Anatomy of Respiratory system for MD [Autosaved].ppt

by Abera N (MSC)
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Anatomy of
RESPIRATORY system

 Gross anatomy of respiratory system
 Development of respiratory system
 The Histology of respiratory system
THE RESPIRATORY anatomy
by Abera N (MSC)
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Outlines
 Introduction
 Overview of the respiratory system
 Thoracic wall
 The upper respiratory system
 The nose
 The pharynx
 The Lower respiratory system
 The larynx
 The trachea
 the bronchi
 The lungs
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Overview of the respiratory system
Definition:-
 Respiration is a term used to describe two different but interrelated
processes:
• External (mechanical) respiration
 the absorption of O₂ and removal of CO₂ from the body as a whole
• Internal (Cellular) respiration
 the utilization of O₂ and production of CO₂ by cells and the gaseous exchanges
between the cells and their fluid medium
 the series of intracellular biochemical processes by which the cell produces
energy by metabolism of organic molecules
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 The respiratory system is made up of air conducting
organs (nose, pharynx, larynx, trachea and bronchial
tree), a gas-exchanging organ (lungs), and a pump that
ventilates the lungs
 Inhalation and exhalation are achieved by expanding and
contracting the thoracic cavity using the intercostal
muscles and the diaphragm, drawing air in when the
thoracic cavity expands and driving air out when it
contracts
 The pump consists of the chest wall; the respiratory
muscles, which increase and decrease the size of the
thoracic cavity; the areas in the brain that control the
muscles; and the tracts and nerves that connect the
brain to the muscles
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 At rest, a normal human breathes 12–15 times
a minute
 About 500 mL of air per breath, or 6–8 L/min,
is inspired and expired
 This air mixes with the gas in the alveoli, and,
by simple diffusion, O₂ enters the blood in the
pulmonary capillaries while CO₂ enters the
alveoli
 In this manner, 250 mL of O₂ enters the body
per minute and 200 mL of CO₂ is excreted
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Respiration
 Goals: to provide oxygen to the tissues and to remove
carbon dioxide
 To achieve these goals, respiration can be divided into
four major functions:
 Pulmonary ventilation
 Air moves in and out of lungs
 Continuous replacement of gases in alveoli (air sacs)
 External respiration
 Gas exchange between blood and air at alveoli
 O2 (oxygen) in air diffuses into blood
 CO2 (carbon dioxide) in blood diffuses into air
 Transport of respiratory gases
 Between the lungs and the cells of the body
 Performed by the cardiovascular system
 Blood is the transporting fluid
 Internal respiration
 Gas exchange in capillaries between blood and tissue cells
 O2 in blood diffuses into tissues
 CO2 waste in tissues diffuses into blood
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 External (Mechanical) respiration involves the following
steps:
 Air is drawn into the body (to the lungs) from the
atmosphere by inhalation
 Before it reaches the furthest parts of the lungs the air is
cleaned by removal of particulate matter, warmed so that
its temperature equals that of the body, and moistened
 Gas exchange takes place in the lung
 In the lung parenchyma, oxygen is extracted from the air and
transferred into the blood vascular system where it bonds tightly
with haemoglobin in the red cells for transport in the systemic
arterial circulation
 At the same time that oxygen is passing from air into the blood,
carbon dioxide (a side product of cellular metabolic activity) is
transferred from the blood to the air
 After gaseous exchange, the air is returned to the
atmosphere by exhalation
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Other Functions of the Respiratory System
 Regulation of blood pH
 The respiratory system can alter blood pH by
changing blood carbon dioxide levels
 Voice production
 Air movement past the vocal folds makes sound and
speech possible
 Olfaction
 The sensation of smell occurs when airborne
molecules are drawn into the nasal cavity
 Protection
 The respiratory system provides protection against
some microorganisms by preventing their entry into
the body and by removing them from respiratory
surfaces
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Thoracic wall
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A.THE WALL OF THE THORAX
by Abera N (MSC)
 Osteocartilageno
us
+
 Muscular
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The Thorax
 The thoracic cavity, surrounded by
the thoracic wall, contains the heart,
lungs, thymus, distal part of the
trachea, and most of the esophagus.
 The thoracic wall consists of skin, fascia, nerves,
vessels, muscles, and bones.
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The Thorax
Functions of the thoracic wall include:
 protecting of thoracic & abdominal internal organs;
Resisting negative internal pressures generated by
elastic recoil of the lungs & inspiratory movements;
providing attachment for and supporting the weight of
the upper limbs.
It provides attachment for muscles of upper limbs,
neck, abdomen & back, & muscles of respiration.
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Skeleton of Thoracic Wall
 thoracic skeleton forms osteocartilaginous thoracic
cage .
 thoracic skeleton (bony thorax) includes;
-12 pairs of ribs and costal cartilages,
-12 thoracic vertebrae & intervertebral discs
- sternum.
 Costal cartilages form the anterior continuation of the
ribs, providing a flexible attachment at their
articulation with the sternum .
 Ribs & their cartilages are separated by intercostal
spaces, containing intercostal muscles, vessels, and
nerves.
by Abera N (MSC)
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Ribs:
 The ribs are curved, flat bones that form most of the thoracic
cage .
 They are remarkably light in weight yet highly resilient.
 There are three types of ribs:
1. True (vertebrocostal) ribs (1st- 7th ribs) attach directly to
the sternum through their own costal cartilages.
2.False (vertebrochondral) ribs (8th -10th ) ribs) have
cartilages that are joined to the rib just superior to them;
thus, their connection with the sternum is indirect.
3.Floating (free) ribs (11th- 12th ribs) have rudimentary
cartilages that do not connect even indirectly with the
sternum;  instead, they end in the posterior abdominal
musculature.
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Ribs:
 Typical ribs (3rd - 9th) have a:
 Head: that is wedge-shaped and two facets that are separated by the
crest of the head . One facet is for articulation with the numerically
corresponding vertebra, and one facet is for the vertebra superior to
it.
 Neck: that connects the head with the body at the level of the
tubercle.
 Tubercle: at the junction of the neck and body. The tubercle has a
smooth articular part for articulating with the corresponding
transverse process of the vertebra and a rough non-articular part for
the attachment of the costotransverse ligament.
 Body (shaft): that is thin, flat, and curved, most markedly at the
angle where the rib turns anterolaterally.
 The concave internal surface has a costal groove that protects the
intercostal nerve and vessels .
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Typical & Atypical ribs
Atypical ribs (1st, 2nd, & 10th - 12th) :
 The 1st rib: is the broadest (its body is widest & nearly horizontal),
shortest, & most sharply curved of the seven true ribs;
 it has two grooves crossing its superior surface for the subclavian
vessels.
 has scalene tubercle
 The 1st rib has single facet.
 The 2nd rib: is thinner, less curved & much longer than 1st rib.
 It has two facets on its head for articulation with the bodies of the
T1 and T2 vertebrae.
 has tuberosity for serratus anterior muscle
 The 10th -12th ribs, like the 1st rib, have only one facet on their
heads.
 The 11th and 12th ribs are short and have no necks or tubercles.
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Typical & Atypical Ribs
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Typical & Atypical Ribs
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Costal cartilages:
 prolong the ribs anteriorly and contribute to the elasticity
of the thoracic wall.
Intercostal spaces:
 separate the ribs and their costal cartilages from one
another.
 spaces and neurovascular structures are named
according to the rib forming the superior border of the
space.
 there are 11 intercostal spaces and 11 intercostal nerves.
 The subcostal space is below the 12th rib and the anterior
ramus of spinal nerve T12 is the subcostal nerve.
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Applied Anatomy
 Variation of ribs
• Number: increased by development of cervical or lumbar ribs or
decreased by failure of the 12th rib to develop
• Shape: bifid ribs
 Angle of ribs are their weakest point
 Flail chest (‘stove-in chest’): multiple rib fracture
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Thoracic Vertebrae:
 There are 12 thoracic
vertebrae:
1st & 12th are called atypical
and the rest are typical.
All of the typical vertebrae
have same characteristics.
The 1st and 12th vertebrae
have slightly different
characteristics than the typical
ones.
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Thoracic Vertebrae:
 are typical vertebrae in that: they are independent, they
have bodies, vertebral arches & seven processes for
muscular & articular connections .
Characteristic features of thoracic vertebrae include:
 All thoracic vertabrae form joints with the ribs
Thoracic vertabrae from 2-8 have similar characterstics
(contain superior & inferior costal demifacets on
posterolateral aspect of their bodies for the articulations with
head of ribs) : Thus, they are typical thoracic vertabrae.
 The first and the 9th-12th contain single costal facet.
 The 11th and12th thoracic vertebrae contain one costal
facet& no transverse costal facet for the 11th and12th ribs
respectively.
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Characteristics of a typical thoracic
vertebra include:
 body (1)
 superior & inferior demifacets (2,3)
 pedicle (4)
 superior & inferior articular processes
(5, 6)
 transverse process (with an articular
process) (7,10)
 lamina (8)
 spinous process (9)
 superior and inferior notches (13,12)
 vertebral canal(14)
 intervertebral disk (11)  is not a bone
but an integral part of vertebral column
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Thoracic Vertebrae
• Typical: T2-T8
• Body is larger than
cervical; heart
shaped
• Spinous process is
long and sharp,
projects inferiorly
• Vertebral foramen is
circular
• T1: has long,
horizontal spinous
process
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Thoracic Vertebrae
• Transverse processes
project posteriorly
and bear costal facets
for ribs (T1-T10)
• Body bears two costal
demifacets (T2-T8)
• Superior – articulate
with head of its own rib
• Inferior - articulate
with head of the rib
inferior to it
• T1: has complete facet
superiorly
• T10-T12: have one
facet
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Thoracic Vertebrae:
Other important features of thoracic vertebrae
are the following:
 Their bodies are shorter venterally than dorsally
 Their articular processes are more or less vertical.
 The spinous process are curved downward
 They contain circular vertebral foramina
 Their transverse processes bear costal facets for
the articulation with the tubercles of the ribs.
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Sternum:
 The sternum is the flat,
vertically elongated bone
that forms the middle of
the anterior part of the
thoracic cage.
 The sternum consists of
three parts: manubrium,
body, and xiphoid
process
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Surface Anatomy of the Thorax:
Sternum-
 lies subcutaneously in the anterior median line and is palpable
through out its length.
Jugular notch (superasternal notch)
 easily palpated concave center of superior border of manbrium.
 The notch lies at level of inferior border of body of T2 vertebra &
space b/n 1st & 2nd thoracic spinous processes.
Manubrium: -
 upper part of sternum, approximately 4cm long,
 lies at level of bodies of T3 & T4 vertebrae.
• Inferior border articulate with body; forms
projection – sternal angle
• Landmark to several structures
• Lies opposite 2nd costal cartilage: guide to
numbering of ribs

