingual glands.

■ MINOR SALIVARY GLANDS
• 1. Lingual Mucus Glands Lingual mucus glands are situated in posterior one third of the tongue,
behind circumvallate papillae and at the tip and margins of tongue.
• 2. Lingual Serous Glands Lingual serous glands are located near circumvallate papillae and filiform
papillae.
• 3. Buccal Glands Buccal glands or molar glands are present between the mucus membrane and
buccinator muscle.
• Four to five of these are larger and situated outside buccinator, around the terminal part of parotid
duct.
• 4. Labial Glands Labial glands are situated beneath the mucus membrane around the orifice of
mouth.
• 5. Palatal Glands Palatal glands are found beneath the mucus membrane of the soft palate.

CLASSIFICATION OF SALIVARY GLANDS
• Salivary glands are classified into three types, based on the type of secretion:
• 1. Serous Glands Serous glands are mainly made up of serous cells.
• These glands secrete thin and watery saliva. Parotid glands and lingual serous glands are the
serous glands.
• 2. Mucus Glands Mucus glands are mainly made up of mucus cells.
• These glands secrete thick, viscous saliva with high mucin content.
• Lingual mucus glands, buccal glands and palatal glands belong to this type.
• 3. Mixed Glands Mixed glands are made up of both serous and mucus cells.
• Submandibular, sublingual and labial glands are the mixed glands.

STRUCTURE AND DUCT SYSTEM OF SALIVARY GLANDS
• Salivary glands are formed by acini or alveoli.
• Each acinus is formed by a small group of cells which surround a central globular cavity.
• Central cavity of each acinus is continuous with the lumen of the duct.
• The fine duct draining each acinus is called intercalated duct.
• Many intercalated ducts join together to form intralobular duct.
• Few intralobular ducts join to form interlobular ducts, which unite to form the main duct of the
gland.
• A gland with this type of structure and duct system is called racemose type (racemose = bunch of
grapes).

1. PAROTID GLANDS
• Parotid glands are the largest of all salivary glands, situated at the side of the face
just below and in front of the ear.
• Each gland weighs about 20 to 30 g in adults.
• Secretions from these glands are emptied into the oral cavity by Steensen duct.
• This duct is about 35 mm to 40 mm long and opens inside the cheek against the
upper second molar tooth.

SUBMAXILLARY GLANDS
• Submaxillary glands or submandibular glands are located in submaxillary triangle,
medial to mandible.
• Each gland weighs about 8 to 10 g.
• Saliva from these glands is emptied into the oral cavity by Wharton duct, which is
about 40 mm long.
• The duct opens at the side of frenulum of tongue, by means of a small opening
on the summit of papilla called carunculate sublingual is.

SUBLINGUAL GLANDS
• Sublingual glands are the smallest salivary glands situated in the mucosa at the floor
of the mouth.
• Each gland weighs about 2 to 3 g.
• Saliva from these glands is poured into 5 to 15 small ducts called ducts of Rivinus.
• These ducts open on small papillae beneath the tongue.
• One of the ducts is larger and it is called Bartholin duct.
• It drains the anterior part of the gland and opens on carunculate sublingual is near the
opening of submaxillary duct.

PROPERTIES AND COMPOSITION OF SALIVA
• ■ PROPERTIES OF SALIVA
• 1. Volume: 1000 mL to 1500 mL of saliva is secreted per day and it is approximately about 1 mL / minute.
• Contribution by each major salivary gland is:
• I. Parotid glands: 25 %
• ii. Submaxillary glands: 70 %
• iii. Sublingual glands: 5 %.
• 2. Reaction:
• Mixed saliva from all the glands is slightly acidic with
• pH of 6.35 to 6.85 3. Specific gravity:
• It ranges between 1.002 and 1.012.
• Tonicity: Saliva is hypotonic to plasma.
■ COMPOSITION OF SALIVA
Mixed saliva contains
99.5 % water and
0.5 % solids.

FUNCTIONS OF SALIVA
• Saliva is a very essential digestive juice. Since it has many functions, its absence
leads to many inconveniences.
• 1. PREPARATION OF FOOD FOR SWALLOWING
• 2. APPRECIATION OF TASTE
• 3. DIGESTIVE FUNCTION
• 4. CLEANSING AND PROTECTIVE FUNCTIONS
• 5.ROLE IN SPEECH
• 6.REGULATION OF SALIVARY SECRETION

1. PREPARATION OF FOOD FOR SWALLOWING AND
■ 2. APPRECIATION OF TASTE
• ■ 1. PREPARATION OF FOOD FOR SWALLOWING
• When food is taken into the mouth, it is moistened and dissolved by saliva.
• The mucus membrane of mouth is also moistened by saliva. It facilitates chewing.
• By the movement of tongue, the moistened and masticated food is rolled into a bolus.
• Mucin of saliva lubricates the bolus and facilitates swallowing.
• ■ 2. APPRECIATION OF TASTE
• Taste is a chemical sensation.
• By its solvent action, saliva dissolves the solid food substances, so that the dissolved substances can
stimulate the taste buds.
• The stimulated taste buds recognizes the taste.

DIGESTIVE FUNCTION
• Saliva has three digestive enzymes, namely salivary amylase, maltase and lingual lipase.
• Salivary Amylase Salivary amylase is a carbohydrate - digesting (amylolytic) enzyme.
• It acts on cooked or boiled starch and converts it into dextrin and maltose.
• Though starch digestion starts in the mouth, major part of it occurs in stomach because, food stays only for a short time in the mouth.
• Optimum pH necessary for the activation of salivary amylase is.
• Salivary amylase cannot act on cellulose.
• Maltase
• Maltase is present only in traces in human saliva and it converts maltose into glucose.
• Lingual Lipase Lingual lipase is a lipid - digesting (lipolytic) enzyme.
• It is secreted from serous glands situated on the posterior aspect of tongue.
• It digests milk fats (pre-emulsified fats).
• It hydrolyses triglycerides into fatty acids and diacylglycerol.

CLEANSING AND PROTECTIVE FUNCTIONS
• Due to the constant secretion of saliva, the mouth and teeth are rinsed and kept free off food debris, shed
epithelial cells and foreign particles.
• In this way, saliva prevents bacterial growth by removing materials, which may serve as culture media for the
bacterial growth.
• ii. Enzyme lysozyme of saliva kills some bacteria such as staphylococcus, streptococcus and brucella.
• iii. Proline - rich proteins present in saliva posses’ antimicrobial property and neutralize the toxic substances
such as tannins. Tannins are present in many food substances including fruits.
• Iv. Lactoferrin of saliva also has antimicrobial property.
• v. Proline – rich proteins and lactoferrin protect the teeth by stimulating enamel formation.
• vi. Immunoglobulin IgA in saliva also has antibacterial and antiviral actions.
• vii. Mucin present in the saliva protects the mouth by lubricating the mucus membrane of mouth.

ROLE IN SPEECH AND EXCRETORY FUNCTION
• ROLE IN SPEECH
• By moistening and lubricating soft parts of mouth and lips, saliva helps in speech.
• If the mouth becomes dry, articulation and pronunciation become difficult.
• EXCRETORY FUNCTION
• Many substances, both organic and inorganic, are excreted in saliva.
• It excretes substances like mercury, potassium iodide, lead, and thiocyanate.
• Saliva also excretes some viruses such as those causing rabies and mumps.
• In some pathological conditions, saliva excretes certain substances, which are not found in saliva under normal conditions.
• Example is glucose in diabetes mellitus.
• In certain conditions, some of the normal constituents of saliva are excreted in large quantities. For example, excess urea is
excreted in saliva during nephritis and excess calcium is excreted during hyperparathyroidism.

• REGULATION OF BODY TEMPERATURE
• In dogs and cattle, excessive dripping of saliva during panting helps in the loss of heat and regulation of
body temperature.
• However, in human beings, sweat glands play a major role in temperature regulation and saliva does not
play any role in this function.
• REGULATION OF WATER BALANCE
• When the body water content decreases, salivary secret ton also decreases.
• This causes dryness of the mouth and induces thirst.
• When water is taken, it quenches the thirst and restores the body water content.
• 1REGULATION OF SALIVARY SECRETION
• Salivary secretion is regulated only by nervous mech anis.
• Autonomic nervous system is involved in the regulation of salivary secretion.

■ NERVE SUPPLY TO SALIVARY GLANDS
• Salivary glands are supplied by both parasympathetic and sympathetic divisions of autonomic nervous
system.

REFLEX REGULATION OF SALIVARY SECRETION
• Salivary secretion is regulated by nervous mechanism through reflex action.
• Salivary reflexes are of two types:
• 1. Unconditioned reflex.
• 2. Conditioned reflex.

