The oral cavity is conveniently divided by the arch formed by the teeth and gums into:1. Oral Vestibule - lies between the gums and the teeth.2. Oral Cavity Proper - lies behind and within the arch of teeth.
THE ORAL VESTIBULE
Boundaries:1. Anteriorly by the lips,2. Laterally by the cheeks,3. Superiorly by the mucolabial and mucobuccal folds, and4. Posteriorly and medially by the teeth and gums.
THE ORAL CAVITY PROPER
Boundaries:1. Anteriorly and laterally by the teeth and gums,2. Superiorly by the palate (hard and soft),3. Inferiorly by the tongue and the floor of the mouth, and4. Posteriorly by the opening into the pharynx.
The Sublingual RegionCharacteristic features:1. Anterior 2/3 of the tongue,2. Lingual frenulum,3. Lingual vein,4. Sublingual caruncle,5. Sublingual folds6. Fimbriated fold
Gums and Gingivae- consist of dense vascular fibrous tissue which is covered by mucous membrane and is attached to the alveolar margins of the jaw.- they are continuous with the mucosa of the oral vestibule externally and the palate or the floor of the mouth internally.
Hard and Soft PalateThe palate forms the superior wall or the roof of the oral cavity proper. It is composed of the hard palate which has an osseous base, and behind, a soft palate composed of fibrous tissue.
THE HARD PALATE
- Covered by mucoperiosteum and forms apartition between the oral and nasal cavities.- mucoperiosteum is thin in the middle but thickerat the sides due to the presence of numerousglands- formed by the palatine process of the maxillaand the horizontal plate of the palatine bone.
Characteristic Features:1. Median raphe is a longitudinal ridge extending from the uvula to the incisive papilla.2. Incisive papilla is a small projection of the mucosa indicating the location of the incisive foramen and the anterior limit of the median raphe.
3. Transverse palatine process or palatine rugae are about six distinct elevation crossing the anterior part of the hard palate.4. Fovea palatine are small inconstant pits on the posterior margin of the hard palate on either side of the median raphe.
THE SOFT PALATE
Is the posterior movable portion of the palate, extending from one side of the pharynx to the other, and attached to the posterior border of the hard palate.
Characteristic Features:1. Uvula is the median conical projection marked by median raphe.2. Palatine arches are free margins of the soft palate and splitting into two parts as they approach the lateral wall. a. Palatoglossal arch or anterior pillar of fauces or anterior palatine arch encloses the palatoglossus muscle. b. Palatapharyngeal arch or posterior pillar of fauces or posterior palatine arch encloses the palatopharyngeus muscle.
Muscles of the Soft Palate Muscle Origin Insertion ActionPalatopharyn- Palatal Lateral wall of Elevates thegeus aponeurosis the pharynx pharynx and and posterior larynx border of the Closes the thyroid cartilage oropharyngeal isthmusPalatoglossus Palatal Dorsum and Closes the aponeurosis lateral aspect of oropharyngeal the tongue isthmusUvular Posterior nasal Uvula Raises the spine uvula to help seal oral from nasal pharynx
Muscles of the Soft Palate Muscle Origin Insertion ActionLevator veli Medial aspect Directly into Elevatespalatini of the auditory the palatine palate during tube aponeurosis swallowing, yawningTensor veli Lateral aspect Tendon hooks Tenses thepalatini of the under hamulus palate and membranous and inserts opens the portion of the into the palatal mouth of auditory tube, aponeurosis auditory tube scaphoid fossa during of the swallowing sphenoid bone and yawning
• A mobile mass of muscles lying on the floor of the mouth and associated with the function of taste, chewing, swallowing, and speaking.
Characteristic features:1. Root is the lower portion of the posterior half of the tongue through which the extrinsic muscles, blood vessels and nerves become connected with the organ. It is attached to the mandible and the hyoid bone
2. Body anterior part of the tongue, made up of interlacing skeletal muscles.3. Margins are the lateral portion of the tongue, free and blunt, in relation to the gums and teeth.4. Tip or apex is the pointed and free anterior end.5. Inferior surface is seen when the tongue is turned upwards.
6. Dorsum linguae is slightly convex antero-posteriorly, divided into 2 parts by a V- shaped groove – the SULCUS TERMINALIS or LINEA TERMINALIS. Parts: a. Palatine part is visible when the mouth is opened, covered by papillae. b. Median sulcus is a faint groove separating the palatine part into symmetrical parts. c. Foramen caecum is a small pit at the apex of the sulcus terminalis. d. Pharyngeal part is the posterior 2/3s of the tongue which contains serous glands and nodules of lymphoid tissue – LINGUAL FOLLICLES. e. Glosso-epiglottic fold is the reflection of the mucous membrane of the tongue on to the epiglottis producing elevation.