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 Body
 Located at level of T5-T9
 Lateral wall has costal notches
 Marked by 3 transverse ridges – lines of fusion
 Xiphoid process
 Sword-shaped
 Cartilage at birth and ossify at middle adulthood
 Landmark: inferior limit of thoracic cavity, inferior
border of heart etc
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Surface Anatomy of the Thorax…
Strenal angle (angle of luois) –
 lies at level of T4 – T5 Intervertebral disc & space b/n 3rd & 4th
thoracic spinous processes.
 Marks level of 2nd pair of costal cartilage at manubrostrnal
joint.
 trachea bifurcates into the main (primary) bronchi at this angle
(or at level of transverse thoracic plane).
 arch of aorta (begins posterior to 2nd right sternocostal joint) and
thoracic aorta begin at level of sternal angle.
Body of sternum: -
 aproximately10 cm long;
 lies anterior to right border of the heart & vertebrae T5 - T9.
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Xiphoid process:-
 lies in a slight depression, epigastric fossa, where converging costal
margins form infrasternal (sub costal) angle.
 lies at the level of T10 vertebra.
 The costal margins form the sides of the infrasternal angle.
 This angle is used in cardiopulmonary resuscitation (CPR) for
locating proper hand position on inferior part of sternal body
 It is an important landmark in the median plan because:
 Its junction with sternal body at xiphisternal joint (at level of
inferior border of T9 vertebra) indicates the inferior limit of
central part of thoracic cavity.
 A midline marker for superior limit of liver, central tendon of
diaphragm & inferior border of the heart.
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Costal margins:
•formed by the joined costal
cartilage of 7th – 10th costal
cartilages,
•are easily palpable
because they extend
anterorlaterlly from the
xiphisternal joint.
• costal margins form the
sides of infrasternal angle.
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Imaginary Lines: facilitate anatomical & clinical
description of the body
 The following lines are extrapolated over the thoracic wall
based on visible or palpable superficial features:-
Anterior median (midsternal) line (AML) –
 Indicates intersection of the median plane with the
anterior thoracic wall.
Mid clavicualr line (MCL) –
 passes thru mid point of clavicle, parallel to the AML.
Anterior axillary line (AAL) –
 runs vertically along anterior axillary fold that is formed by
inferolateral border of pectoralis major.
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Mid axillary line (MAL) –
 runs from apex (deepest part) of axillary fossa, parallel to AAL.
Posterior median line (PML) –
 a vertical line along tips of spinous process of the vertebrae.
Posterior axillary line (PAL) –runs vertically along posterior axillary
fold that is formed by latissimus dorsi & teres major m
Scapular line (SL) – is parallel to the posterior median line &
intersects inferior angles of scapula.
Additional lines-
 Para sternal & Para vertebral lines: are extrapolated along
borders of palpable bony formations of sternum & vertebral
column.
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the Thoracic Wall
 Thoracic wall is made up of sternum, ribs plus three
layers of intercostal muscles, diaphragm &
intercostal vessels and nerves.
 Inside of thoracic wall is lined by Endothoracic Fascia.
 Muscles of the thorax consist of the intercostals and
diaphragm.
 Intercostal muscles are arranged as three layers
(external layer, internal layer and an incomplete
innermost layer) b/n the ribs.
 Diaphragm closes the thoracic outlet and separates the
thoracic cavity from the abdominal cavity.
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Muscles of the Thoracic Wall
 Several upper limb (thoracoappendicular) muscles
attach to the thoracic cage - including the pectoralis
major, pectoralis minor, subclavius, and serratus
anterior muscles anteriorly and latissimus dorsi
muscles posteriorly as do the anterolateral abdominal
muscles and some back and neck muscles
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The intercostal muscles
 The intercostal muscles occupy the intercostal spaces
 The superficial layer is formed by the external
intercostals, the inner layer by the internal intercostals
 The deepest layers: lying internal to the intercostal
vessels are the innermost intercostals
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Muscles of the Thoracic Wall
 The three layers of the intercostal muscles are:
 external layer -- external intercostal
 internal layer -- internal intercostal
 innermost layer -- transversus thoracic (anterior),
innermost (lateral) and subcostal (posterior).
 The diaphragm is the most important muscle of the
thoracic wall: primary component of normal/silent
respiration.
 innermost layer is split into transversus thoracis,
innermost intercostal and subcostal muscles & these
make up the deepest layer of muscles from anterior to
posterior, respectively.
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muscles
 11 pairs occupy the
intercostal spaces from
the tubercles of the ribs
posteriorly to the
costochondral junctions
anteriorly
 Anteriorly, the muscle
fibers are replaced by the
external intercostal
membranes
 Run inferoanteriorly from
the rib above to the rib
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External intercostal
Superior attachment:
 Inferior border of ribs above
Inferior attachment:
 Superior border of ribs below
Innervation:
 Intercostal nerve
Main action:
 Elevate ribs during forced inspiration
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The internal intercostal muscles
 11 pairs, run deep to and at right angles to the external
intercostals
 Their fibers run inferoposteriorly from the floors of the
costal grooves to the superior borders of the ribs
inferior to them
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 The internal intercostals
attach to the bodies of
the ribs and their costal
cartilages as far
anteriorly as the
sternum and as far
posteriorly as the angles
of the ribs
 Between the ribs
posteriorly, medial to the
angles, the internal
intercostals are
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 The inferior internal intercostals are continuous with
the internal oblique muscles in the anterolateral
abdominal wall
 Weaker than the external intercostal muscles
 Are most active during expiration
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Internal intercostal
 Inferior border of ribs
Innervation:
Main action:
 Interosseous part: depresses ribs
 Interchondral part: elevates ribs
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The innermost intercostal muscles
 Are similar to the internal intercostals and
are essentially their deeper parts
 Are separated from the internal
intercostals by the intercostal nerves and
vessels
 Pass between the internal surfaces of
adjacent ribs and occupy the lateral most
parts of the intercostal spaces
 It is likely that their actions are the same
as those of the internal intercostal
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Innermost intercostal
 Inferior border of ribs
Innervation:
Main action:
 Interosseous part: depresses ribs
 Interchondral part: elevates ribs
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The subcostal muscles
 Are variable in size and shape, usually being
well developed only in the lower thoracic wall
 Extend from the internal surface of the angle
of one rib to the internal surface of the 2nd or
3rd rib inferior to it
 Crossing one or two intercostal spaces, the
subcostals run in the same direction as the
internal intercostals and blend with them
 Act with the internal intercostals, and that they
may depress ribs
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Subcostal muscle
 Internal surface of lower ribs near their
angles
 Superior borders of 2nd or 3rd ribs below
Nerve supply:
Main action:
 Probably act in same manner as internal
intercostal muscles
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The transverse thoracic
 Consist of four or five slips that attach
posteriorly to the xiphoid process, the
inferior part of the body of the sternum, and
the adjacent costal cartilages
 They pass superolaterally and attach to the
2nd - 6th costal cartilages
 Are continuous inferiorly with the transverse
abdominal muscles in the anterolateral body
wall
 Have a weak expiratory function, they may
provide proprioceptive information.
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Transversus thoracis
 Posterior surface of lower sternum
 Internal surface of costal cartilages 2-6
Nerve supply:
Main action:
 Weakly depress ribs, Proprioception?
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Fascia of the Thoracic Wall
 Each part of the deep fascia is named for the
muscle it invests or the structure(s) to which
it is attached
 Consequently, a large portion of the deep
fascia overlying the anterior thoracic wall,
forming a major part of the bed of the breast,
is called pectoral or pectoralis fascia for its
association with the pectoralis major
muscles
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Fascia of the Thoracic Wall
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 The thoracic cage is lined internally with endothoracic
fascia
 This thin fibroareolar layer attaches the adjacent
portion of the costal parietal pleura to the thoracic wall
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Anterior Axioappendicular Muscles of the
UL
 Are 4 in number:
- Pectoralis major
- Pectoralis minor
- Subclavius and
- Serratus anterior
 Move the pectoral girdle
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The Pectoralis Major
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 Is fan-shaped muscle that covers the
superior part of the thorax
 It has two-heads: clavicular and
sternocostal heads
 The sternocostal head is much larger
 The pectoralis major and adjacent deltoid
form the narrow deltopectoral groove, in
which the cephalic vein runs ; however, the
muscles diverge slightly from each other
superiorly and, along with the clavicle, form
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PECTORALIS MAJOR cont’d…
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 Origin:
-Clavicular head: anterior surface of medial half of
clavicle
-Sternocostal head: anterior surface of sternum,
superior six costal cartilages, aponeurosis of external
oblique muscle
 Insertion: Lateral lip of intertubercular groove of
humerus
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PECTORALIS MAJOR cont’d…
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 Nerve supply: Lateral and medial
pectoral nerves
 Main Action: Adducts and medially
rotates humerus
Acting alone:
- Clavicular head flexes humerus and
- Sternocostal head extends it from the
flexed position
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THE PECTORALIS MINOR
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 Is almost completely covered by the much larger
pectoralis major
 Is triangular in shape
 Is a useful anatomical and surgical landmark for
structures in the axilla
 With the coracoid process, the pectoralis minor forms a
bridge under which vessels and nerves must pass to
the arm
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PECTORALIS MINOR cont’d…
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 Origin: 3rd - 5th ribs near their costal cartilages
 Insertion: Medial border and superior surface of
coracoid process of scapula
 Nerve Supply: Medial pectoral nerve
 Main Action: Stabilizes scapula by drawing it inferiorly
and anteriorly against thoracic wall
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ABSCENCE OF PECTORAL MUSCLES
Poland syndrome:
 Both the pectoralis major and minor are absent
 Breast hypoplasia usually occurs
 Absence of two to four rib segments are also seen
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THE SUBCLAVIUS
 Small, round muscle located inferior to
the clavicle
 Lies almost horizontally when the arm is in
the anatomical position
 Affords some protection to the subclavian
vessels and the superior trunk of the
brachial plexus if the clavicle fractures
 The subclavius anchors and depresses
the clavicle
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SUBCLAVIUS
 Origin: Junction of 1st rib and its costal
cartilage
 Insertion: Inferior surface of middle third
of clavicle
 Nerve Supply: Nerve to subclavius
 Main Action: Anchors and depresses
clavicle
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THE SERRATUS ANTERIOR
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 Overlies the lateral part of the thorax
 Is broad sheet of thick muscle
 So named because of the saw toothed
appearance of its fleshy slips or digitations
(L. Serratus, a saw)
 Is one of the most powerful muscles of the
pectoral girdle
 It is a strong protractor of the scapula that
is used when punching (sometimes called
the boxer's muscle)
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SERRATUS ANTERIOR
 Origin: External surfaces of lateral parts of 1st
- 8th ribs
 Insertion: Anterior surface of medial border of
scapula
 Nerve Supply: Long thoracic nerve
 ACTION:
- Protracts scapula and holds it against
thoracic wall
- Rotates scapula
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Paralysis of the Serratus Anterior
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 Is owing to injury to the long thoracic nerve
 The medial border of the scapula moves laterally and
posteriorly away from the thoracic wall, giving the
scapula the appearance of a wing, thus “winging of
scapula’’
 Weapons, including bullets directed toward the thorax,
are a common source of injury
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Nerves of the Thoracic Wall
 The 12 pairs of thoracic spinal nerves supply the
thoracic wall
 As soon as they leave the IV foramina in which they
are formed, the mixed thoracic spinal nerves divide
into anterior and posterior primary rami
 The anterior rami of nerves T1- T11 form the
intercostal nerves that run along the extent of the
intercostal spaces
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Nerves of the Thoracic Wall
 The anterior ramus of nerve T12,
coursing inferior to the 12th rib, is the
subcostal nerve
 The posterior rami of thoracic spinal
nerves pass posteriorly, immediately
lateral to the articular processes of the
vertebrae , to supply the joints, muscles,
and skin of the back in the thoracic region
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Typical Intercostal Nerves
 The 3rd - 6th intercostal nerves enter the medial-most
parts of the posterior intercostal spaces, running
initially within the endothoracic fascia between the
parietal pleura and the internal intercostal membrane
nearly in the middle of the intercostal spaces
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 Near the angles of the ribs, the nerves pass between
the internal intercostal and the innermost intercostal
muscles
 At this point, the intercostal nerves pass to and then
continue to course within the costal grooves, running
inferior to the intercostal arteries (which, in turn, run
inferior to the intercostal veins)
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 The neurovascular bundles are thus
sheltered by the inferior margins of the
overlying ribs
 Collateral branches of these nerves arise
near the angles of the ribs and run along the
superior border of the rib below
 The nerves continue anteriorly between the
internal and the innermost intercostal
muscles, giving muscular branches and
giving rise to lateral cutaneous branches in
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 Anteriorly, the nerves appear on the internal surface of
the internal intercostal muscle
 Near the sternum, the intercostal nerves turn anteriorly,
passing between the costal cartilages to become
anterior cutaneous branches.
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The branches of a typical intercostal
nerve
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 Rami communicantes/communicating
branches: that connect each intercostal
nerve to the ipsilateral sympathetic trunk
 Presynaptic fibers: leave the initial
portions of the anterior ramus of each
thoracic (and upper lumbar) spinal nerve by
means of a white communicating ramus
and pass to the sympathetic trunk
93