1. UNCONDITIONED REFLEX AND CONDITIONED REFLEX
• Unconditioned Reflex
• Unconditioned reflex is the inborn reflex that is present since birth.
• It does not need any previous experience.
• This reflex induces salivary secretion when any substance is placed in the mouth.
• It is due to the stimulation of nerve endings in the mucus membrane of the oral cavity.
• Conditioned Reflex
• Conditioned reflex is the one that is acquired by experience and it needs previous experience.
• Presence of food in the mouth is not necessary to elicit this reflex.
• The stimuli for this reflex are the sight, smell, hearing or thought of food.
•

EFFECT OF DRUGS AND CHEMICALS ON SALIVARY SECRETION
• Substances which increase salivary secretion
• 1. Sympathomimetic drugs like adrenaline and ephedrine.
• 2. Parasympathomimetic drugs like acetylcholine, pilocarpine, muscarine and physostigmine.
• 3. Histamine.
• Substances which decrease salivary secretion
• 1. Sympathetic depressants like ergotamine and dienamine.
• 2. Parasympathetic depressants like atropine and scopolamine.
• 3. Anesthetics such as chloroform and ether stimulate the secretion of saliva.
• However, deep anesthesia decreases the secretion due to central inhibition.

APPLIED PHYSIOLOGY
■ HYPOSALIVATION
• HYPOSALIVATION
• Reduction in the secretion of saliva is called hyposalivation. It is of two types, namely temporary
hyposalivation and permanent hyposalivation.
• 1. Temporary hyposalivation occurs in:
• I. Emotional conditions like fear.
• Ii. Fever.
• iii. Dehydration.
• 2. Permanent hyposalivation occurs in:
• I. Sialolithiasis (obstruction of salivary duct).
• ii. Congenital absence or hypoplasia of salivary glands.
• iii. Bell palsy (paralysis of facial nerve).

■ HYPERSALIVATION
• Excess secretion of saliva is known as hypersalivation.
• Physiological condition when hypersalivation occurs is pregnancy.
• Hypersalivation in pathological conditions is called ptyalism, sialorrhea, asialism or dialysis.
Hypersalivation occurs in the following pathological conditions:
• 1. Decay of tooth or neoplasm (abnormal new growth or tumor) in mouth or tongue due to
continuous irritation of nerve endings in the mouth.
• 2. Disease of esophagus, stomach and intestine.
• 3. Neurological disorders such as cerebral palsy, mental retardation, cerebral stroke and
parkinsonism.
• 4. Some psychological and psychiatric conditions.
• 5. Nausea and vomiting.

OTHER DISORDERS
• In addition to hyposalivation and hypersalivation, salivary secretion is affected by other
disorders also, which include:
• 1. Xerostomia
• 2. Drooling
• 3. Chorda tympani syndrome
• 4. Paralytic secretion of saliva
• 5. Augmented secretion of saliva
• 6. Mumps
• 7. Sjogren syndrome.

1. XEROSTOMIA
• Xerostomia means dry mouth. It is also called pasties or
cottonmouth.
• It is due to hyposalivation or absence of salivary secretion
(ptyalism).
• Causes
• Dehydration or renal failure.
• Sjogren syndrome.
• Radiotherapy.
• Trauma to salivary gland or their ducts.
• Side effect of some drugs like antihistamines, antidepressants,
monoamine oxidase inhibitors, antiparkinsonian drugs and
antimuscarinic drugs.
• Shock.
• After smoking marijuana (psychoactive com pound from the plant
Cannabis).
• Xerostomia causes difficulties in mastication, saw lowing and
speech. It also causes halitosis (bad breath; exhalation of

MIXED PAROTID TUMOR:
• It is slow-growing lobulated painless tumor of large superficial part of the parotid
gland.
• It is so called because of its mixed histological appearance, currently itis termed
pleomorphic adenoma.
• After many years of slow benign growth, it may undergo a malignant change

DROOLING
• Uncontrolled flow of saliva outside the mouth is called drooling.
• It is often called ptyalism.
• Causes Drooling occurs because of excess production of saliva, in association with inability to
retain saliva within the mouth.
• Drooling occurs in the following conditions:
• During teeth eruption in children.
• Upper respiratory tract infection or nasal allergies in children.
• Difficulty in swallowing.
• Tonsillitis.
• Peritonsillar abscess.

• Drooling is also caused by nervous system disorders that cause difficulty swallowing:4
• Cerebral palsy (CP)
• Parkinson's disease
• Amyotrophic lateral sclerosis (ALS)
• Down syndrome
• Multiple sclerosis
• Autism
• Stroke
• Other conditions that can cause the overproduction of saliva include:3
• epiglossitis (this is a rare but serious condition that causes swelling of the tongue).
• Sore throat
• Nasal obstruction
• Allergie
• Pregnancy (due to side effects)
• Swollen tongue or adenoids
• Muscular dystrophy
• Anaphylaxis (this is life-threatening and may be accompanied by other symptoms such as tongue swelling, difficulty breathing, hives, swelling of
the face).
• Use of certain medications

CHORDA TYMPANI SYNDROME
• Chorda tympani syndrome is the condition
characterized by sweating while eating.
During trauma or surgical
• Procedure, some of the parasympathetic
nerve fibers to salivary glands may be
severed.
• During the regeneration, some of these
nerve fibers, which run along with chorda
tympani branch of facial nerve may deviate
and join with the nerve fibers supplying
sweat glands.
• When the food is placed in the mouth,
salivary secretion is associated with sweat

PARALYTIC SECRETION OF SALIVA
• When the parasympathetic nerve to salivary gland is cut in experimental animals, salivary secretion
increases for first three weeks and later diminishes;
• finally, it stops at about sixth week.
• The increased secretion of saliva after cutting the parasympathetic nerve fibers is called paralytic
secretion.
• It is because of hyperactivity of sympathetic nerve fibers to salivary glands after cutting the
parasympathetic fibers.
• These hyperactive sympathetic fibers release large amount of catecholamines, which induce
paralytic secretion.
• Moreover, the acinar cells of the salivary glands become hypersensitive to catecholamines after
denervation.
• The paralytic secretion does not occur after the sympathetic nerve fibers to salivary glands are cut.

AUGMENTED SECRETION OF SALIVA
• If the nerves supplying salivary glands are stimulated twice,
• the amount of saliva secreted by the second stimulus is more than the amount
secreted by the first stimulus.
• It is because, the first stimulus increases excitability of acinar cells,
• so that when the second stimulus is applied,
• the salivary secretion is augmented.

MUMPS
• Mumps is the acute viral infection affecting the parotid glands.
• The virus causing this disease is paramyxovirus.
• It is common in children who are not immunized.
• It occurs in adults also.
• Features of mumps are puffiness of cheeks (due to swelling of parotid glands),
fever, sore throat and weakness.
• Mumps affects meninges, gonads and pancreas also.

SJOGREN SYNDROME
• Sjogren syndrome is an autoimmune disorder in which the immune cells destroy
exocrine glands such as lacrimal glands and salivary glands.
• It is named after Henrik Sjogren who discovered it.
• Common symptoms of this syndrome are dryness of the mouth due to lack of saliva
(xerostomia),
• persistent cough and dryness of eyes.
• In some cases, it causes dryness of skin, nose and vagina.
• In severe conditions, the organs like kidneys, lungs, liver, pancreas, thyroid, blood
vessels and brain are affected.

HARD AND SOFT PALATES DISSECTION
• Cut through the center of the
frontal bone, internasal suture,
intermaxillary sutures, chin,
hyoid bone, thyroid, cricoid and
tracheal cartilages; carry the
incision through the septum of
nose, nasopharynx, tongue,
and both the palates.
• Cut through the center of the
remaining occipital bone and
cervical vertebrae. This will
complete the sagittal section of
head and neck.

HARD PALATE AND HARD PALATE:
• Hard palate:
• Strip the mucoperiosteal of hard palate.
• Soft palate:
• Remove the mucous membrane of the soft palate in order to identify its muscles.
• Also remove the mucous membrane over palatoglossal and palatopharyngeal arches and
salpingopharyngeal fold to visualise the subjacent muscles.

HARD PALATE
• It is a partition between the nasal and oral cavities. Its anterior two – thirds are formed by the palatine
processes of the maxillae;
• and its posterior one – third by the horizontal plates of the palatine bones.
• The anterolateral margins of the palate are continuous with the alveolar arches and gums.
• The posterior margin gives attachment to the soft palate.
• The superior surface forms the floor of the nose.
• The inferior surface forms the roof of the oral cavity.
• Vessels and Nerves
• Arteries:
• Greater palatine branch of maxillary artery.
• Veins:
• Drain into the pterygoid plexus of veins.
• Nerves:
• Greater palatine and nasopalatine branches of the pterygopalatine ganglion suspended by the maxillary
nerve.
• Lymphatics:

SOFT PALATE
• It is a movable, muscular fold, suspended from the posterior border of the hard palate.
• It separates the nasopharynx from the oropharynx, and is often looked upon as traffic controller at the crossroads
between the food and air passages.
• The soft palate has two surfaces, anterior and posterior; and two borders, superior and inferior.
• The anterior (oral) surface is concave and is marked by a median raphe.
• The posterior surface is convex, and is continuous superiorly with the floor of the nasal cavity. The superior border is
attached to the posterior border of the hard palate, blending on each side with the pharynx.
• The inferior border is free and bounds the pharyngeal isthmus.
• From its middle, there hangs a conical projection, called the uvula.
• From each side of the base of the uvula (Latin small grape) two curved folds of mucous membrane extend laterally and
down wards.
• The anterior fold is called the palatoglossal arch or anterior pillar of faces. It contains the palatoglossus muscle and
reaches the side of the tongue at the junction of its oral and pharyngeal parts.
• This fold forms the lateral boundary of the oropharyngeal isthmus or isthmus of faces.
• The posterior fold is called the palatopharyngeal arch or posterior pillar of faces.
• It contains the palatopharyngeal muscle.
• It forms the posterior boundary of the tonsillar fossa, and merges inferiorly with the lateral wall of the pharynx.

