Download Larynx

LARYNX
Larynx
• Larynx is an air passage, a
sphincter and an organ of
phonation
• Situated in the anterior
midline of neck
• Extends from upper border of
epiglottis to lower border of
cricoid cartilage
• Lies opposite vertebral level C3
- C6 ( C1-C4 in children)
• Communicates with
laryngopharynx, Below
continuous with the trachea.
Skeleton of the larynx
• Made up of cartilages
• Connected by membranes and ligaments and moved by muscles
• Lined by mucous membrane
Cartilages
• Unpaired cartilages
– Epiglottis
– Thyroid
– Cricoid
• Paired cartilages
– Arytenoid
– Corniculate
– Cuneiform
Thyroid cartilage
• Largest laryngeal cartilage
• Made up of hyaline cartilage
• Consist of two laminae meeting in the
midline at the thyroid angle or
Adam's apple.
• Posterior borders of each lamina is
drawn upward into a superior cornu
and downward into inferior cornu.
Cricoid cartilage
• Shaped like a signet ring and lies below
the thyroid cartilage
• It has narrow anterior arch and a broad
posterior lamina
• On each side of the lateral surface is a
circular facet for articulation with the
inferior cornu of the thyroid cartilage
• Upper border of posterior lamina
articulate with base of the arytenoid
cartilage
Arytenoid cartilages
•
Two in number, pyramidal
shaped
•
Situated at the back of the
larynx,
•
It has an apex above which
supports the corniculate and
cuneiform cartilages
•
Base articulates with lamina of
cricoid cartilage
•
It two processes project from
the base
Corniculate and cuneiform cartilages
• Corniculate cartilage: two
small nodules that
articulate with the apex of
the arytenoid cartilage
• Cuneiform cartilages: two
rod like pieces of cartilages
that articulate with the
corniculate cartilage
Epiglottis
• Leaf shaped elastic cartilage
• Situated behind the root of
the tongue
• Its lower end connected with
the back of the thyroid
cartilage
• It is connected in front with
the body of the hyoid bone
• Sides of the epiglottis
connected to the arytenoid
cartilages by aryepiglottic
folds.
Membranes and ligaments of the
larynx
Thyrohyoid membrane:
It connects upper border of
thyroid cartilage below and
posterior surface of the hyoid bone
above
- It is thickened in the midline to
form the median thyrohyoid
ligament
-Posterior borders of the membrane
also thickened to form the lateral
thyrohyoid ligaments
-pierced by internal laryngeal nerve
and superior laryngeal vessels
•
-
Fibroelastic membrane of the larynx
•
•
•
Lies beneath the mucous
membrane of the larynx
Upper portion is called
quadrangular membrane
Lower portion is called cricovocal
membrane
Quadrangular membrane:
- extends between the epiglottis
and arytenoid cartilages
- Its thickened lower margin forms
the vestibular ligament
• Cricovocal membrane:
- connects the cricoid cartilage
to arytenoid and thyroid
cartilage
- Upper thickened border is
called vocal ligament
- Anterior of each vocal
ligament is attached to the
deep surface of the thyroid
angle, posterior end to the
vocal process of the arytenoid
cartilage.
Ligaments of larynx
Hyoepiglottic ligament:
attaches the epiglottis to
the hyoid bone
Thyroepiglottic ligament:
attaches the epiglottis to
the thyroid cartilage
Cricotracheal ligament:
connects lower margin of
the cricoid cartilage to the
first ring of the trachea
Inlet of the larynx
• Communication between
larynx and laryngeal part
of the larynx
• Boundaries:
- In front: upper margin of
the epiglottis
- Laterally: aryepiglottic
fold
- Behind: inter arytenoid
fold
Cavity of the larynx
•
•
1.
•
•
•
Extends from inlet to the
lower margin of the cricoid
cartilage
Divided into 3 parts:
Vestibule or upper part:
Extends from the upper
border of the epiglottis to
the vestibular folds
Vestibular folds projects
medially which is a
thickened lower portion of
the quadrangular
membrane
Rima vestibuli: gap
between the vestibular folds
Cavity of larynx
Cavity of the larynx
2.