nerve
 Postsynaptic fibers: distributed to the body
wall and limbs pass from the ganglia of the
sympathetic trunk via gray rami to join the
anterior ramus of the nearest spinal nerve,
including all intercostal nerves
 Sympathetic nerve fibers are distributed
through all branches of all spinal nerves
(anterior and posterior rami) to reach the
blood vessels, sweat glands, and smooth
muscle of the body wall and limbs
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nerve
 Collateral branches: that arise near the
angles of the ribs and descend to course
along the superior margin of the lower rib,
helping supply intercostal muscles and
parietal pleura
 Lateral cutaneous branches: that arise near
the MAL and pierce the internal and external
intercostal muscles approximately halfway
around the thorax
 The lateral cutaneous branches divide in turn
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nerve
 Anterior cutaneous branches: that supply
the skin on the anterior aspect of the thorax
and abdomen
 After penetrating the muscles and
membranes of the intercostal space in the
parasternal line, the anterior cutaneous
branches divide into medial and lateral
branches.
 Muscular branches: that supply the
intercostal, subcostal, transverse thoracic,
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100
Branches
• Muscular to
− Intercostals
− Subcostal
− Transversus thoracis
− Levator costarum
− Serratus posterior
• Collateral
− supply intercostal
muscles and parietal
pleura
• Cutaneous
− anterior + lateral
• Communicating
− connect each nerve
to sympathetic trunk
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Atypical Intercostal Nerves
 The anterior ramus of the 1st thoracic (T1)
spinal nerve first divides into:
- a large superior and
- a small inferior part
 The superior part: joins the brachial
plexus, the nerve plexus supplying the
upper limb, and
 The inferior part: becomes the 1st
intercostal nerve
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by Abera N (MSC)
 The 1st intercostal nerve has no anterior cutaneous
branch and often no lateral cutaneous branch
 When there is a lateral cutaneous branch, it supplies
the skin of the axilla and may communicate with either
the intercostobrachial nerve or the medial cutaneous
nerve of the arm
102

by Abera N (MSC)
 The 1st and 2nd intercostal nerves course on the
internal surface of the 1st and 2nd ribs, instead of
along the inferior margin in costal grooves
103

 The 2nd intercostal nerve gives rise to a large lateral
cutaneous branch, the intercostobrachial nerve: it
emerges from the 2nd intercostal space at the MAL,
penetrates the serratus anterior, and enters the axilla
and arm
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 The intercostobrachial nerve usually supplies the floor
and skin of the axilla and then communicates with the
medial brachial cutaneous nerve to supply the medial
and posterior surfaces of the arm
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 The 7th- 11th intercostal nerves, after giving
rise to lateral cutaneous branches, cross the
costal margin posteriorly and continue on to
supply abdominal skin and muscles
 No longer being between ribs (intercostal),
they now become the thoracoabdominal
nerves of the anterior abdominal wall
 Their anterior cutaneous branches pierce the
rectus sheath, becoming cutaneous close to
the median plane.
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Vasculature of the Thoracic Wall
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Arteries of the Thoracic Wall
The arterial supply to the thoracic wall
derives from the:
 Thoracic aorta: through the posterior
intercostal and subcostal arteries
 Subclavian artery: through the internal
thoracic and supreme intercostal arteries
 Axillary artery: through the superior and
lateral thoracic arteries
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Arteries of the Thoracic Wall
 The intercostal arteries course through the
thoracic wall between the ribs
 With the exception of the 10th and 11th
intercostal spaces, each intercostal space is
supplied by three arteries:
-a large posterior intercostal artery (and its
collateral branch) and
- a small pair of anterior intercostal arteries
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Posterior intercostal arteries
 Of the 1st and 2nd intercostal spaces arise from the
supreme (superior) intercostal artery, a branch of the
costocervical trunk of the subclavian artery
 Of the 3rd- 11th intercostal spaces (and the subcostal
arteries of the subcostal space) arise posteriorly from
the thoracic aorta
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 Because the aorta is slightly to the left of
the vertebral column, the right 3rd-11th
intercostal arteries have a longer course
than those on the left side
 The right arteries cross the vertebrae and
pass posterior to the esophagus, thoracic
duct, azygos vein, and the right lung and
pleura
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 All give off a posterior branch that
accompanies the posterior ramus of the
spinal nerve to supply the spinal cord,
vertebral column, back muscles, and skin
 Give rise to a small collateral branch that
crosses the intercostal space and runs along
the superior border of the rib
 Accompany the intercostal nerves through
the intercostal spaces
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 Close to the angle of the rib, the arteries
enter the costal grooves, where they lie
between the intercostal vein and nerve
 At first the arteries run in the endothoracic
fascia between the parietal pleura and the
internal intercostal membrane; then they run
between the innermost intercostal and
internal intercostal muscles
 Have terminal and collateral branches that
anastomose anteriorly with anterior
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The internal thoracic arteries
 Arise in the root of the neck from the inferior
surfaces of the first parts of the subclavian
arteries
 Descend into the thorax posterior to the
clavicle and 1st costal cartilage
 Are crossed near their origins by the
ipsilateral phrenic nerve
 Descend on the internal surface of the thorax
slightly lateral to the sternum and posterior to
the upper six costal cartilages and intervening
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126
Internal
Intercostal m
Transversus
Thoracis
Internal thoracic A
Muscolophrenic
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The internal thoracic arteries
 After descending past the 2nd costal cartilage,
the internal thoracic artery runs anterior to the
transverse thoracic muscle
 Between slips of the transverse thoracic
muscle, the artery contacts parietal pleura
posteriorly
 Terminate in the 6th intercostal space by
dividing into the superior epigastric and the
musculophrenic arteries
 Directly give rise to the anterior intercostal
arteries supplying the superior six intercostal
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Ipsilateral pairs of AIAs
 Of the 7th - 9th intercostal spaces derive
from the musculophrenic arteries
 Supply the intercostal muscles and send
branches through them to supply the
pectoral muscles, breasts, and skin
 Are absent from the inferior two
intercostal spaces: these spaces are
supplied only by the posterior intercostal
arteries and their collateral branches
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• Termination - divide in the 6th intercostal space
into
– Superior epigastric artery (which enters the rectus
sheath inferiorly) and
– Musculophrenic artery (which follows the attachment
of the diaphragm to the ribs)
• Also sends branches to the thymus, bronchi and
pericardium
• Branches
– Pericardiacophrenic – accompany phrenic nerve to
supply pericardium
– Mediastinal – supply anterior pericardium, fat and
thymus
– Perforating – to breast
– Anterior intercostals
– Superior epigastric
– Musculophrenic
131 by Abera N (MSC)