STRUCTURE
• Soft palate comprises epithelium, connective
tissue and muscles.
• Epithelium is from the ectoderm of maxillary
process.
• The muscles are derived from 1st, 4th and 6th
branchial arches and accordingly are innervated
by mandibular and vagoaccessory complex.

STRUCTURE OF THE SOFT PLATE
• The soft palate is a fold of mucous membrane
containing the following parts:
• The palatine aponeurosis which is the flattened tendon
of the tensor veil palatini forms the fibrous basis of the
palate.
• Near the median plane, the aponeurosis splits to
enclose the musculus uvulae.
• The elevator veil palatini and the palatopharyngeal lie
on the superior surface of the palatine aponeurosis.
• The palatoglossus lies on the inferior or anterior
surface of the palatine aponeurosis.
• Numerous mucous glands, and some taste buds are
present.

MUSCLES OF THE SOFT PALATE
• They are as follows:
• 1 Tensor palate (tensor veil palatini).
• 2 levator palati (elevator veil palatini).
• 3 Musculus uvulae.
• 4 Palatoglossus.
• 5 Palatopharyngeal

NERVE SUPPLY
• 1 Motor nerves.
• All muscles of the soft palate except the tensor veil palatini are supplied by the pharyngeal plexus.
• The fibres of this plexus are derived from the cranial part of the accessory nerve through the vagus.
• The tensor veil palatini is supplied by the mandibular nerve.
• 2 General sensory nerves are derived from:
• a. The middle and posterior lesser palatine nerves, which are branches of the maxillary nerve through the
pterygopalatine ganglion.
• b. The glossopharyngeal nerve.
• 3 Special sensory or gustatory nerves
• carrying taste sensations from the oral surface are contained in the lesser palatine nerves.
• The fibres travel through the greater petrosal nerve to the geniculate ganglion of the facial nerve and from
there to the nucleus of the tracts solitarius.
• 4 Secretomotor nerves
• are also contained in the lesser palatine nerves.
• They are derived from the superior salivatory nucleus and travel through the greater petrosal nerve.

MOVEMENTS AND FUNCTIONS OF THE SOFT PALATE
• The palate controls two gates, upper air way or the pharyngeal isthmus and the upper food way on
oropharyngeal isthmus.
• The upper air way crosses the upper food way.
• The soft palate can compel tell close them, or can regulate their size according to requirements.
• Through these movements, the soft palate plays an important role in chewing, swallowing speech, coughing,
sneezing, etc.
• A few specific roles are given below.
• It isolates the mouth from the oropharynx during chewing, so that breathing is unaffected the hard palate.
• The unossified posterior part of fused palatal processes forms the soft palate.
• 2 It separates the oropharynx from the nasopharynx by locking Passavant’s ridge during the second stage of
swallowing, so that food does not enter the nose.
• 3 By varying the degree of closure of the pharyngeal isthmus, the quality of voice can be modified and various
consonants are correctly pronounced.
• 4 During sneezing, the blast of air is appropriately divided and directed through the nasal and oral cavities
without damaging the narrow nose.
• Similarly, during coughing, it directs air and sputum into the mouth and not into the nose.

BLOOD SUPPLY
• Arteries
• 1 Greater palatine branch of maxillary artery.
• 2 Ascending palatine branches of facial artery.
• 3 Palatine branches of ascending pharyngeal artery.
• Veins
• They pass to the pterygoid and tonsillar plexuses of veins.
• Lymphatics
• Drain into the upper deep cervical and retropharyngeal lymph nodes

DEVELOPMENT OF PALATE
• The premaxilla or primitive palate carrying upper four incisor teeth is formed by the fusion
of medial nasal folds, which are folds not frontonasal process.
• The rest of the palate is formed by the shelf like palatine processes of maxilla and horizontal
plates of palatine bone.
• Most of the palate gets ossified to form the hard palate.
• The unossified posterior part of fused palatal processes forms the soft palate

CLINICAL ANATOMY
• Cleft palate
• is a congenital defect caused by non-fusion of the right and left palatal processes.
• It may be of different degrees. In the least severe type, the defect is confined to the soft
palate.
• In the most severe cases, the cleft in the palate is continuous with harelip.
• • Paralysis of the soft palate in lesions of the vagus nerve produces:
• a. Nasal regurgitation of liquids
• b. Nasal twang in voice
• c. Flattening of the palatal arch
• d. Deviation of uvula to normal side.

TONGUE
• INTRODUCTION
• The tongue is a muscular organ situated in the floor of the mouth.
• It is associated with the functions of
• taste,
• speech,
• chewing, and
• deglutition.
• Tongue comprises skeletal muscle which is voluntary.
• These voluntary muscles start behaving as involuntary in any classroom – funny? Thanks to the
taste buds that the multiple hotels, restaurants, fast food outlets, chat – parishes, etc. are
flourishing.
• One need not be too fussy about the taste of the food. Nutritionally, it should be balanced and
hygienic.

EXTERNAL FEATURES DISSECTION
• In the sagittal section, identify fan –
shaped genioglossus muscle.
• Cut the attachments of buccinator,
superior constrictor muscles and the
intervening pterygoid mandibular raphe
and reflect these downwards exposing
the lateral surface of the tongue.
• Look at the superior, inferior surfaces of
your own tongue with the help of hand
lens.

PARTS
• The tongue has:
• 1 A root,
• 2 A tip, and
• 3 A body,
• which has:
• a. A curved upper surface or dorsum
• b. An inferior surface.

• The dorsum is divided into oral and pharyngeal parts by a V – shaped, the sulcus
terminalis.
• The inferior surface is confined to the oral part only.
• The root is attached to the styloid process and soft palate above, and to mandible and the
hyoid bone Below.
• Because of these attachments, we are not able to swallow the tongue itself.
• In between the mandible and hyoid bones, it is related to the geniohyoid and mylohyoid
muscles.
• The tip of the tongue forms the anterior free end which, at rest, lies behind the upper
incisor teeth.
• The dorsum of the tongue is convex in all directions

IT IS DIVIDED INTO:
• ` • An oral part or anterior two – thirds.
• A pharyngeal part or posterior one – third, by a faint V – shaped groove, the sulcus
terminalis.
• The two limbs of the ‘V ‘meet at a median pit, named the foramen caecum.
• They run laterally and forwards up to the palatoglossal arches.
• The foramen caecum represents the site from which the thyroid diverticulum grows
down in the embryo.
• The oral and pharyngeal parts of the tongue differ in their development, topography,
structure, and function.

• SMALL POSTERIOR MOST PART
• The oral or papillary part of the tongue is placed on the floor of the mouth.
• Its margins are free and in contact with the gums and teeth.
• Just in front of the palati glossal arch, each margin shows 4 to 5 vertical folds, named the foliate
papillae.
• The superior surface of the oral part shows a median furrow and is covered with papillae which make it
rough.
• The inferior surface is covered with a smooth mucous membrane, which shows a median fold called
the frenulum linguae.
• On either side of the frenulum, there is a prominence produced by the deep lingual veins.
• More laterally there is a fold called the plica fimbriata that is directed Forwards and medially towards
the tip of the tongue.

2 THE PHARYNGEAL OR LYMPHOID PART OF THE TONGUE
• lies behind the palatoglossal arches and the sulcus terminalis.
• Its posterior surface, sometimes called the base of the tongue, forms the anterior wall of the
oropharynx.
• The mucous membrane has no papillae, but has many lymphoid follicles that collectively constitute
the lingual tonsil.
• Mucous glands are also present.
• 3 The posterior most part of the tongue is connected to the epiglottis by three – folds of mucous
membrane.
• These are the median gloss epiglottic fold and the right and left lateral gloss epiglottic folds.
• On either side of the median fold, there is a depression called the vallecula.
• The lateral folds separate the vallecula from the piriform fossa.

PAPILLAE OF THE TONGUE
• These are projections of mucous
membrane or corium which give the
anterior two – thirds of the tongue its
characteristic roughness.
• 1 Vallate or circumvallate papillae
• 2 The fungiform papillae
• 3 The filiform papillae or conical papillae
• 4 Few foliate papillae are also present.

1 VALLATE OR CIRCUMVALLATE PAPILLAE:
• Circumvallate papillae are large structures present on the posterior part of tongue and
are many in number.
• These papillae are arranged in the shape of ‘V ‘. Each papilla contains many taste buds
(up to 100).
• They are large in size 1-2 mm in diameter and are 8-12 in number.
• They are situated immediately in front of the sulcus terminalis.
• Each papilla is a cylindrical projection surrounded by a circular sulcus.
• The walls of the papilla have taste buds.

