ANATOMY LARYNX

1. Upper respiratory tract
larynx
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Lecture objectives
By the end of the lecture the students should be able
to:Describe cartilages and muscles of larynx
Describe blood and nerve supply of larynx
.
•
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3. LARYNX
• Is the upper ,
expanded part of
the windpipe
which is modified
for phonation
• Supported by a
number of
cartilages

5. • Complex organ of voice
production
• Composed of 9 cartilages
connected by membranes
and ligaments
• Contains the vocal folds
• Located anteriorly in the
neck
• Vertebral levels C3-C6
• Connects the inferior part of
the Oropharynx to the
trachea
• Lies anterior to the
Laryngopharnx
• Secondary function is to
guard the air passages

10. The only complete
ring circle in the
respiratory system

12. • Main divisions of the
Laryngeal Cavity
1- Laryngeal Vestibule
2- Laryngeal cavity
3- Infraglottic cavity

17. Muscle Origin Insertion Innervation Action
Cricothyroid Antero-lateral part
of cricoid cartilage
Inferior margin and
inferior horn of thyroid
cartilage
External
laryngeal nerve
Stretches and tenses
vocal ligament
Thyro-arytenoid Lower ½ of
posterior aspect of
angle of thyroid
laminae and
cricothyroid
ligament
Anterolateral arytenoid
surface
Inferior
laryngeal nerve
(terminal part of
recurrent
laryngeal nerve
from vagus)
Relaxes vocal
ligament
Posterior Crico-
arytenoid
Posterior surface
of lamina of cricoid
cartilage
Vocal process of
arytenoid cartilage
Abducts vocal folds
Lateral crico-
arytenoid
Arch of arytenoid
cartilage
Adducts vocal folds
Transverse &
Oblique arytenoids
One arytenoid
cartilage
Contra-lateral arytenoid
cartilage
Adducts arytenoid
cartilages
Vocalis Lateral surface of
vocal process of
arytenoid
cartilages
Ipsilateral vocal ligament Relaxes posterior vocal
ligament while
maintaining tension of
anterior part

18. • Superior
Laryngeal artery
Supplies the internal
surface of the
larynx
• Cricothyroid
artery
Supplies the
cricothyroid
muscle
• Inferior
Laryngeal artery
Supplies the mucous
membrane and
the muscles of the
inferior part of the
larynx

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Joints of the larynx
crico-arytenoid joints
Cricothyroid joints
Are synovial joints enable the thyroid cartilage to move
forward and tilt downward on the cricoid cartilage.
Forward movement and downward rotation of the thyroid
cartilage on the cricoid cartilage effectively lengthens and
puts tension on the vocal ligaments.
Crico-arytenoid joints
Are synovial joints that allow the arytenoid cartilages to slide
away or toward each other and to rotate so that the vocal
processes pivot either toward or away from the
midline. These movements abduct and adduct the vocal
ligaments
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• 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:
 the vestibule,
 a middle chamber (Laryngeal
ventricles and saccules),
 the infraglottic cavity.
Cavity of the larynx
Laryngeal cavity:
A. Posterolateral view.
B. Posterior view (cutaway).
C. Superior view through the laryngeal inlet.
D. Labeled photographs of the larynx, superior
view.
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Intrinsic
muscles of the larynx
Muscles that abduct the
vocal cords :
Posterior crico-arytenoid
muscles
Posterior view Superior view
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Muscles that adduct the vocal cords:
Lateral crico-arytenoid muscles & transverse arytenoid muscles.
Posterior view Side view
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• The rima vestibuli)
between the two adjacent
vestibular folds.
• The rima glottidis
between the two adjacent
vocal folds
Rima glottidis& Rima vestibuli
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Muscles that tense&
relax the vocal cords:
Cricothyroid muscles
(Tense the cords)
Relaxed muscle Contracted muscle
Thyro-arytenoid muscles
(Relax the cords)
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Muscles that close the
laryngeal inlet:
Transverse arytenoid
& ary-epiglottic
muscles
Transverse arytenoid
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Respiration
• During quiet respiration, the laryngeal inlet, vestibule, rima vestibuli, and rima glottidis are open. The
arytenoid cartilages are abducted and the rima glottidis is triangular shaped (Fig. 8.213A).
• During forced inspiration (Fig. 8.213B), the arytenoid cartilages are rotated laterally, mainly by the action
of the posterior crico-arytenoid muscles. As a result, the vocal folds are abducted, and the rima glottidis
widens into a rhomboid shape, which effectively increases the diameter of the laryngeal airway.
Phonation
• When phonating, the arytenoid cartilages and vocal folds are adducted and air is forced through the
closed rima glottidis (Fig. 8.213C). This action causes the vocal folds to vibrate against each other
and produce sounds, which can then be modified by the upper parts of the airway and oral cavity.
• Tension in the vocal folds can be adjusted by the vocalis and cricothyroid muscles.
Effort closure
Effort closure of the larynx (Fig. 8.213D) occurs when air is retained in the thoracic cavity to stabilize
the trunk, for example during heavy lifting, or as part of the mechanism for increasing intra-abdominal
pressure. During effort closure, the rima glottidis is completely closed, as is the rima vestibuli and
lower parts of the vestibule. The result is to completely and forcefully shut the airway.
Swallowing
During swallowing, the rima glottidis, the rima vestibuli, and vestibule are closed and the laryngeal
inlet is narrowed. In addition, the larynx moves up and forward. This action causes the epiglottis to
swing downward toward the arytenoid cartilages and to effectively narrow or close the laryngeal inlet
(Fig. 8.213E). The up and forward movement of the larynx also opens the esophagus, which is
attached to the posterior aspect of the lamina of cricoid cartilage. All these actions together prevent
solids and liquids from entry into the airway and facilitate their movement through the piriform fossae
into the esophagus.
Laryngeal function: (illustrating diagrams at next slide)
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Laryngeal function:
A. Quiet respiration.
B. Forced inspiration.
C. Phonation.
D. Effort closure.
E. Swallowing.
Fig. 8.213
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The major blood supply to the
larynx is by:
• superior laryngeal artery, br.
from superior thyroid of the
external carotid artery; and
• inferior laryngeal artery,
originates from the inferior
thyroid branch of the
thyrocervical trunk of the
subclavian artery .
Arterial supply of the larynx, left lateral view
Arterial supply of the larynx
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Venous drainage of the larynx, anterior view
• Superior laryngeal veins drain
into superior thyroid veins, which
in turn drain into the internal
jugular veins .
• Inferior laryngeal veins drain into
inferior thyroid veins, which drain
into the left brachiocephalic vein.
Lymphatics: drain regions above
and below the vocal folds:
• those above the vocal folds
follow the superior laryngeal
artery and terminate in deep
cervical nodes associated with
the bifurcation of the common
carotid artery;
• those below the vocal folds
drain into deep nodes
associated with the inferior
thyroid artery or with nodes
associated with the front of the
cricothyroid ligament or upper
trachea.
Venous drainage of the larynx
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Nerve supply of the Larynx
Motor:-
All intrinsic laryngeal muscles are supplied by
Recurrent laryngeal nerve EXCEPT the
cricothyroid  Supplied by external
laryngeal nerve.
Sensory:-
Above the level of the vocal cords: Internal
laryngeal nerve
Below the level of the vocal cords:
Recurrent laryngeal nerve.
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References:
• Gray's Anatomy for Students- Second edition
• Netter’s Clinical Anatomy, Second edition
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32. Thank you
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