THE LINGUAL PAPILLAE
1. Vallate or circumvallate papillae are the largest, numbering from 7-12, and are arranged in front of the sulcus terminalis.2. Fungiform papillae are fewer in number and are limited to the tip and margins of the tongue.3. Filiform papillae are the smallest and the most numerous, scattered all over the anterior 2/3 of the dorsum of the tongue.
The Taste Buds- are receptor organs for the specialsensation of taste. They are pale oval bodiesmost of which are located surrounding thevallate papillae; a few are found on thefungiform and foliate papillae. A few tastebuds are scattered through the epithelium ofthe oral surface of the soft palate, theposterior wall of the pharynx, and theepiglottis.
The Muscles of the TongueExtrinsic muscles are responsible for changing position of the tongue. Muscle Origin Insertion ActionGenioglossus Genial tubercle Tongue Retract and of mandible depress the tongueHyoglossus Hyoid bone Posterior half of Depress the the side of the tongue tongueStyloglossus Styloid process Whole length of Pull the tongue of temporal the tongue upwards and bone backwards
The Muscles of the TongueThe Intrinsic Muscles: 1. Superior and inferior longitudinal muscles - Located close to the dorsum of the tongue - Shorten the length of the tongue and to curl the tip of the tongue and back. 2. Transverse muscles - narrows the tongue. 3. Vertical muscles - flattens the tongue.
A Summary of the Actions of the Tongue1. Protrussion : genioglossus2. Retrussion : hyoglossus, styloglossus, genioglossus3. Depression : genioglossus, hyoglossus4. Elevation : styloglossus5. Shortening : longitudinal intrinsic fibers6. Narrowing : transverse intrinsic fibers7. Flattening : vertical intrinsic fibers
Paralyzed Tonguea fractured mandible may damage thehypoglossal nerve to pull the tongue to thesame side. General anesthesia results inlooseness, or flaccidity, of muscles. Aparalyzed or flaccid tongue tends to fall backinto the airway, causing suffocation, unless apatent airway is maintained.
Tongue TieA large lingual frenulum can limit the mobility of the tongue and interfere with speech. The condition is easily repaired by cutting the frenulum (lingual frenectomy).
The Salivary Glands andAccessory Glands of the Oral Cavity
The Salivary Glands of the Oral Cavity1. Parotid Gland2. Submandibular Gland3. Sublingual Gland
The Parotid Gland
The Parotid GlandThe parotid gland is one of the three major salivary glands that produce and secrete saliva for the oral cavity.weight: about 14 to 28 g.color :yellowish in the fresh statecomposition: serous secreting units
Location and Relations of the Parotid GlandA. Anterior surface: lies against the posterior border of the ramus of the mandibleB. Posterior surface: on the external auditory meatus and sternocleidomastoid muscle
B. Superficial surface: lobulated, covered by skin, fascia, lymph nodes, and facial branches of the great auricular nerve.C. Deep surface: styloid process and its muscles as well as under the mastoid and sternocleidomastoid muscles.
Capsule of the Parotid Gland-The gland is wrapped in a fibrous capsule, which is continuous with the deep investing fascia of the neck.-The stylomandibular ligament is an anterior thickening of the capsule, which runs from the styloid process to the angle of the mandible. –-It separates the parotid gland from the infratemporal fossa anteriorly and separates the parotid gland from the submandibular gland inferiorly and anteriorly.
The Parotid DuctFrom the rostral border of the gland, crosses masseter muscle, turns inward to pierce the fat pad of the cheek and then the buccinator muscle, to open into the mouth opposite the second maxillary molar. Approximately 5 cm. long.
1. A viral inflammation of the parotid gland (mumps) causes it to swell, resulting to pain on movement of the jaw.2. Abcesses or cysts of the gland may result in pressure to the facial nerve3. Stones or calculi in the duct can block it, causing painful swelling of the gland.
The Submandibular Gland
Type:It is a mixed serous and mucous secreting gland.Location:It is found partly in the submandibular fossa below the mylohyoid muscle and partly in the floor of the mouth.
Duct:The submandibular duct (Wharton’s) arises from the medial surface of the gland and accompanies it under the mlohyoid muscle; it passes diagonally across the medial aspect of the sublingual gland and adheres to it. It opens at the sublingual papillae (sublingual caruncle) beside the base of the lingual frenulum.
The Sublingual Gland
The smallest of the three major salivary glands and rests upon the mylohyoid muscle in the sublingual fossa close to the symphysis. It is primarily a mucous secreting gland.
Location: The gland, indicated by the subligual fold is found between the alveolus and the anterior part of the tongue.Ducts: The gland has many lesser sublingual ducts (Rivini’s) that opens separately at the floor of the mouth and a greater sublingual duct (Bartholin’s) that opens on the sublingual caruncle together with the Wharton’s duct.
The Accessory Glands
The Accessory GlandsBeside the main salivary glands, many othersexists: some in the tongue, others around andin the palatine tonsil between its crypts, withthe large number in the soft palate, theposterior part of the hard palate, the lips andthe cheeks. These are similar in structure tolarger salivary glands and are mainly mucoustype.