2 THE FUNGIFORM PAPILLAE
• Fungiform papillae are round in shape and are situated over the anterior surface of tongue
near the tip.
• Numerous fungiform papillae are present.
• Each papilla contains moderate number of taste buds (up to 10).
• are numerous near the tip and margins of the tongue, but some of them are also Scattered
over the dorsum.
• These are smaller than the vallate papillae but larger than the filiform papillae.
• Each papilla consists of a narrow pedicle and a large rounded head.
• They are distinguished by their bright red colour.

THE FILIFORM PAPILLAE OR CONICAL PAPILLAE
• Filiform papillae are small and conical – shaped papillae, situated over the dorsum of tongue.
• These papillae contain a smaller number of taste buds (only a few).
• cover the presacral area of the dorsum of the tongue, and give it a characteristic velvety
appearance.
• They are the smallest and most numerous of the lingual papillae.
• Each is pointed and covered with keratin;
• the apex is often split into filamentous processes.

DEVELOPMENT OF TONGUE
• 1 Anterior two – thirds:
• From two lingual swellings, which arise from the first branchial arch (Fig. 17.11). Therefore, it is
supplied by lingual nerve (post thematic) of 1st arch and chorda tympani (pre-thematic) of 2nd
arch. 2nd arch 4th arch 1st arch 3rd arch 3rd arch 1st arch 4th arch 2nd arch:
• 2 Posterior one – third:
• From cranial large part of the hypobranchial eminence, i.e. from the third arch. Therefore, it is
supplied by the glossopharyngeal nerve.
• 3 Posterior most part from the fourth arch.
• This is supplied by the vagus nerve.
• Muscles
• The muscles develop from the occipital myotomes which are supplied by the hypoglossal nerve.
Connective Tissue The connective tissue develops from the local mesenchyme.

MUSCLES OF THE TONGUE
• A middle fibrous septum divided the
tongue into right and left halves. Each half
contains four intrinsic and four extrinsic
muscles.
• Intrinsic Muscles
• Extrinsic Muscles

INTRINSIC MUSCLES
• Intrinsic Muscles
• 1 Superior longitudinal
• 2 Inferior longitudinal
• 3 Transverse
• 4 Vertical.
• The intrinsic muscles
• occupy the upper part of the tongue, and are attached to the submucous fibrous layer and to the median fibrous septum.
• They alter the shape of the tongue. The superior longitudinal muscle lies beneath the mucous membrane.
• The inferior longitudinal muscle is a narrow band lying close to the inferior surface of the tongue between the genioglossus
and the hyoglossus.
• The transverse muscle extends from the median septum to the margins.
• The vertical muscle is found at the borders of the anterior part of the tongue.

EXTRINSIC MUSCLES
• 1 Genioglossus
• 2 Hyoglossus
• 3 Styloglossus
• 4 Palatoglossus the extrinsic muscles
• connect the tongue to the mandible via
genioglossus;
• to the hyoid bone through hyoglossus;
• to the styloid process via styloglossus, and the
palate via palatoglossus.

ARTERIAL SUPPLY OF TONGUE
• Arterial Supply of Tongue
• It is derived from the tortuous lingual artery a branch
of the external carotid artery.
• The root of the tongue is also supplied by the tonsillar
artery a branch of facial artery, and ascending
pharyngeal branch of external carotid.
• branches of the lingual artery.
• Venous Drainage
• The arrangement of the vena comitantes veins of the
tongue is variable.
• These veins unite at the posterior border of the
hyoglossus to form the lingual vein which ends in the
internal jugular vein.

LYMPHATIC DRAINAGE
• 1 The tip of the tongue drains bilaterally to the
submental nodes.
• 2 The right and left halves of the remaining part of the
anterior two – thirds of the tongue drain unilaterally to
the submandibular nodes.
• A few central lymphatics drain bilaterally to the deep
cervical nodes.
• 3 The posterior most part and posterior one third of the
tongue drain bilaterally into the upper deep cervical
lymph nodes including jugulodigastric nodes.
• 4 The whole lymph finally drains to the jugular –
omohyoid nodes. These are known as the lymph nodes
of the tongue.

NERVE SUPPLY
• Motor Nerves
• All the intrinsic and extrinsic muscles, except the palatoglossus, are supplied by the
hypoglossal nerve.
• The palatoglossus is supplied by the cranial root of the accessory nerve through the
pharyngeal plexus.
• So, seven out of eight muscles are supplied by XII nerve.
• Sensory Nerves
• The lingual nerve is the nerve of general sensation and the chorda tympani is the nerve of
taste for the anterior two – thirds of the tongue except vallate papillae.
• The glossopharyngeal nerve is the nerve for both general sensation and taste for the posterior
one – third of the tongue including the circumvallate papillae.

TASTE BUDS
• Sense organs for taste or gustatory sensation are the taste buds.
• Taste buds are ovoid bodies with a diameter of 50 μ to 70 μ.
• In adults, about 10,000 taste buds are present and the number is more in
children.
• In old age, many taste buds degenerate and the taste sensitivity
decreases.
• ■ SITUATION OF TASTE BUDS
• Most of the taste buds are present on the papillae of tongue.
• Taste buds are also situated in the mucosa of epiglottis, palate, pharynx
and the proximal part of esophagus.
• PATHWAY FOR TASTE RECEPTORS
• for taste sensation are the type III cells of taste buds.
• Each taste bud is innervated by about 50 sensory nerve fibers and each
nerve fiber supplies at least five taste buds through its terminals.

■ STRUCTURE OF TASTE BUD
• Taste bud is a bundle of taste receptor cells, with supporting cells embedded in the epithelial covering of the papillae.
• Each taste bud contains about 40 cells, which are the modified epithelial cells.
• Cells of taste bud are divided into four groups:
• Type of Cells in Taste Bud
• 1. Type I cells or sustentacular cells
• 2. Type II cells
• 3. Type III cells
• 4. Type IV cells or basal cells.
• Type I cells and type IV cells are supporting cells.
• Type III cells are the taste receptor cells.
• Function of type II cell is unknown.
• Type I, II and III cells have microvilli, which project into an opening in epithelium covering the tongue.
• This opening is called taste pore.
• Neck of each cell is attached to the neck of other.
• All the cells of taste bud are surrounded by epithelial cells.
• There are tight junctions between epithelial cells and the neck portion of the type I, II and III cells, so that only the tip of these cells are
exposed to fluid in oral cavity.
• Cells of taste buds undergo constant cycle of growth, apoptosis and regeneration.

FIRST ORDER NEURON
• First order neurons of taste pathway are in the nuclei of three different cranial nerves,
situated in medulla oblongata.
• Dendrites of the neurons are distributed to the taste buds.
• After arising from taste buds, the fibers reach the cranial nerve nuclei by running along the
following nerves:
• 1. Chorda tympani fibers of facial nerve, which run from anterior two third of tongue
• 2. Glossopharyngeal nerve fibers, which run from posterior one third of the tongue
• 3. Vagal fibers, which run from taste buds in other regions.
• Axons from first order neurons in the nuclei of these nerves run together in medulla
oblongata and terminate in the nucleus of tracts solitarius.

• ■ SECOND ORDER NEURON
• Second order neurons are in the nucleus of tracts solitarius.
• Axons of second order neurons run through medial lemniscus and terminate in
posteroventral nucleus of thalamus.
• THIRD ORDER NEURON
• Third order neurons are in the posteroventral nucleus of thalamus.
• Axons from third order neurons project into parietal lobe of the cerebral cortex.

TASTE CENTER
• Center for taste sensation is in opercular insular cortex, i.e. in
the lower part of postcentral gyrus, which receives cutaneous
sensations from face.
• Thus, the taste fibers do not have an independent cortical
projection.
• ■ PRIMARY TASTE SENSATIONS
• Primary or fundamental taste sensations are divided into five
types:
• 1. Sweet
• 2. Salt
• 3. Sour
• 4. Bitter
• 5. Umami.
• Man can perceive more than 100 different tastes.

DISCRIMINATION OF DIFFERENT TASTE SENSATIONS
• Earlier, it was believed that different areas of tongue were specialized for different taste
sensation.
• Now it is clear that all areas of tongue give response to all types of taste sensations.
• Usually, in low Concentra ton of taste substance, each taste bud gives response to one
primary taste stimulus.
• However, in high concentration, the taste buds give response to more than one type of taste
stimuli.
• It is also clear now that each afferent nerve fiber from the taste buds carry impulses of one
taste sensation.