Internal thoracic veins
 Accompany the arteries (venae comitantes)
 Unite in upper three intercostal space and drain
into brachiocephalic vein

Veins of the Thoracic Wall
 The intercostal veins accompany the intercostal
arteries and nerves and lie most superior in the costal
grooves
 There are 11 posterior intercostal veins and one
subcostal vein on each side
 The posterior intercostal veins anastomose with the
anterior intercostal veins (tributaries of internal thoracic
veins)
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 As they approach the vertebral column, the posterior
intercostal veins receive a posterior branch, which
accompanies the posterior ramus of the spinal nerve of
that level, and an intervertebral vein draining the
vertebral venous plexuses
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 The posterior intercostal veins of the 1st
intercostal space usually enter directly into the
corresponding and nearby brachiocephalic
veins
 The posterior intercostal veins of the 2nd and
3rd intercostal spaces unite to form a trunk,
the superior intercostal vein
 The right superior intercostal vein is the
final tributary of the azygos vein, before it
enters the SVC
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 Most posterior intercostal veins (4th -11th ) end in the
azygos/hemiazygos venous system, which conveys
venous blood to the SVC
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Diaphragm
 Dome-shaped musculotendinous partition
between thoracic and abdominal cavities
 Principal muscle of respiration
 Composed of two portions:
 Muscular (peripheral part)
 Aponeurotic (central part)

 Muscular part
 Fibers converge radially to central tendon
 3 parts based on origin
 Sternal – back of xiphoid process
 Costal – inner surface of lower six costal cartilage
 Vertebral – lumbar vertebrae by two crura
 Right – superior 3
 Left – superior 2
 Crura are united superiorly at T12 by narrow arch
called median arcuate ligament
 Central tendon
 Aponeurotic tendon formed by fibers of different
direction
 Has three lobes (right, left & median)
 Relations of the lobes
 Left – left pleura
 Right – right pleura
 Median – pericardium

Major openings
• Aortic – T12 median plane, transmits
descending aorta, thoracic duct, azygos vein
• Esophageal – T10 left of the median plane,
transmits esophagus, vagi (anterior &
posterior), esophageal branch of left gastric
artery
• Vena caval – T8 right of the median plane with
in the central tendon, transmits IVC, branch
of right phrenic, lymph vessels from liver

• Nerve supply
– phrenic (motor and sensory)
– lower six intercostal and subcostal for peripheral part
(sensory)
• Blood supply
–Arteries
• Superior surface
– superior phrenic (thoracic aorta)
– musculophrenic and pericardiacophrenic (internal
thoracic artery)
• Inferior surface: inferior phrenic
–Veins: same
• Lymphatic drainage
– Thoracic surface to phrenic nodes
– Abdominal surface to lateral aortic nodes
– The two surfaces communicate freely

Other structures passing through diaphragm
• Superior epigastric vessels – between sternal &
costal origins
• Phrenic nerve – pierce at 7 or 8 costal cartilage
• Lower five intercostal nerves - between two
slips of costal origin
• Subcostal nerves and vessels - behind lateral
arcuate ligament
• Quadratus lumborum - behind lateral arcuate
ligament
• Sympathetic trunk - behind medial arcuate
ligament
• Psoas major – behind medial arcuate ligament
• Splanchnic nerves – pierce the corresponding
crus of diaphragm
• Hemiazygos vein - pierce the left crus of
diaphragm

Diaphragmatic Herniae
 Acquired herniae may occur in middle-aged people
with weak musculature around the esophageal
opening in the diaphragm
 These herniae may be either sliding or
paraesophageal
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Sliding VS parasternal esophageal
hernia
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Respiratory movements
 Breathing or pulmonary ventilation consists of two
phases
 Inspiration: the period when air flows into the lungs
 Expiration: the period when gases exit the lungs
 Lungs expand during inspiration and retract during
expiration
 One of the principal functions of the thoracic wall and
the diaphragm is to alter the volume of the thorax and
thereby move air in and out of the lungs
 These movements are governed by:
 Movements of thoracic wall to increase the volume of
thoracic cavity
 Elastic recoil of lungs and thoracic wall

 During breathing, the dimensions of the thorax change
in the vertical, lateral, and anteroposterior directions
 Elevation and depression of the diaphragm
significantly alter the vertical dimensions of the
thorax
 Depression results when the muscle fibers of the
diaphragm contract
 Elevation occurs when the diaphragm relaxes
 Changes in the anteroposterior and lateral dimensions
result from elevation and depression of the ribs
 Any muscles attaching to the ribs can potentially move
one rib relative to another and therefore act as
accessory respiratory muscles
 Muscles in the neck and the abdomen can fix or alter the
positions of upper and lower ribs
155
Principles of movement
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 Each rib is considered as a lever, with the fulcrum
lies lateral to tubercle
 Because the anterior ends of the ribs are inferior to
the posterior ends, when the ribs are elevated, they
move the sternum upward and forward. When the
ribs are depressed, the sternum moves downward
and backward. This 'pump handle' type of
movement changes the dimensions of the thorax in
the anteroposterior direction
 As well as the anterior ends of the ribs being lower
than the posterior ends, the middles of the shafts
tend to be lower than the two ends. When the
shafts are elevated, the middles of the shafts move
laterally. This 'bucket handle' movement increases
the lateral dimensions of the thorax

Pump handle movement of ribs and sternum

Bucket handle movement of ribs

Inspiration
 During inspiration the lungs increase in volume
by enlarging in all dimensions
 Inspiration lowers the air pressure within the
lungs
 Air flows from areas of high pressure to areas
of low pressure to equalize the pressure
within the lung to that outside the lung
 During normal quiet inspiration, the diaphragm
and external intercostal muscles produce the
movement

Inspiration: action of diaphragm
 When the dome
shaped diaphragm
contracts, it
moves inferiorly
and flattens
 As a result the
vertical
dimension of the
thoracic cavity
increases
160
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Inspiration: action of intercostals
 The external
intercostal muscles
contract to raise the
ribs
 Because the ribs
normally extend
anterioinferiorly
from the vertebral
column, lifting them
enlarges both the
lateral and anterior
dimensions
161
by Abera N (MSC)

Deep inspiration
 During deep or forced inspiration, additional
muscles contract and further increase thoracic
volume
 The rib cage is elevated by the scaleni and
sternocleidomastoid muscles
 Scapulae are elevated and fixed by trapezius,
levator scapulae, rhomboids so that serratus
anterior and pectoralis minor act on ribs
163
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Expiration
 As the respiratory muscles
relax, the rib cage drops
under the force of gravity
and the relaxing diaphragm
moves superiorly
 At the same time, the
many elastic fibers within
the lungs recoil
 The result is the volume
of the thorax and lungs
decrease simultaneously,
which pushes air from the
lungs
164
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Forced expiration
 Quiet expiration in healthy people is a passive
process
 Forced expiration is an active process
produced by contraction of muscles in the
abdominal wall, primarily the oblique and
transverse abdominis muscles
 These contractions
 Increase the intrabdominal pressure which forces
the diaphragm superiorly
 Sharply depresses the rib cage
 Thus decreases thoracic volume
 The internal intercostal muscles, quadratus
lumborum and latissimus dorsi also help to
depress the rib cage

Components of the Respiratory System
1. Nose
2. Pharynx (throat)
3. Larynx (voice box)
4. Trachea (wind pipe)
5. Bronchi, and
6. Lungs
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• Structurally the respiratory system consist of two
parts:
1. Upper respiratory system:- consists of nose, pharynx and
associated structures
2. Lower respiratory system:– consists of larynx, trachea, bronchi,
and lungs
• Functionally the respiratory system consists of two
portions:
1. Conducting portion :- mouth/nose, pharynx, larynx, trachea,
bronchus, bronchioles (up to the terminal bronchioles)
- are transporting (conducting) gases to and from the alveoli
- filter, warm, and moisten inspired air
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Gross anatomy of the respiratory system

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Structural divisions of the respiratory system

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Functional divisions of the respiratory system