•
•
•
Middle part:
Extends from the level of
vestibular fold to the vocal fold
The vocal folds are white and
contain vocal ligament
Vocal ligaments extend from the
deep surface of the thyroid
angle to the vocal process of
the arytenoid cartilage
Cavity of the larynx
• Rima glottidis:
- Gap between the vocal
folds in front and the
vocal process of arytenoid
cartilage behind
- Lined by stratified
squamous epithelium
- Devoid of sub mucosa
Rima glottidis
Cavity of the larynx
• Sinus of the larynx: recess
between the vestibular and vocal
folds
• Saccule of the larynx: diverticulum
extends upwards from sinus of the
larynx between the thyroid cartilage
and vestibular fold.
3. Lower part:
• Extends from the vocal fold to the
lower border of cricoid cartilage
• Its walls are formed by cricothyroid
ligament and cricoid cartilage
Muscles of the larynx
• Divided in to two groups (1)
extrinsic (2) intrinsic
Extrinsic muscles:
• Includes elevators and
depressors of larynx
• Elevators: digastric,
thyrohyoid, stylohyoid,
mylohyoid and geniohyoid
• Depressors: sternothyroid,
sternohyoid and omohyoid
Intrinsic muscles
1. Cricothyroid:
Origin: side of the cricoid
cartilage
Insertion: lower border and
inferior cornu of the thyroid
cartilage
Action: tenses vocal cords
2. Posterior cricoarytenoid:
Origin: back of cricoid lamina
Insertion: muscular process of
arytenoid cartilage
Action: abducts the vocal cords
Intrinsic muscles
3. Lateral cricoarytenoid:
Origin: upper border of cricoid cartilage
Insertion: muscular process of arytenoid
cartilage
Action: adducts the vocal cords
4. Transverse arytenoid:
Origin: back of arytenoid cartilage
Insertion: back of the opposite arytenoid
cartilage
Action: closes the posterior part of the rima
glottidis by approximating arytenoid
cartilages
5. Oblique arytenoid: extends from the
muscular process of arytenoid artilage to
the vocal process of opposite arytenoid
cartilage
Intrinsic muscles
6. Thyroarytenoid
Origin: inner surface of thyroid cartilage
Insertion: arytenoid cartilage
7. vocalis: It extends from the vocal process of arytenoid
cartilage to the deep surface of thyroid angle
Action: ralaxes the vocal cords
8. Aryepiglotticus: extends from the arytenoid cartilage to
the side of epiglottis
Action: close the laryngeal inlet
9. Thyroepiglottis:
Origin: medial surface of thyroid cartilage
Insertion: lateral margin of the epiglottis
Action: widens the inlet
Adductors of the Vocal Folds
Abductor of Larynx
Movements of the vocal cords
Nerve supply
• Sensory supply
- Above the vocal folds: internal
laryngeal nerve
- Below the vocal cords:
recurrent laryngeal nerve
• Motor supply:
- All intrinsic muscles supplied
by recurrent laryngeal nerve
- Exception: cricothyroid –
external laryngeal nerve
Blood supply and lymph drainage
• Above the vocal folds:
superior laryngeal
artery
• Below the vocal folds:
inferior laryngeal
artery
• Lymph vessels drain
into deep cervical
lymph nodes
Damage to laryngeal nerves
• Recurrent laryngeal nerve:
• Unilateral
– Paralysis of vocal folds (midway between
abduction and adduction)
– Hoarseness of voice initially
– Compenates by other fold within weeks
– Normal respiration
• Bilateral:
– Loss of voice
– Stridor ( noisy respiration)
– Neutral position ( cadaveric position)
• Partial damage:
– Paralysis of abductors than adductors
– When bilateral acute breathlessness (dyspnea)
• External laryngeal nerve:
– Weakness of voice due to loss of vocal cord
tension