TASTE SENSATIONS AND CHEMICAL CONSTITUTIONS
• Substances causing sour or salt tastes are mostly electrolytes. Bitter and sweet
tastes are caused by electrolytes or non – electrolytes.
• SWEET TASTE
• SALT TASTE
• SOUR TASTE
• BITTER TASTE
• UMAMI

• ■ SWEET TASTE
• Sweet taste is produced mainly by organic substances like monosaccharides,
polysaccharides, glycerol, alcohol, aldehydes, ketones and chloroform.
• Inorganic substances, which produce sweet taste are led and beryllium.
• SALT TASTE
• Salt taste is produced by chlorides of sodium, potassium and ammonium, nitrates of
sodium and potassium.
• Some sulfates, bromides and iodides also produce salt taste.
• SOUR TASTE
• Sour taste is produced because of hydrogen ions in acids and acid salts.

BITTER TASTE AND UMAMI
• BITTER TASTE
• Bitter taste is produced by organic substances like quinine, strychnine, morphine, glucosides, picric
acid and bile salts and inorganic substances like salts of calcium, magnesium and ammonium.
• Bitterness of the salts is mainly due to cations.
• UMAMI
• Umami is the recently recognized taste sensation.
• Umami is a Japanese word, meaning ‘delicious ‘.
• Receptors of this taste sensation respond to glutamate, particularly monosodium glutamate
(MSG), which is a common ingredient in Asian food.
• However, excess MSG consumption is proved to produce

THRESHOLD FOR TASTE SENSATIONS
• Sweet Taste Sugar:
• 1 in 200 dilution
• Salt taste Sodium chloride
• 1 in 400 dilution
• Sour taste Hydrochloric acid:
• 1 in 15,000 dilution
• Bitter taste Quinine:
• 1 in 2,000,000 dilution.
• Bitter taste has very low threshold and
• sweet taste has a high threshold.
• Threshold for umami is not known.

• SWEET RECEPTOR
• Receptor for sweet taste is GPCR. The sweet substances bind to receptor and cause
depolarization via cyclic AMP.
• SALT RECEPTOR
• Receptor for salt taste is called epithelial sodium channel (ENaC).
• It acts like ENaC receptors in other parts of the body.
• When sodium enters, this receptor releases glutamate, which causes depolarization.
• SOUR RECEPTOR
• Sour sensation also has the same ENaC receptor.
• The proton (hydrogen) enters the receptor and causes depolarization.
• It is believed that besides ENaC, other receptors such as hyperpolarization – activated cyclic
nucleotide – gated cation channel (HCN) also are involved in sour sensation.

• BITTER RECEPTOR
• Bitter receptor is a GPCR.
• In bitter receptor, the sour substances activate phospholipase C through G proteins.
• It causes production of inositol triphosphate (IP), which initiates depolarization by releasing
calcium ions.
• ■ UMAMI RECEPTOR
• Umami receptor is called metabotropic glutamate receptor (mGluR4).
• Glutamate causes depolarization of this receptor.
• Exact mechanism of depolarization is not clearly understood.
• Activation of umami taste receptor Is intensified by the presence of guanosine mono
phosphate (GMP) and inosine monophosphate (IMP).

APPLIED PHYSIOLOGY –
ABNORMALITIES OF TASTE SENSATION AGEUSIA
• Loss of taste sensation is called ageusia.
• Taste buds in anterior two thirds of the tongue are innervated by the chorda tympani branch
of facial nerve.
• Chorda tympani nerve receives taste fibers from tongue via lingual branch of mandibular
division of trigeminal nerve.
• So, the lesion in facial nerve, chorda tympani or mandibular division of trigeminal nerve
causes loss of taste sensation in the anterior two third of the tongue.
• Lesion in glossopharyngeal nerve leads to loss of taste in the posterior one third of the
tongue.
• Temporary loss of taste sensation occurs due to the drugs like captopril and penicillamine,
which contain sulfhydryl group of substances.

HYPOGEUSIA
• Hypogeusia is the decrease in taste sensation.
• It is due to increase in threshold for different taste sensations.
• However, the taste sensation is not completely lost.

• TASTE BLINDNESS
• Taste blindness is a rare genetic disorder in which the ability to recognize substances by
taste is lost.
• DYSGEUSIA
• Disturbance in the taste sensation is called dysgeusia.
• It is found in temporal lobe syndrome, particularly when the anterior region of temporal
lobe is affected.
• In this condition, the paroxysmal hallucinations of taste and smell occur, which are usually
unpleasant.

CLINICAL ANATOMY
• Injury
to any part of the pathway causes abnormality in appreciation of taste.
Referred pain
• is felt in the ear in diseases of posterior part of the tongue, as ninth and tenth
nerves are common supply to both the regions.
•

• CARCINOMA OF THE TONGUE
• is quite common.
• The affected side of the tongue is removed surgically.
• All the deep cervical lymph nodes are also removed,
• i.e. block dissection of neck because
• Recurrence of malignant disease occurs in lymph nodes.
• Carcinoma of the posterior one – third of the tongue is more dangerous due to bilaterally
ephatic spread.

SAFETY MUSCLE OF THE TONGUE
• • Genioglossus is called the ‘safety muscle of the tongue ‘because if it is paralyzed, the tongue will fall
back on the oropharynx and block the air passage.
• During anesthesia, the tongue is pulled forwards to clear the air passage.
• ● Genioglossus is the only muscle of the tongue which protrudes it forwards.
• It is used for testing the integrity of hypoglossal nerve.
• If hypoglossal nerve of right side is paralyzed, the tongue on protrusion will deviate to the right side.
• Normal left genioglossus will pull the base to left side and apex will get pushed to right side (apex and
base lie at opposite ends).

TONSIL
• Palatine tonsil is almond – shaped.
• This surface has 12 to 15 crypts.
• The largest of these is called the intertonsillar cleft.
• The palatine tonsil (Latin swelling) occupies the tonsillar sinus or fossa between the palatoglossal and
palatopharyngeal arches.
• It can be seen through the mouth.
• It has two surfaces
• medial and
• lateral;
• two borders,
• anterior and
• posterior and
• two poles,
• upper and lower.

• The tonsillar artery enters the tonsil by piercing the superior constrictor just
behind the firm attachment.
• The palatine vein may be injured during removal of the tonsil or tonsillectomy.
• This firm attachment keeps the tonsil in place during swallowing.

TONSILLAR BED
• The bed of the tonsil is formed from within outwards by:
• a. The pharyngobasilar fascia.
• b. The superior constrictor and palatopharyngeus muscles.
• c. The buccopharyngeal fascia.
• d. In the lower part, the styloglossus.
• e. The glossopharyngeal nerve.

• Arterial Supply of Tonsil
• 1 Main source: Tonsillar branch of facial artery.
• 2.Additional sources
• a. Ascending palatine branch of facial artery.
• b. Dorsal lingual branches of the lingual artery.
• c. Ascending pharyngeal branch of the external carotid artery.
• d. The greater palatine branch of the maxillary artery.
• Venous Drainage
• One or more veins leave the lower part of deep surface of the tonsil, pierce the superior constrictor,
and join the palatine, pharyngeal, or facial veins.
• Lymphatic Drainage
• Lymphatics pass to jugulodigastric node.
• There are no afferent lymphatics to the tonsil.
• Nerve Supply
• Glossopharyngeal and lesser palatine nerves.

CLINICAL ANATOMY
• The tonsils are large in children.
They retrogress after puberty.
• The tonsils are frequently sites of infection, especially in children. Infection may spread to surrounding tissue forming a
peritonsillar abscess.
Enlarged and infected tonsils often require surgical removal.
The operation is called tonsillectomy.
A knowledge of the relationship of the tonsil is of importance to the surgeon.
• Tonsillectomy
is usually done by the guillotine method.

Haemorrhage after tonsillectomy
is checked by removal of clot from the raw tonsillar bed.
This is to be compared with the method for checking postpartum haemorrhage from the uterus.
These are the only two organs in the body where bleeding is checked by removal of clots.
In Other parts of the body, clot formation is encouraged.
• Tonsillitis may cause referred pain
in the ear as glossopharyngeal nerve supplies both these areas.
Suppuration in the peritonsillar area is called quinsy.
A peritonsillar abscess is drained by making an incision in the most prominent point of the abscess.
• Tonsils are often sites of a septic focus.
Such a focus can lead to serious disease like pulmonary tuberculosis, meningitis, etc. and is often the cause of general ill health.

PHARYNX
• DISSECTION
• Identify the structures in the interior of three parts of
pharynx, i.e. nasopharynx,
• oropharynx and laryngopharynx.
• Clean the surfaces of buccinator muscle and adjoining
superior constrictor muscles by removing connective
tissue and buccopharyngeal fascia over these
muscles.
• Detach the medial pterygoid muscle from its origin
and reflect it downwards.
• This will expose the superior constrictor muscle
completely.

INTRODUCTION
• The pharynx (Latin throat) is a wide
muscular tube, situated behind the nose,
the mouth and the larynx.
• Clinically, it is a part of the upper
respiratory passages where infections are
common.
• The upper part of the pharynx transmits
only air, the lower part (below the inlet of
the larynx), only food, but the middle part
is a common passage for both air and
food.