2. Respiratory portion:
• respiratory bronchioles,
• alveolar ducts,
• alveolar sacs, and
• alveoli
- consists of tissues within
the lungs
- is the main site of gas
exchange between air and
blood
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The conducting passages
• Air is conducted through the oral and nasal cavities to the
pharynx and then through the larynx to the trachea and
bronchial tree.
• These structures deliver warmed and humidified air to the
respiratory division in the lungs.
• The passageways are lined with various types of epithelia to
prepare the air properly for utilization.
• The majority of conducting passages are held permanently
open by muscle on a bony or cartilaginous framework.
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THE NOSE
 The part of the respiratory tract superior to the hard
palate.
 contains the peripheral organ of smell.
 It includes: the external nose and nasal cavity.
 The functions of the nose are;
olfaction (smelling)
 respiration (breathing)
filtration of dust, humidification of inspired air,
reception and elimination of secretions from the
paranasal sinuses and nasolacrimal ducts.
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External Nose
 has two elliptical orifices called the nostrils.
 The lateral margin, the ala nasi, is rounded and mobile.
Skeleton of the External Nose
 composed of bone and hyaline cartilage
 The bony part of the nose consists of:
 the nasal bones
 frontal processes of the maxillae
 the nasal part of the frontal bone
 its nasal spine, and the bony parts of the nasal septum.
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 The cartilaginous part of the nose;
 consists of five main cartilages:
 two lateral cartilages
 two alar cartilages
 one septal cartilage.
 The U-shaped alar cartilages are free and movable
 they dilate or constrict the nares when the muscles
acting on the nose contract.
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Nasal cavities
 Location
 Irregular space between the orbit, above the mouth
and below the middle part of anterior cranial fossa
 Wider below than above
 Widest and vertically deepest in its central region
 Extends from nostrils to the posterior nasal apertures
(choanae), leading to the nasopharynx
 Divided into the right and left nasal cavities by
osteocartilaginous septum
 The bony part reaches the posterior limit of the cavity
 Communicates with Paranasal sinuses
 Opens to nasopharynx through pair of oval openings named choanae
separated by posterior border of vomer

 Each nasal
cavity has
1. Roof
2. Floor
3. Medial wall
4. Lateral
wall
5. vestibule

Floor of nasal
cavity
 Wider than roof
 Formed by palatine
processes of the
maxilla and
horizontal plates
of the palatine
bone
 Separates the
nasal cavity from
the oral cavity

 Roof of nasal cavity
 Curved and narrow
 Anterior part: frontal and nasal bones
 Intermediate part: cribriform plate of ethmoid bone
 Posterior part: anterior and inferior aspects of the body of the
sphenoid bone

Regions
 Each nasal cavity consists of three general regions-
 Nasal vestibule
 is a small dilated space just internal to the naris that is lined by
skin and contains hair follicles
 Respiratory region
 is the largest part of the nasal cavity, has a rich neurovascular
supply, and is lined by respiratory epithelium composed mainly
of ciliated and mucous cells
 Olfactory region is small, is at the apex of each nasal
cavity, is lined by olfactory epithelium, and contains
the olfactory receptors

 Olfactory area
Contain peripheral organ of smell
Superior 1/3 of nasal mucosa; roof,
medial and lateral wall up to superior
concha
Contain olfactory cells; axons
constitute olfactory nerve

 Medial wall (Nasal septum)
 Osteocartilagenous partition between the two halves
 Bony part: formed by perpendicular plate of ethmoid
bone and vomer bone and the nasal crests of the
maxillary and palatine bones
 Cartilaginous part: formed by septal
cartilage and inferior nasal cartilage
 Cuticular part: lower anterior end formed by
fibroadipose tissue

185
Medial
wall
(Nasal
septum
)
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 Lateral wall
 Skeletal part
 Bony part - Nasal bone, maxilla and its frontal process, lacrimal bone,
ethmoid bone, inferior nasal concha, medial pterygoid and perpendicular plate
of palatine
 Cartilaginous part – upper nasal, lower nasal and ala
 Cuticular part – lower part formed by fibroadipose tissue
 Posses 3 shelf like processes; superior, middle and inferior nasal conchae and
their corresponding meatuses

 Features of the lateral wall of nasal cavity
 Conchae
 bony projections in the lateral wall of the nasal
cavity
 directed downwards and medially
 middle and superior conchae are processes of the
ethmoid while the inferior one is a separate bone

189
Lateral wall
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 Meatus
 Spheno-ethmoidal recess - space between the roof
of the nasal cavity and the superior concha; feature
opening of spenoidal sinus
 Space between conchae and lateral wall of the
nasal cavity
 Superior meatus – below superior concha; feature
opening of posterior ethmoidal sinus
 Middle meatus – under middle conchae
 Presents round elevation called bulla ethmoidalis produced
by the middle ethmoidal air sinus
 There is a semilunar groove called hiatus semilunaris below
and in front of the bulla ethmoidalis
 Inferior meatus – below inferior conchae;
nasolacrimal duct opens into it

194
Spheno-ethmoidal recess
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 Foramina opening in the nasal cavity
1. Nasolacrimal duct - to the inferior meatus
2. Incisive foramina - in the anterior floor of the
nose which transmits the sphenopalatine and
terminal parts of the greater palatine vessels
3. Olfactory foramina - in the cribriform plate of
the ethmoid - transmit olfactory nerves
4. Sphenopalatine foramen - connects the posterior
part of the superior meatus with pterygopalatine
fossa. It transmits sphenopalatine vessels and
nasopalatine and superior nasal nerves

Fibers of the olfactory nerve [I]
Anterior ethmoidal nerve,
A branch of the ophthalmic nerve
[V1],
pterygopalatine fossa
The nasopalatine nerve from
the nasal cavity into the oral
cavity;
The terminal end of the
greater palatine artery from
the oral cavity into the nasal
cavity
Gateways
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 Lateral wall of the nasal cavity
 Openings of the paranasal sinuses
 Frontal sinus drains into the superior aspect of the
hiatus semilunaris
 Anterior and middle ethmoidal air sinuses drain
through openings of the ethmoidal bulla on
superoposterior aspect of the hiatus semilunaris
 Posterior ethmoidal sinus – in to the superior meatus
 Maxillary air sinus has its ostium directly inferior to
the ethmoid bulla within the hiatus semilunaris
 Sphenoid sinus - sphenoethmoidal recess

Nerves of the nasal cavity
 Nerves of smell
 Olfactory nerve [CN I]
 Composed of axons from receptors in the olfactory
epithelium at the top of each nasal cavity
 Bundles of these axons (12 – 20) pass superiorly
through perforations in the cribriform plate to
synapse with neurons in the olfactory bulb of the brain
 General sensory
 Derived from ophthalmic and maxillary divisions of CN
V which is associated with the pterygopalatine ganglion

 Nasal septum
 Anterior superior part – septal branch of anterior
ethmoidal (V1)
 Posterior inferior part – nasopalatine (V2)
 Vestibule of the nose
 terminal branches of the infraorbital nerve (V2)
 Lateral wall
 Anterior superior quadrant - anterior ethmoidal (V1)
 Anterior inferior quadrant – internal nasal branch of
infraorbital (V2) and small branch from anterior
superior alveolar (V2)
 Posterior superior part - posterior superior lateral
nasal branch of pterygopalatine ganglion (V2)
 Posterior inferior part - posterior inferior lateral
nasal branch of greater palatine (V2)

 Parasympathetic innervation
 Secretomotor innervation of mucous glands in the nasal cavities
and paranasal sinuses is by preganglionic parasympathetic fibers
carried in the greater petrosal branch of the facial nerve
 These fibers enter the pterygopalatine fossa and synapse in the
pterygopalatine ganglion
 Postganglionic parasympathetic fibers then join branches of the
maxillary nerve [V2] to leave the fossa and ultimately reach
target glands

 Sympathetic innervation
 Sympathetic innervation, mainly involved with regulating blood flow in the nasal
mucosa,
 is from the spinal cord level T1
 Preganglionic sympathetic fibers enter the sympathetic trunk and ascend to
synapse in the superior cervical ganglion
 Postganglionic sympathetic fibers pass onto the internal carotid artery, enter
the cranial cavity, and then leave the internal carotid artery to form the deep
petrosal nerve, which joins the greater petrosal nerve of the facial nerve and
enters the pterygopalatine fossa
 Like the parasympathetic fibers, the sympathetic fibers follow branches of the
maxillary nerve [V2] into the nasal cavity

Blood supply of the nasal cavity
 Arteries
 Arteries that supply the nasal cavity include vessels that
originate from both the internal and external carotid
arteries:
 vessels that originate from branches of the external carotid
artery include the sphenopalatine, greater palatine, superior labial,
and lateral nasal arteries
 vessels that originate from branches of the internal carotid
artery are the anterior and posterior ethmoidal arteries
 Nasal septum
 Anterosuperior- anterior and posterior ethmoidal and
superior labial branch of maxillary
 Posteroinferior – sphenopalatine and greater palatine;
anastomose

 Lateral wall
 Anterosuperior – anterior and posterior ethmoidal
 Anteroinferior – facial and greater palatine
 Posterosuperior - sphenopalatine
 Posteroinferior – sphenopalatine

 Applied anatomy
 On the anterior part of the nasal septum is an area rich
in capillaries (Kiesselbach area) where all five arteries
supplying the septum anastomose
 This area is often where profuse bleeding from the nose
occurs - nose bleed (epistaxis) resulting from rapture of
arteries particularly at site of anastomoses
 Anterior ethmoidal artery (from the ophthalmic artery).
 Posterior ethmoidal artery (from the ophthalmic artery).
 Sphenopalatine artery (from the maxillary artery).
 Greater palatine artery (from the maxillary artery).
 Septal branch of the superior labial artery (from the facial
artery)
by Abera N (MSC)
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 Veins
 The venous drainage of the nose parallels the arterial
supply and forms a network, submucosal plexus
overlying the inferior and middle concha
 The tissue overlying the concha humidifies and warms
the inspired air in the upper respiratory passage
 Nasal septum – veins from plexus to facial (anterior
part) and pterygoid plexus (posterior part)
 Lateral wall – plexus to facial (anterior part),
pharyngeal plexus (posterior part) and pterygoid plexus
(middle part)

Lymphatic drainage of the nasal cavity
 Anterior half – submandibular lymph nodes
 Posterior half - to retropharyngeal or deep
cervical lymph node