DIMENSIONS OF PHARYNX LENGTH:
• Width --About 12 cm
• 1 Upper part is widest (3.5 cm) and no collapsible
• 2 Middle part is narrow
• 3 The lower end is the narrowest part of the gastro intestinal tract (except for the appendix).
• Boundaries
• Superiorly
• Base of the skull, including the posterior part of the body of the sphenoid and the basilar part of the occipital bone, in front
of the pharyngeal tubercle.
• Inferiorly
• The pharynx is continuous with the esophagus at the level of the sixth cervical vertebra, corresponding to the lower border
of the cricoid cartilage.
• Posteriorly
• The pharynx glides freely on the prevertebral fascia which separates it from the cervical vertebral bodies.
• Anteriorly
• It communicates with the nasal cavity, the oral cavity and the larynx.
• Thus, the anterior wall of the pharynx is incomplete.

PARTS OF THE PHARYNX
• The cavity of the pharynx is
divided into:
• 1 The nasal part,
nasopharynx
• 2 The oral part, oropharynx
• 3 The laryngeal part,
laryngopharynx.
• Comparison between
nasopharynx, oropharynx
and laryngopharynx

• The wall of the pharynx is composed of the following five layers from within outwards.
• 1 Mucosa
• 2 Submucosa
• 3 Pharyngobasilar fascia or pharyngeal aponeurosis.
• This is a fibrous sheet internal to the pharyngeal muscles.
• It is thickest in the upper part where it fills gap between the upper border of the superior
constrictor and the base of the skull, and also posteriorly where it forms pharyngeal
raphe.
STRUCTURE OF PHARYNX

ORIGIN OF CONSTRICTORS
• 1 The superior constrictor takes origin
• from the following (from above downwards):
• a. Pterygoid hamulus (pterygopharyngeus).
• b. Pterygomandibular raphe (buccopharyngeus).
• c. Medial surface of the mandible at the posterior end of the mylohyoid line, i.e. near the lower
attachment of the pterygomandibular raphe (mylopharyngeus).
• d. Side of posterior part of tongue (glossopharyngeus).
• 2 The middle constrictor takes origin from:
• a. The lower part of the stylohyoid ligament
• b. Lesser cornu of hyoid bone
• c. Upper border of the greater cornu of the hyoid bone.
• 3 The Inferior constrictor consists of two parts.

INSERTION OF CONSTRICTORS
• All the constrictors of the pharynx are inserted into a median raphe on the posterior wall of the
pharynx.
• The upper end of the raphe reaches the base of the skull where it is attached to the pharyngeal
tubercle on the basilar part of the occipital bone.
• Longitudinal Muscle Coat the pharynx has three muscles that run longitudinally.
• The stylopharyngeus arises from the styloid process.
• It passes through the gap between the superior and middle constrictors to run downwards on
the inner surface of the middle and inferior constrictors.
• The fibres of the palatopharyngeus descend from the sides of the palate and run longitudinally
on the inner aspect of the constrictors.

• Blood Supply
• The arteries supplying the pharynx are as follows.
• 1 Ascending pharyngeal branch of the external carotid artery.
• 2 Ascending palatine and tonsillar branches of the facial artery.
• 3 Dorsal lingual branches of the lingual artery.
• 4 The greater palatine, pharyngeal and pterygoid branches of the maxillary artery.
• VENOUS DRAINAGE
• The veins form a plexus on the posterolateral aspect of the pharynx.
• The plexus receives blood from the pharynx, the soft palate and the prevertebral region.
• It drains into the internal jugular and facial veins.
• Lymphatic Drainage
• Lymph from the pharynx drains into the retro pharyngeal and deep cervical lymph nodes.

CLINICAL ANATOMY
• Difficulty in swallowing is known as dysphagia.
• Pharyngeal diverticulum: Read Killian’s dehiscence

DEGLUTITION (SWALLOWING) SWALLOWING OF FOOD
• occurs in three stages described below.
• First Stage
• 1 This stage is voluntary in character.
• 2 The anterior part of the tongue is raised and pressed against the hard palate by the intrinsic
muscles of the tongue, especially the superior longitudinal and transverse muscles.
• The movement takes place from anterior to the posterior side.
• This pushes the food bolus (Greek lump) into the posterior part of the oral cavity.
• 3 The soft palate closes down on to the back of the tongue, and helps to form the bolus.
• 4 Next, the hyoid bone is moved upwards and forwards by the suprahyoid muscles.
• The posterior part of the tongue is elevated upwards and backwards by the styloglossi; and
the palatoglossal arches are approximated by the palatoglossal.
• This pushes the bolus through the oropharyngeal isthmus to the oropharynx, and the second
stage begins.

Second Stage
• 1 It is involuntary in character. During this stage, the food is pushed from the oropharynx to the lower part of the laryngopharynx.
• Posterior pharyngeal wall (ridge of Passavant).
• This prevents the food bolus from entering the nose.
• 3 The inlet of larynx is closed by approximation of the aryepiglottic folds by aryepiglottic and oblique arytenoid.
• This prevents the food bolus from entering the larynx.
• 4 Next, the larynx and pharynx are elevated behind the hyoid bone by the longitudinal muscles of the pharynx, and the bolus is pushed down over the posterior
surface of the epiglottis, the closed inlet of the larynx and the posterior surface of the arytenoid cartilages, by gravity, and by contraction of the superior and middle
constrictors and of the palatopharyngeus.
Third Stage
• 1 This is also involuntary in character. In this stage, food passes from the lower part of the pharynx to the oesophagus.
• 2 This is brought about by the inferior constrictors of the pharynx.

OESOPHAGUS
• The oesophagus is a narrow muscular tube extending from pharynx to the stomach.
• It is about 25 cm long and provides passage for chewed food (bolus) and liquids during the
third stage of deglutition.
• The anatomy of oesophagus is clinically important because of its involvement in various
diseases such as esophagitis, oesophageal varices and cancer.
• It begins with lower part of the neck and terminates in the upper part of the abdomen by
joining the upper end of stomach.

• DIMENSIONS AND LUMEN
• Length: 25 cm (10 inches).
• Width: 2 cm.
• Lumen:
• It is flattened anteroposteriorly.
• Normally it is kept closed (collapsed) and opens (dilates) only during the passage of the
food.
• COURES
• The oesophagus begins in the neck at the lower border of the cricoid cartilage (at the lower
border of C6 vertebra),
• descends in front of the vertebral column passes through superior and posterior mediastina,
pierces diaphragm at the level of T10 vertebra and
• ends in the abdomen at the cardiac orifice of the stomach at the level of T11vertebra.

CONSTRICTIONS
• Normally, there are four sites of anatomical constrictions/ narrowing in the oesophagus.
• The distance of each constriction is measured from the upper incisor teeth.
• The constrictions are as follows:
• 1. First constriction, at the pharyngo-oesophageal junction, 9 cm (6 inches) from the incisor
teeth.
• 2. Second constriction, where it is crossed by the arch of aorta, 22.5 cm (9 inches) from the
incisor teeth.
• 3. Third constriction, where it is crossed by the left principal bronchus, 27.5 cm (11 inches)
from the incisor teeth.
• 4. Fourth constriction, where it pierces the diaphragm, 40 cm (15 inches) from the incisor
teeth,
• N.B. The narrowest part of oesophagus is its commencement at the cricopharyngeal sphincter.

PARTS OF THE ESOPHAGUS
• The oesophagus is divided into the following three
parts:
• 1. Cervical part (4 cm in length).
• 2. Thoracic part (20 cm in length).
• 3. Abdominal part (1-2 cm in length).
• The cervical part extends from the lower border of
cricoid cartilage to the superior border of
manubrium sterni.
• The thoracic part extends from superior border of
manubrium sterni to the oesophageal opening in
the diaphragm.
• The abdominal part extends form oesophageal
opening in the diaphragm to the cardiac end of the
stomach.

RELATIONS OF THORACIC PART OF THE ESOPHAGUS
Anterior: From above downwards these are
as follows:
• 1. Trachea.
• 2. Arch of aorta.
• 3. Right pulmonary artery.
• 4. Left principal bronchus.
• 5. Left atrium enclosed in the
pericardium.
• 6. Diaphragm.
• Posterior:
• 1. Vertebral column.
• 2. Right posterior intercostal arteries.
• 3.Thoracic duct.
• 4. Azygos vein.
• 5. Hemiazygos veins (terminal parts).
• 6. Descending thoracic aorta.
.

To the right:
• 1. Right lung and pleura.
• 2. Azygos vein.
• 3. Right vagus nerve.
To the left:
• 1. Arch of aorta.
• 2. Left subclavian artery.
• 3. Thoracic duct.
• 4. Left lung and pleura.
• 5. Left recurrent laryngeal nerve
• 6. Descending thoracic aorta.
• N.B. In the oesophageal aperture of the diaphragm, the left vagus nerve (now called anterior
gastric nerve) is related anteriorly and right vagus nerve (now called posterior gastric nerve)
is related posteriorly

RELATIONS OF ABDOMINAL PART OF THE ESOPHAGUS
• Anterior:
• 1. Posterior surface of the left lobe
of the liver.
• 2. Left gastric nerve.
• Posterior:
• 1. Left crus of diaphragm.
• 2. Right gastric nerve.
• N.B. The abdominal part of
oesophagus is shortest (1 to 2 cm
long) and is the only part covered
with serous membrane the
peritoneum.

• ARTERIAL SUPPLY
• • Blood supply to the cervical part is by inferior thyroid arteries.
• • Blood supply to the thoracic part is by oesophageal branches of
• (a) descending thoracic aorta, and
• (b) bronchial arteries.
• • Blood supply to the abdominal part is by oesophageal branches of
• (a) left gastric artery, and
• (b) left inferior phrenic artery.
• VENOUS DRAINAGE
• • Cervical part is drained by inferior thyroid veins.
• • Thoracic part is drained by azygos and hemiazygos veins.
• • Abdominal part is drained by two venous channels, viz.
• (a) hemiazygos vein, a tributary of inferior vena cava, and
• (b) left gastric vein, a tributary of portal vein.
• Thus, abdominal part of oesophagus is the site of portocaval anastomosis.

• LYMPHATIC DRAINAGE
• From cervical part, the lymph is drained into deep cervical lymph nodes.
• From thoracic part, the lymph is drained into posterior mediastinal lymph nodes.
• From abdominal part, the lymph is drained into left gastric lymph nodes.
• NERVE SUPPLY
• The oesophagus is supplied by both parasympathetic and sympathetic fibres.
• The parasympathetic fibres are derived from recurrent laryngeal nerves and oesophageal
plexuses formed by vagus nerves.
• They provide sensory, motor, and secretomotor supply to the oesophagus.
• The sympathetic fibres are derived from T5-T9 spinal Segments are sensory and vasomotor

CLINICAL CORRELATION
• • Radiological examination of the oesophagus by barium swallow:
• It is performed to detect
• (a) enlargement of the left atrium due to mitral stenosis,
• (b) oesophageal strictures, and
• (c) carcinoma and achalasia cardia.
• N.B. In normal case, the barium swallow examination presents 3 indentations in its outline
caused by the aortic arch, left principal bronchus, and left atrium.
• •The lower end of the oesophagus is prone for inflammation and ulceration due to acidic
regurgitation from the stomach,
• • The lower end of the oesophagus is the commonest site of carcinoma.

ESOPHAGOSCOPY
• It is performed to visualize the interior of the oesophagus; while passing esophagoscope, the
siles of normal constrictions should be kept in mind.

ACHALASIA CARDIA:
• It is a clinical condition in which sphincter at the lower end of oesophagus fails to relax when the
food is swallowed.
• As a result, food accumulates in the oesophagus and its regurgitation occurs.
• This condition occurs due to neuromuscular incoordination, probably due to congenital absence
of ganglion cells in the myenteric plexus of nerves in the oesophageal wall.
• A radiographic barium swallow examination of the oesophagus reveals a characteristic bird’s
beak/rat tail.
• Due to neuromuscular incoordination sometimes, the lower end of the oesophagus fails to open
and does not allow smooth passage of food leading to dysphagia called achalasia cardia.
• Marked dilatation of the oesophagus may occur due to accumulation of food within it.

• DYSPHAGIA (DIFFICULTY IN SWALLOWING):
• It occurs due to:
• (a) compression of oesophagus from outside by aortic arch aneurysm, enlargement of lymph
nodes, abnormal right subclavian artery (passing posterior to oesophagus), etc. and
• (b) narrowing of lumen due to stricture or carcinoma,

TRACHEOESOPHAGEAL FISTULA:
• It is a commonest congenital anomaly of oesophagus which occurs due b failure of separation
of the lumen of tracheal tube from that of oesophagus by a laryngotracheal septum.
• In the commonest type of tracheoesophageal fistula, the upper oesophagus ends blindly and
lower oesophagus communicates with trachea at the level of T4 vertebra, clinically it presents
as:
• (a) hydramnios because fetus is unable to swallow amniotic fluid,
• (b) stomach is distended with air, and
• (c) infant vomit every feed given or may cough up bile.
• The fistula must be closed surgically to avoid passage of swallowed liquids into the lungs.

• MALIGNANT TUMORS OF OESOPHAGUS:
• They most commonly the lymph vessels from lower one-third of the oesophagus
descend through the oesophageal opening of the diaphragm and drain into the
celiac lymph nodes around the celiac trunk.
• A malignant tumor from lower one-third of oesophagus, therefore, spreads below
the diaphragm into these lymph nodes.

OESOPHAGEAL VARICES:
• The lower end of the oesophagus is one of the important sites of portocaval
anastomosis.
• In portal hypertension (e.g., due to cirrhosis of the Liver), the portocaval
anastomotic channels open and become dilated and tortuous forming
oesophageal varices.
• Their rupture may cause severe and fatal hematemesis (vomiting of blood).

DIAPHRAGM
• The diaphragm is an unpaired, dome shaped skeletal muscle that is located in the trunk.
• It separates the thoracic and abdominal cavities from each other by closing the inferior
thoracic aperture.
• The diaphragm is the primary muscle that is active in inspiration.
• Contraction of the muscle facilitates expansion of the thoracic cavity.
• This increases volume of the the cavity, which in turn decreases the intrathoracic pressure
allowing the lungs to expand and inspiration to occur.
• The diaphragm is much more than just a sheath separating your thoracic and abdominal
cavities.
• This article will examine this intricate and crucial muscle in detail, looking at its anatomy,
function and structures which pass through it.

Origin Sternal part: Posterior aspect of xiphoid process
Costal part: Internal surfaces of lower costal cartilages and ribs 7-12
Lumbar part: Medial and lateral arcuate ligaments (lumbocostal arches),
bodies of vertebrae L1-L3 (+intervertebral discs), anterior longitudinal
ligament
Insertion Central tendon of diaphragm
Relations Pleural cavities, pericardial sac, liver, right kidney, right suprarenal gland,
stomach, spleen, left kidney, left suprarenal gland
Openings Aortic hiatus (aorta, azygos vein, thoracic duct), esophageal hiatus
(esophagus, vagus nerve), caval foramen (inferior vena cava)
Mnemonic: I 8 10 EGGS AT 12
Greater, lesser, least splanchnic nerves, superior epigastric vessels
Innervation Phrenic nerves (C3-C5) (sensory innervation of peripheries via 6th-11th
intercostal nerves)
Mnemonic: C3, 4, 5 keeps the diaphragm alive!
Blood supply Subcostal and lowest 5 intercostal arteries, inferior phrenic arteries, superior
phrenic arteries

STOMACH
• Synonyms: Gaster (in Greek); enter (in Latin).
• The stomach is the widest and most distensible part of the alimentary canal between the oesophagus and the
duodenum.
• LOCATION
• The stomach is situated in the upper left part of the abdomen occupying left hypochondriac, umbilical, and
epigastric regions. It extends obliquely from the left hypochondriac region into the epigastric region.
• Most of the stomach lies under cover of the left costal margin and lower ribs.
• Shape
• The stomach is mostly “J” shaped.
• Its long axis passes downward, forward, and to the right and finally backward and slightly upward.
• It tapers from the fundus on the left of the median plane to the narrow pylorus slightly to the right of the
median plane.
• N.B.
• • Both the shape and position of the stomach vary greatly according to the build of an individual, it is:
• 1. High and transverse (steer horn type) in short obese Ends persons.
• 2. Low and elongated in tall and weak persons.

• EVEN IN THE SAME INDIVIDUAL THE SHAPE OF THE STOMACH
• 1.Volume of fluid or food it contains.
• 2. Position of body (erect or supine position).
• 3. Phase of respiration.
• The shape of the stomach is studied by radiographic examination using barium
meal.

SIZE AND CAPACITY
• Length: 10 inches.
• Capacity:
• The capacity of the stomach is variable as the stomach is highly distensible:
• 1. At birth the capacity is only 30 ml (1 ounce).
• 2. At puberty the capacity is 1000 ml (1 L).
• 3. In adults the capacity is 1500 to 2000 ml.

EXTERNAL FEATURES
• The stomach presents the following
external features:
• 1. Two ends: Cardiac and pyloric.
• 2. Two curvatures: Greater and lesser.
• 3.Two surfaces: Anterior
(anterosuperior) and posterior
(posteroinferior)

Cardiac orifice Pyloric orifice
It is at the junction between the
lower end of the oesophagus and
stomach, and marks the level at
which curvatures begin
It is at the junction between the
pyloric end of the stomach and first
part of the duodenum
It is situated to the left of the median
plane behind the left 7th costal cartilage,
2.5 cm from its junction with the sternum
at the level of lower border of T11
It is about 1.5 cm to the right of median
plane at the lower border of L1
(i,e.,transpyloric plane)
It does not have an anatomical
sphincter but is guarded by the
physiological sphincter
It has anatomical pyloric sphincter
formed by the thickening of a
circular coat of muscle assisted by a
deep set of longitudinal fibres of the
stomach

ENDS
• Cardiac End (Upper End)
• It joins the lower end of the oesophagus and presents
an depends upon the:
• orifice called cardiac orifice.
• Pyloric End (Lower End)
• It joins the proximal end of the duodenum and
presents an orifice called pyloric orifice.
• The stomach is relatively fixed at upper and lower ends
but mobile in between.
• Cardiac part Body
• The cardiac end of the stomach is less mobile and less
likely to vary in position whereas the pyloric end of the
Pylorus stomach is more mobile and more likely to vary
in position.