Rhinitis
 inflammatory disorder of the mucous membrane of the nose.
 characterized by a watery discharge from the nose often
associated with congestion.
 Swelling of the mucosa occurs readily because of its
vascularity.
by Abera N (MSC)
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Infections of the nasal cavities may spread to
the
 Anterior cranial fossa through the cribriform plate
 Nasopharynx and retropharyngeal soft tissues
 Middle ear through pharyngotympanic tube
 Lacrimal apparatus and conjunctiva
 Paranasal sinuses
by Abera N (MSC)
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Paranasal sinuses
Are air filled cavities in
the bones of the skull
around nasal cavity.
 Function;
 Make skull lighter
 Increase the resonance of
sound
4 types of sinuses
 Frontal
 Ethmoidal
 Sphenoidal
 Maxillary
by Abera N (MSC)
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Paranasal Sinuses
by Abera N (MSC)
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 Frontal Sinuses
 are between the outer and the inner tables of the frontal
bone,
 Located posterior to the superciliary arches and the root
of the nose.
 usually detectable in children by 7 years of age.
 Each sinus drains through a frontonasal duct into the
ethmoidal infundibulum-semilunar hiatus of the
middle nasal meatus.
 innervated by branches of the supraorbital nerves (CN
V1).
220

Ethmoidal air sinues; Ethmoidal Cells
• small invaginations of the mucous membrane of the
middle and superior nasal meatus into the ethmoid
bone between the nasal cavity and the orbit.
• The anterior ethmoidal cells drain directly or
indirectly into the middle nasal meatus through the
ethmoidal infundibulum.
• The middle ethmoidal cells (bullar cells) open
directly into the middle meatus.
• The posterior ethmoidal cells open directly into the
superior meatus.
• The ethmoidal cells are supplied by the anterior and
posterior ethmoidal branches of the nasociliary nerves
(CN V1)
by Abera N (MSC)
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Infection of the Ethmoidal Cells
 If nasal drainage is blocked, infections of the ethmoidal
cells may break through the fragile medial wall of the orbit.
 may cause blindness because some posterior ethmoidal cells
lie close to the optic canal, passage to the optic nerve and
ophthalmic aa.
 could also affect the dural nerve sheath of the optic nerve,
causing optic neuritis.
by Abera N (MSC)
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Sphenoidal Sinuses
 located in the body of the sphenoid and may extend into
the wings of this bone.
 They are unevenly divided and separated by a bony
septum
 Because of this extensive pneumatization (formation of
air cells or sinuses), the body of the sphenoid is fragile
 Only thin plates of bone separate the sinuses from
several important structures:
 the optic nerves and optic chiasm
 the pituitary gland
 the internal carotid arteries
 and the cavernous sinuses.
by Abera N (MSC)
224

The sphenoidal sinuses are derived from a
posterior ethmoidal cell that begins to invade the
sphenoid at approximately 2 years of age
several posterior ethmoidal cells invade the
sphenoid, giving rise to multiple sphenoidal
sinuses that open separately into the
sphenoethmoidal recess
The posterior ethmoidal arteries and posterior
ethmoidal nerve supply the sphenoidal sinuses
by Abera N (MSC)
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Maxillary Sinuses
 The maxillary sinuses are the largest of the paranasal
sinuses
 They occupy the bodies of the maxillae and
communicate with the middle nasal meatus
 The apex : extends toward the zygomatic bone
 The base: forms the inferior part of the lateral wall of the
nasal cavity
 The roof is formed by the floor of the orbit
 The floor is formed by the alveolar part of the maxilla
 The roots of the maxillary teeth, particularly first two molars,
produce conical elevations in floor of the sinus.
by Abera N (MSC)
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The arterial supply of the maxillary sinus is mainly from
superior alveolar branches of the maxillary artery
branches of the descending and greater palatine arteries
supply the floor of the sinus
Innervation of the maxillary sinus
from the anterior, middle, and posterior superior alveolar
nerves, which are branches of the maxillary nerve
by Abera N (MSC)
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Infection of the Maxillary Sinuses
 the most commonly infected sinuses, why?
 Because the ostia of the right and left sinuses lie on the
medial sides, when lying on one's side only the upper sinus
drains
 A cold or allergy involving both sinuses can result in nights
of rolling from side-to-side in an attempt to keep the
sinuses drained
 A maxillary sinus can be cannulated and drained by passing
a cannula from the nares through the maxillary ostium into
the sinus
by Abera N (MSC)
229

Applied anatomy
 Infection may spread from nasal cavity to sinuses and produce
sinusitis, swelling of mucosa may block opening to nasal cavity
 Maxillary sinus is commonly involved because its aperture is
located superior to floor of sinus thus drainage is poor.
 It is better drained when one is lying on the side opposite
infected sinus

Relationship of the Teeth to the Maxillary Sinus
 The close proximity of the three maxillary molar teeth
to the floor of the maxillary sinus poses serous problems
 During removal of a molar tooth, fracture and piece of
root may driven superiorly into the maxillary sinus
 communication may be created between the oral cavity
and the maxillary sinus as a result, an infection occur
 Because the superior alveolar nerves supply both the
maxillary teeth and the mucous membrane of the
maxillary sinuses,
inflammation of the mucosa of the sinus is frequently
accompanied by a sensation of toothache in the molar
teeth
by Abera N (MSC)
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Pharynx: introdduction
 Funnel shaped fibromuscular tube
found behind nasal, oral and laryngeal
cavities
 Extends from the base of skull to
inferior border of cricoid cartilage
(C6) = 12 cm long
 Lies between the bodies of the
vertebrae and the larynx between
C1-6
 Becomes continuous with the
esophagus at C6

Pharynx cont…
 Conducts food and air
 The cavity above the inlet
of larynx is wide and
always open
 The cavity below the inlet
of the larynx is narrow,
the anterior & posterior
parts are in contact
except during food passes

 Boundaries and relation
 Superior – body of sphenoid and basilar part of
occipital bone
 Inferior – continues with esophagus
 Posterior – prevertebral fascia
 Anterior – communicate with nasal cavity, oral cavity
and larynx
 Lateral – attached to medial pterygoid plate,
pterygomandibular raphe, mandible, tongue, hyoid,
thyroid and cricoid cartilage
 Parts: nasal (nasopharynx), oral (oropharynx) and
laryngeal (laryngopharynx)

Line of attachment of the pharynx to the base
of the skull

237 Attachments of the lateral pharyngeal wall
by Abera N (MSC)

 Openings in the pharynx
 Anterior
 Two posterior nasal openings
 Oropharyngeal isthmus
 Inlet of larynx
 Lateral – openings of the
auditory tube
 Inferiorly – into esophagus
 Walls of the pharynx
 Composed of (inside out)
1. Mucus membrane
2. Submucosa
3. Pharyngobasilar fascia
4. Muscles

 Pharyngobasilar fascia
 Covers the internal surface of
the constrictor muscles
 Connects pharynx with the base
of the skull and fill the gap
between the superior constrictor
and skull
 Together with the
buccopharyngeal fascia fill the
gaps in the muscular wall
 Buccopharyngeal fascia
 covers the external surface of
the buccinator muscle and the
superior constrictor muscle
 contains: pharyngeal venous
plexus and pharyngeal plexus of
nerves

 Pharyngeal plexus of
veins
 lies deep to this fascia,
draining the pharynx,
soft palate and the
pharyngeal tonsil
 communicates with the
pterygoid plexus of veins
and drains into the
internal jugular vein
 these veins have no valves
and infection from the
pharynx, palate and
tonsils may spread into
the meningeal venous
plexus

 Pharyngeal nervous
plexus
 Formed by branches from
CN IX, X and superior
cervical ganglion
 Motor branches – CN X
(cranial root of accessory
nerve)
 supply all muscles of pharynx
and palate except
stylopharyngeus (CN IX) and
tensor palati (CN V3)
 inferior constrictor receive
additional fibers from
external and recurrent
laryngeal nerves

by Abera N (MSC)
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Sensory branches
nasopharynx -
maxillary nerve (CN
V2)
oropharynx - CN IX
laryngopharynx -
vagus
Parasympathetic –
greater petrosal nerve

 Muscular layer
 Inner longitudinal and outer circular skeletal muscles
 6 paired skeletal muscles
– Three pairs of circular muscles (external muscles): superior,
middle and inferior constrictor muscles
– Three pairs of longitudinal (internal muscles):
palatopharyngeus, stylopharyngeus & salpingophayngeus
 External muscles
 Originate anteriorly and pass posteriorly and meet in
midline fibrous raphe
 Inferior overlap middle and middle overlap superior
 Constrict pharynx during swallowing

 Superior constrictor
muscle
 Lies behind the nasal and
oral cavities and continuous
with the plane of the
buccinator
 Origin – pterygoid hamulus,
pterygomandibular raphé,
posterior end of mylohyoid
line of mandible & the side
of the tongue
 Insertion – median raphé of
pharynx and pharyngeal
tubercle

 Middle constrictor
muscle
 Lies behind the tongue
and larynx
 It is truly a constrictor
and plays a major role in
swallowing
 Origin - stylohyoid
ligament, greater and
lesser horns of hyoid
bone
 Insertion - median
raphé of pharynx

by Abera N (MSC)
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Inferior
constrictor muscle
Origin – oblique line of
thyroid cartilage and the
sides of cricoid cartilage
Insertion – median raphé
of pharynx
The most inferior aspect
is the cricopharyngeus
which is the sphincter
between the pharynx and
the esophagus

 Innervation of constrictor muscles
 Superior and middle constrictor muscles are innervated
by the pharyngeal branches of the vagus nerve
 Inferior constrictor muscle and the cricopharyngeus
are innervated by recurrent branches of the vagus
nerve
 The three muscles overlap each other and form
three gaps which allow entrance of structures to
pharynx
 The interval between the superior constrictor and base
of the skull: allows for
 Levator veli palatini
 Auditory tube
 Ascending palatine artery