CURVATURES
• The stomach presents two curvatures-lesser and greater.
• Lesser Curvature
• It is concave and forms the shorter right border of the stomach.
• The most dependent part of this curvature the angular notch/incisura angularis indicates the
junction of the body and pyloric part.
• The lesser curvature provides attachment to the lesser omentum.
• Greater Curvature
• It is convex and forms the longer left border of the stomach.
• At its upper end this curvature presents a cardiac notch which separates it from the left
aspect of the oesophagus.
• The greater curvature provides attachment to the greater omentum, gastrosplenic, and
gastrophrenic ligaments.

PARTS
• The stomach has four parts:
• 1.Cardiac part (or cardia).
• 2. Fundus.
• 3. Body.
• 4. Pyloric part.

FUNDUS:
• Cardiac Part
• It is the part around the cardiac orifice.
• FUNDUS:
• The fundus is the upper dome-shaped part of the stomach situated above the horizontal plane
drawn at the level of cardiac notch.
• The fundus is generally distended with gas/air, which is clearly seen as a radiolucent shadow
under the left dome of the diaphragm in a skiagram.
• Superiorly,
• the fundus usually reaches the level of the left 5th intercostal space just below the nipple,
hence gastric pain sometimes imitates the pain of angina pectoris.

THE CARDIAC NOTCH
• The cardiac notch
• lies between the fundus and the oesophagus.
• Cardiac notch
• Oesophagus Cardiac end of median plane at the lower border of LI (i.e., transpyloric Plane)
sternum at the level of lower Fundus border of TI1 It is at the junction between and first part
of the Cardiac and pyloric orifices of the stomach
• Cardiac orifice
• Pyloric orifice It is at the junction between the lower end of the oesophagus the pyloric end of
the stomach and stomach, and marks the level at which

RELATIONS
PERITONEAL RELATIONS
• The stomach is covered by the peritoneum except where blood vessels run along its curvatures
and a small area (called bare area of the stomach) posteriorly near the cardiac orifice.
• The bare area of the stomach is directly related to the left crus of the diaphragm.
• The peritoneal folds extending from the lesser and greater curvatures of the stomach to other
structures are as follows:
• 1.Lesser omentum, extends from the lesser curvature of the stomach to the liver.
• 2.Greater omentum, extends from the lower two-third of the greater curvature to the
transverse colon.
• 3. Gastrosplenic ligament, extends from the upper one- third of the greater curvature (i.e.,
fundus) to the spleen (near the hilum).
• 4. Gastrophrenic ligament, extends from the uppermost part of the fundus to the diaphragm.
• Gastrophrenic ligament Bare area of stomach Gastrosplenic ligament Hepatotactic ligament
Lesser omentum Hepatoduodenal ligament Greater omentum

VISCERAL RELATIONS
• 1: Relations of the anterior (anterosuperior) surface:
• (a) On the right side this surface is related to the gastric impression of the left lobe of the
liver and near the pylorus to the quadrate lobe of the liver.
• (b) The left half of this surface is related to the diaphragm the and rib cage.
• (c) The lower part of this surface is related to the anterior abdominal wall.
• Visceral Relations
• 1: Relations of the anterior (anterosuperior) surface:
• (a) On the right side this surface is related to the gastric impression of the left lobe of the
liver and near the pylorus to the quadrate lobe of the liver.
• (b) The left half of this surface is related to the diaphragm the and rib cage.
• (c) The lower part of this surface is related to the anterior abdominal wall.

2. RELATIONS OF THE POSTERIOR (POSTEROINFERIOR) SURFACE:
• 2. Relations of the posterior (posteroinferior) surface:
• This surface is related to a number of structures on Posterior abdominal wall,
• which collectively form the stomach bed.
• These structures are:
• (a) Diaphragm.
• (b) Left kidney.
• (c) Left suprarenal gland.
• (d) Pancreas.
• (e) Transverse mesocolon.
• (f) Left colic flexure (splenic flexure of colon).
• (g) Splenic artery.
• (h) Spleen.
• N.B.
• All the structures forming the stomach bed are separated from the stomach by the lesser sac except spleen,
• which is separated from the stomach by the greater sac of peritoneum.

MICROSCOPIC STRUCTURE
• Stomach wall is formed by four layers of structures:
• 1. Outer serous layer: Formed by peritoneum
• 2. Muscular layer: Made up of three layers of smooth muscle fibers, namely
inner oblique, middle circular and outer longitudinal layers
• 3. Submucous layer: Formed by areolar tissue, blood vessels, lymph vessels
and Meissner nerve plexus.
• 4. Inner mucus layer: Lined by mucus – secreting columnar epithelial cells.
• The gastric glands are situated in this layer.
• Under resting conditions, the mucosa of the stomach is thrown into many
folds.
• These folds are called rugae.
• The rugae disappear when the stomach is distended after meals.
• Throughout the inner mucus layer, small depressions called gastric pits are
present.

MUSCULAR LAYER
• • The muscular coat consists of three layers of
unstriped muscles-outer longitudinal, middle
circular, and inner oblique.
• Close to the pyloric end the longitudinal muscle
coat separates into superficial and deep fibres.
• The deep fibres turn inward at the pylorus and join
with circular muscle coat to help form the pyloric
sphincter.
• The circular muscle coat thickens at the pylorus to
form a Circular muscle of duodenum ring of muscle
called pyloric sphincter.
• The major sphincteric component of the pyloric
sphincter is derived from the circular muscle coat
and its minor dilator component is derived from the
longitudinal muscle coat.

GLANDS OF STOMACH
• ■ CLASSIFICATION OF GLANDS OF THE
STOMACH
• Gastric glands are classified into three types, on the
basis of their location in the stomach:
• 1. Fundic glands or main gastric glands or oxyntic
glands: Situated in body and fundus of stomach
• 2. Pyloric glands: Present in the pyloric part of the
stomach
• 3. Cardiac glands: Located in the cardiac region of
the stomach.

STRUCTURE OF GASTRIC GLANDS
1. FUNDIC GLANDS
• Fundic glands are considered as the typical gastric glands.
• These glands are long and tubular.
• Each gland has three parts, viz. body, neck and isthmus.
• Cells of fundic glands
• 1. Chief cells or pepsinogen cells
• 2. Parietal cells or oxyntic cells
• 3. Mucus neck cells
• 4. Enterochromaffin (EC) cells or Kochanski cells
• 5. Enterochromaffin – like (ECL) cells.
• Parietal cells are different from other cells of the gland because of the presence of canaliculi
(singular = canaliculus).
• Parietal cells empty their secretions into the lumen of the gland through the canaliculi.
• But, other cells empty their secretions directly into lumen of the gland.

• 2. Pyloric Glands
• Pyloric glands are short and tortuous in nature.
• These glands are formed by G cells, mucus cells, EC cells and ECL cells.
• 3. Cardiac Glands
• Cardiac glands are also short and tortuocus in structure, with many mucus cells.
• EC cells, ECL cells and chief cells are also present in the cardiac glands.
• Enteroendocrine Cells Enteroendocrine cells are the hormone – secreting cells present in the
glands or mucosa of gastrointestinal tract, particularly stomach and intestine.
• The enteroendocrine cells present in gastric glands are G cells, EC cells and ECL cells.

FUNCTIONS OF GASTRIC GLANDS
• Function of the gastric gland is to secrete gastric juice. Secretory activities of different cells of
gastric glands and enteroendocrine cells.
• 1. MECHANICAL FUNCTION
• 2.DIGESTIVE FUNCTION
• 3.PROTECTIVE FUNCTION
• 4. HEMOPOIETIC FUNCTION
• 5. EXCRETORY FUNCTION
• Many substances like toxins, alkaloids and metals are excreted through gastric juice.

1. MECHANICAL FUNCTION
• I. Storage Function
• Food is stored in the stomach for a long period, i.e. for 3 to 4 hours and emptied into the
intestine slowly.
• The maximum capacity of stomach is up to 1.5 L.
• Slow emptying of stomach provides enough time for proper digestion and absorption of
food substances in the small intestine.
• ii. Formation of Chyme
• Peristaltic movements of stomach mix the bolus with gastric juice and convert it into the
semisolid material known as chyme.
• EXCRETORY FUNCTION
• Many substances like toxins, alkaloids and metals are excreted through gastric juice.

PROPERTIES OF GASTRIC JUICE
• Volume: 1200 mL / day to 1500 mL / day.
• Reaction:
• Gastric juice is highly acidic with a pH of 0.9 to 1.2.
• Acidity of gastric juice is due to the presence of hydrochloric acid.
• Specific gravity: 1.002 to 1.004 T 1
• ■ COMPOSITION OF GASTRIC JUICE
• Gastric juice contains
• 99.5 % of water and
• 0.5 % solids.
• Solids are organic and inorganic substances.

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