 The interval between superior
and middle constrictor
 Stylopharyngeus
 Cranial nerve IX
 Stylohyoid ligament
 The interval between middle &
inferior constrictors covered
by thyrohyoid membrane
transmits
 Internal laryngeal nerve
 Superior laryngeal vessels
 Between the inferior
constrictor and esophagus
 Inferior laryngeal vessels
 Recurrent laryngeal nerve

 Internal muscles of the
pharynx
 Elevates larynx and pharynx during
swallowing
 Stylopharyngeus
 Origin - styloid process of temporal
bone
 Insertion - posterior & superior
border of the thyroid cartilage
 Course - descends between
external & internal carotid arteries
and enters the pharyngeal cavity
with CN IX between the superior
and middle constrictor muscles
 Nerve supply - CN IX

 Palatopharyngeus
 Origin - hard palate and palatine
aponeurosis
 Insertion – posterior border of
lamina of thyroid cartilage and
sides of pharynx
 Nerve supply – pharyngeal plexus
 The overlying mucosa forms the
palatopharyngeal arch, posterior
to the palatine tonsil
 Salpingophayngeus
 Origin – cartilaginous part of
auditory tube
 Insertion – blend with
palatopharyngeus
 Nerve supply - pharyngeal plexus

 Cavity of the pharynx
 3 parts - Nasopharynx, Oropharynx & Laryngopharynx
 Nasopharynx
 Behind nose and above lower border of soft palate
 Respiratory
 Walls
 Roof – sphenoid & occipital bone, mucus membrane, submucosa
(contain pharyngeal tonsil)
 Floor – soft palate
 Anterior wall – two posterior openings of the nasal cavity
 Posterior wall - anterior part of atlas lined with mucus
membrane

 Lateral wall – presents
 Pharyngeal openings of auditory tube – behind
inferior nasal concha
 Tubal elevation - posterior to the auditory
openings
 Salpingopharyngeus fold – inferior to tubal
elevation due to the muscle
 Pharyngeal recess – depression behind tubal
elevation
 Tubal tonsil – lymphoid tissue in the submucosa
behind the openings of the auditory tube
 Inferiorly – Nasopharynx communicate with oropharynx at
nasopharyngeal isthmus

 Oropharynx
 Behind oral cavity, extends from
soft palate to the upper border of
epiglottis
 Walls
 Anterior - communicate with oral cavity
through oropharyngeal isthmus (isthmus
of fauces)
 Laterally bounded by two arches –
palatoglossal & palatopharyngeal;
between them triangular fossa for
palatine tonsil
 Inferiorly pharyngeal part of tongue –
contain lingual tonsil
 Posterior wall – body of axis and upper
part of C3 lined with mucus membrane

 Palatine tonsil
 Almond shape
 Medial surface has crypts and lateral surface covered
by fascia
 Applied anatomy
 Adenoids – enlargement of pharyngeal tonsils
 Obstruct nasal respiration
 Infection may spread to middle ear through auditory tube
 Tonsillectomy – removal of tonsil
 Bleeding may arise from tonsilar artery and external palatine
vein
 Nerves vulnerable – CN IX & lingual nerve

 Laryngopharynx
 Posterior to the
larynx, from superior
border of epiglottis
to inferior border of
cricoid
 Walls
 Anterior
 Communicate with
larynx through inlet of
larynx; bounded by
epiglottis,
aryepiglottic fold &
inter arytenoid folds
 Mucus membrane
covering posterior
surface of larynx

by Abera N (MSC)
270
Posterior –
related to C4 -
C6 vertebrae
Lateral – mucus
membrane
covering the
thyroid cartilage
and thyrohyoid
membrane,
presents
piriform recess

 Piriform resses (fossa)
 Groove on the side of inlet
of larynx
 Bounded by aryepiglottic
fold medially & thyroid
cartilage and thyrohyoid
membrane laterally
 Site for arrest of foreign
body and produce cough
 The mucosa is supplied by
internal laryngeal nerve
 Branches of internal and
recurrent laryngeal
nerves lie in the recess

 Arteries
 Ascending
pharyngeal
 Ascending palatine
 Tonsilar branch of
facial artery
 Branches from
lingual & maxillary
 Veins – end in
pharyngeal plexus
that ends in the
internal jugular
vein and facial vein

by Abera N (MSC)
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The larynx

Larynx
 It is a hollow musculoligamentous
structure with a cartilaginous
framework
 Its cavity is continuous
 inferiorly with the trachea,
 superiorly opens into the pharynx
immediately posterior and slightly
inferior to the tongue and the
oropharyngeal isthmus
 Functions
 Air passage to trachea
 Sound production
 Acts as a valve for preventing
swallowed food from entering
the lower respiratory tract

 Position
 Extension: At midline of neck
from root of tongue to trachea
 Posteriorly: laryngopharynx
opposite C3 to C6
 Superiorly: continuous with
laryngopharynx through the inlet
of larynx
 Inferiorly: continuous with
trachea
 Length: About 5 cm in adult man
but slightly shorter in female
 Attachments: Suspended from
the hyoid bone above and
attached to the trachea below
by membranes and ligaments

by Abera N (MSC)
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 It is highly mobile in the neck
and can be moved up and down
and forward and backward by
the action of extrinsic muscles
that attach either to the larynx
itself or to the hyoid bone
 During swallowing, the upward
and forward movements of the
larynx facilitate
 closing the laryngeal inlet and
 opening the esophagus

 Structure: composed of
 9 cartilages joined by
ligaments and
membranes
 Three large
unpaired cartilages
1. Thyroid
2. cricoid
3. epiglottis
 Three pairs of
smaller cartilages –
1. arytenoid,
2. corniculate &
3. cuneiforms
 Muscles – intrinsic

Thyroid cartilage
 Have two quadrilateral plates called laminae,
 widely separated posteriorly, but converge and join
anteriorly
 Placed obliquely; whe
 inferior 2/3 is fused anteriorly in the midline
 The angle of fusion is more acute in the male (90°) than in
women (120°)and forms the laryngeal prominence (Adam's
apple) after puberty
 Has two notches in the mid line anteriorly
 superior thyroid notch: v shaped palpable land mark
 inferior thyroid notch: less distinct along the base of the thyroid cartilage
284
•Both the superior
thyroid notch and the
laryngeal prominence
are palpable landmarks
in the neck
by Abera N (MSC)

 Each lamina has two projection from posterior border
 Superior horn is connected to greater horn of hyoid by lateral
thyrohyoid ligament
 Inferior horn articulate with cricoid cartilage
 The upper border is attached to the hyoid bone by the thyrohyoid membrane
 Lateral surface is marked by a ridge - oblique line that
 curves Anteriorly from the base of the superior horn to a little
short of midway along the inferior margin of the lamina
 the ends of the oblique line are expanded to form superior and inferior thyroid
tubercles
 Is attachment for sternothyroid, thyrohyoid and inferior
constrictor muscles

 Cricoid cartilage
 Ring shaped; completely
encircles the airway
 Have broad quadrilateral
lamina posteriorly and
narrow arch anteriorly
 Its anterior arch is
attached superiorly to
the thyroid cartilage by
the cricothyroid
membrane
 The thickened midline
portion of this membrane
is the median
cricothyroid ligament

Lamina projects upwards and
articulates with arytenoid
Has two articular facets on
each side for articulation
with other laryngeal
cartilages
facet on superolateral
surface of the lamina -
articulates with the base
of arytenoid cartilage
facet on lateral surface of
the lamina near its base -
for articulation with the
medial surface of the
inferior horn of the
thyroid cartilage

 Epiglottis
 Leaf-shaped, broad flat plate of fibrocartilage at
anterior wall of upper part of larynx
 Upper end – broad, free, projects behind the tongue
and hyoid bone, above and in front of the inlet of
larynx
 Lower end – pointed, attached above the angle of
fusion of the thyroid cartilage by the thyroepiglottic
ligament
 Attached to
 tongue by median glossoepiglottic fold
 Pharynx by lateral glossoepiglottic fold
 hyoid bone by hyoepiglottic ligament
 The inferior half of the posterior surface of the
epiglottis is raised slightly to form an epiglottic
tubercle

 Function of epiglottis
 Respiratory: remain in resting position during inhalation letting the
air enter the lungs
 Digestive: the extrinsic muscles atached with larynx move it up so
it can lay flat over the laryngeal opening making the food pass
safely through esophagus
 Malfunction or failure to close properly make you cough
and choke every time you swallow

 Arytenoid cartilages
 Three sided pyramid with a base
and apex
 On upper border of lamina of
cricoid
 Apex – curved posteromedially and
articulate with corniculate
cartilage
 Base – concave, articulate with
cricoid lamina through synovial
joint called crico-arytenoid
 Surfaces
 medial surface - faces each other
 anterolateral surface - has two
depressions, separated by a ridge, for
muscle (vocalis) and ligament (vestibular
ligament) attachment
 Posterior surface

Has two processes
vocal process -
anterior & attach
to the vocal
ligament
muscular process -
lateral & serves as
attachment points
for muscles of the
larynx
Control the opening
between the vocal
cords, the rima
glottidis

 Corniculate cartilage
 Small conical nodules of
fibrocartilage whose base
articulate with the apex of
arytenoid cartilage in the
posterior part of
aryepiglottic fold
 Their apices project
posteromedially towards
each other
 Cuneiform cartilage
 Rod shaped, found in the
aryepiglottic fold, anterior
to the arytenoid cartilage

Ligaments and membranes cont..
Extrinsic ligaments
 Thyrohyoid membrane & ligament
 Connect upper border of thyroid cartilage to body, greater & lesser horn of
hyoid
 Midline thickening – median thyrohyoid ligament
 Posterior border thickening – lateral thyrohyoid ligament
 Occasionally, there is a small cartilage (triticeal cartilage) in each lateral
thyrohyoid ligament
 Outer surface covered with thyrohyoid muscle
 An aperture in the lateral part of the thyrohyoid membrane on each side is for
the superior laryngeal arteries, nerves, and lymphatics

 Hyoepiglottic ligament
 Connects the anterior
surface of the epiglottis
to the back of hyoid
 Median & lateral
glosso-epiglottic folds
 Connects the anterior
surface of the epiglottis
to the dorum the tongue
 Crico-tracheal
ligament
 Connects first ring of
trachea to cricoid

Intrinsic ligaments
 Fibro-elastic membrane of
larynx
 Links together the
laryngeal cartilages and
completes the
architectural framework
of the laryngeal cavity
 Composed of two parts-a
lower cricothyroid
ligament and an upper
quadrangular membrane

by Abera N (MSC)
302
Cricothyroid ligament
 Triangular in shape
Attached to the arch of
cricoid cartilage and
extends superiorly to end
in a free upper margin
within the space enclosed
by the thyroid cartilage
On each side, this upper
free margin attaches:
anteriorly to the
thyroid cartilage
posteriorly to the vocal
processes of the
arytenoid cartilages

 The free margin between these two points of attachment is
thickened to form the vocal ligament, which is under the
vocal fold (true 'vocal cord') of the larynx
 The cricothyroid ligament is also thickened anteriorly in the
midline to form a distinct median cricothyroid ligament,
which spans the distance between the arch of cricoid
cartilage and the inferior thyroid notch and adjacent deep
surface of the thyroid cartilage up to the attachment of the
vocal ligaments
 Outer surface covered with cricothyroid muscle
 Inner surface covered with mucous membrane
 Soft spot inferior to thyroid cartilage - air way is closest to
skin and most accessible
 In emergency situations, when the airway is blocked above the
level of the vocal folds, the median cricothyroid ligament can be
perforated to establish an airway
 Except for small vessels and the occasional presence of a
pyramidal lobe of the thyroid gland, normally there are few
structures between the median cricothyroid ligament and skin

 conus elasticus, Vocal
ligament, & vocal fold
 Conus elasticus
 triangular ligament connecting
cricoid, thyroid & arytenoid
cartilage
 Vocal ligaments
 attach between the vocal
processes of the arytenoid
cartilages and the thyroid
cartilage, behind its fusion
angle
 i.e. thickened upper border of
conus elasticus
 forms skeleton of vocal folds
 Vocal fold
 the upper border of conus
elasticus covered with the
mucous membrane

 Quadrangular membrane & vestibular ligaments
 The quadrangular membrane
 runs between the lateral margin of the epiglottis on each side
and the anterolateral surface of the arytenoid cartilage on the
same side
 Attachement: the corniculate cartilage, which articulates with
the apex of arytenoid cartilage
 has
 free upper margin and
 free lower margin
o The free lower margin is thickened to form the
vestibular ligament under the vestibular fold
(false 'vocal cord') of the larynx

 The vestibular ligament
 attachments
 posteriorly : the superior depression on the anterolateral
surface of the arytenoid cartilage
 anteriorly : the thyroid angle just superior to the attachment
of the vocal ligament
 Thin submucosal sheath extending from arytenoid
cartilage to the epiglottis
 Superior border forms aryepiglottic fold
 Inferior border forms vestibular fold
 On each side, the vestibular ligament of the
quadrangular membrane is separated from the vocal
ligament of the cricothyroid ligament below by a gap

309
The free lower
margin of
quadrangular
membrane is
thickened to form
the vestibular
ligament under the
vestibular fold
(false 'vocal cord')
of the larynx
by Abera N (MSC)

310
Thickening of
conus elasticus
Thickening of
quadrangular
membrane
by Abera N (MSC)

Joints of larynx
 Crico-arytenoid
 Synovial, between base of arytenoid and upper border of lamina of
cricoid cartilage
 Enable the arytenoid cartilages to slide away or towards each other
and to rotate so that the vocal processes pivot either towards or
away from the midline. These movements abduct and adduct the
vocal ligaments

 Crico-thyroid joint
 The joints between the inferior horns of the thyroid
cartilage and the the sides of cricoid cartilage at the
junction of its lamina and arch
 Synovial
 Each is surrounded by a capsule and is reinforced by
associated ligaments
 enable the thyroid cartilage to move forward and tilt
downwards on the cricoid cartilage
 Because the vocal ligaments pass between the posterior
aspect of the thyroid angle and the arytenoid
cartilages sit on the lamina of cricoid cartilage,
forward movement and downward rotation of the
thyroid cartilage on the cricoid cartilage effectively
lengthens and puts tension on the vocal ligaments

Cavity of the larynx
 The central cavity of the larynx is tubular in shape and is
lined by mucosa
 Its architectural support is provided by the fibro-elastic
membrane of larynx and by the laryngeal cartilages to
which it is attached
• Extend from inlet of larynx to inferior border of
cricoid
 The superior aperture of the cavity (laryngeal inlet)
 obliquely oriented, opens into the anterior aspect of
the pharynx just below and posterior to the tongue

 Borders
 anterior border - formed by mucosa covering the
superior margin of the epiglottis
 lateral borders - formed by mucosal folds
(aryepiglottic folds), which enclose the superior
margins of the quadrangular membranes and adjacent
soft tissues, and two tubercles on the more
posterolateral margin of the laryngeal inlet on each
side mark the positions of the underlying cuneiform
and corniculate cartilages
 posterior border - in the midline is formed by a
mucosal fold that forms a depression (interarytenoid
notch) between the two corniculate tubercles

 The inferior opening of the laryngeal cavity
 is continuous with the lumen of the trachea,
 is completely encircled by the cricoid cartilage,
 is horizontal in position unlike the laryngeal inlet,
which is oblique and points posterosuperiorly into the
pharynx

Division of laryngeal cavity
 Two pairs of mucosal folds, the vestibular and vocal
folds, which project medially from the lateral walls of
the laryngeal cavity, constrict it and divide it into three
major regions-
1. Vestibule –
 the upper chamber of the laryngeal cavity
 is between the laryngeal inlet and the vestibular folds
2. Middle part of the laryngeal cavity
 is very thin
 is between the vestibular folds above and the vocal folds
below
3. Infraglottic space –
 the most inferior chamber of the laryngeal cavity
 Is between the vocal folds and the inferior opening of the
larynx

Laryngeal ventricles and saccules
 Laryngeal ventricles
 expanded trough-shaped space (a laryngeal ventricle)
 Produced as the mucosa of the middle cavity bulges laterally
through the gap between the vestibular and vocal ligaments
 laryngeal saccule
 An elongate tubular extension of each laryngeal ventricle
 projects anterosuperiorly between the vestibular fold and thyroid
cartilage
 may reach as high as the top of the thyroid cartilage
 Within the walls of these laryngeal saccules are numerous mucous
glands
 Mucus secreted into the saccules lubricates the vocal folds.

Rima vestibuli and rima glottidis
 the rima vestibuli
 When viewed from above,it is a triangular-shaped opening
 Bounded by the two adjacent vestibular folds at the entrance to the middle
chamber of the laryngeal cavity
 The apex of the opening is anterior and its base is formed by
the posterior wall of the laryngeal cavity
 the rima glottidis
 Inferior to the vestibular folds
 the vocal folds (true vocal cords) and adjacent mucosa-covered parts of the
arytenoid cartilages form its lateral walls
 narrower triangular opening (between the two adjacent vocal folds)
 This opening separates the middle chamber above from the infraglottic
cavity below
 The base of this triangular opening is formed by the fold of mucosa
(interarytenoid fold) at the bottom of the interarytenoid notch
 Both the rima glottidis and the rima vestibuli can be opened and
closed by movement of the arytenoid cartilages and associated
fibro-elastic membranes

 Clinical correlates
 Laryngeal obstruction
 Lodging of aspirated food in rima glottidis
 Compression of abdomen (Heimlich maneuver) expel air from
lungs and dislodge the food

Muscles of larynx
Divided as extrinsic and intrinsic
 Extrinsic muscles – move larynx superiorly and
inferiorly during swallowing
 Infrahyoid muscles – depress hyoid and larynx
 Suprahyoid muscles – elevates hyoid and larynx
 Thyrohyoid – depress hyoid and elevate thyroid
cartilage

 Intrinsic muscles – move laryngeal parts and playing vital
role in breathing and phonation
 actions
 adjust tension in the vocal ligaments,
 open and close the rima glottidis (opening between vocal
folds and the arytenoid cartilage),
 control the inner dimensions of the vestibule,
 close the rima vestibuli, and
 facilitate closing of the laryngeal inlet

 They do this mainly by:
 acting on the cricothyroid and crico-arytenoid joints
 adjusting the distance between the epiglottis and
arytenoid cartilages
 pulling directly on the vocal ligaments
 forcing soft tissues associated with the quadrangular
membranes and vestibular ligaments toward the
midline

• The ntrinsic muscles Divided based on their action on inlet of
larynx
1. Muscles closing the inlet of the larynx
2. Abductor of vocal folds
3. Tensor of vocal cords
4. Adductors of vocal folds
5. Relaxer of vocal folds

Muscles closing the inlet of the larynx
 Transverse arytenoid muscle
 unpaired
 Origin: Lateral border of posterior surface of arytenoid cartilage
 Insertion: Lateral border of posterior surface of opposite
arytenoid cartilage
 Function: Adduction of arytenoid cartilages, vocal processes and
vocal cords
 Oblique arytenoid
 Superficial to transverse
 Origin: Posterior surface of muscular process of arytenoid
cartilage
 Insertion: Posterior surface of apex of adjacent arytenoid
cartilage; extends into aryepiglottic fold
 Function: Sphincter of the laryngeal inlet

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