Larynx Anatomy

Question 1

General Features of Larynx

Answer 1

A. The larynx serves both a respiratory and voice-producing (phonation) function.

B. Connects pharynx to trachea; thus directing air to respiratory passages.

C. Also acts to prevent passage of food materials into the airways.

D. Located in the neck, anterior to CV3 – CV6.

E. Composed of cartilages, membranes, and muscles which control the rate and amount of air flowing through the larynx; thus altering the pitch, tone, and volume of voice.

Question 2

Internal Features of Larynx

Answer 2

A. Laryngeal aditus – superior opening from pharynx

B. Vestibule – area proximal (above) vestibular folds

C. Vestibular (false) folds

D. Rima vestibuli – opening between vestibular folds

E. Ventricle – between vestibular and vocal folds

F. True vocal folds

G. Rima glottidis – opening between true vocal folds

1. Shape varies depending on position of vocal folds
2. Variation in the tension and length of the vocal folds, and width of rima produces changes in pitch of the voice.

H. Glottis – rima glottidis plus vocal folds

I. Infraglottic cavity - distal (below) true vocal folds

Question 3

Clinical correlation cricoid cartilage

Answer 3

– landmark for CV6

1. Site where carotid artery can be compressed against CV6
2. Junction of larynx and trachea
3. Junction of pharynx and esophagus

Question 4

Tracheotomy

Answer 4

1. Obstruction of the upper airway can be overcome by puncturing the larynx or trachea.
2. Incision is made between the cricoid cartilage and the first tracheal cartilages.
3. Incision can also be made between the cricoid and thyroid cartilages (through the cricothyroid ligament).

Question 5

Laryngeal Cartilages

Answer 5

Thyroid, Cricoid, Arytenoid, Epiglottic, Corniculate, CUneiform

Question 6

Thyroid Cartilage

Answer 6

1. Lies anterior to CV4, CV5
2. Features
   a. Laminae (2) fuse anteriorly and remain open posteriorly.
   b. Superior horn – attached to hyoid bone by lateral thyrohyoid ligament
   c. Inferior horn – articulates with cricoid cartilage
   d. Laryngeal prominence (Adam’s apple)
   e. Superior thyroid notch
   f. Oblique line

Question 7

Cricoid cartilage

Answer 7

1. Lies anterior to CV6
2. Features
   a. Immobile ring attached via membrane to first tracheal cartilage
   b. Anterior arch
   c. Posterior lamina
   d. Articulates with arytenoid and thyroid cartilages

Question 8

Arytenoid cartilages

Answer 8

1. Lie perched atop the posterior portion of the cricoid cartilage
2. Features
   a. Apex – attaches to aryepiglottic fold
   b. Vocal process – attaches to vocal ligament
   c. Muscular process – attaches to posterior and lateral cricoarytenoid muscles

Question 9

Epiglottic cartilage

Answer 9

1. Leaf-shaped, elastic cartilage situated posterior to root of tongue.
2. Broad, superior end is free; inferior end is attached to the thyroid cartilage.
3. Muscles of the pharynx pull the thyroid cartilage against the epiglottis during swallowing to prevent food from moving into the larynx.
4. Ligaments
   a. Thyroepiglottic ligament
   b. Hyoepiglottic ligament
   c. Aryepiglottic ligament
   d. Glossoepiglottic ligaments (median and lateral)

Question 10

Corniculate cartilages

Answer 10

lie atop the apex of the arytenoid cartilages

Question 11

Cuneiform cartilages

Answer 11

lie within aryepiglottic folds

Question 12

Laryngeal Ligaments - External

Answer 12

1. Thyrohyoid membrane
   a. Attaches hyoid bone to superior border of thyroid cartilage
   b. Thickened laterally (lateral thyrohyoid ligament) and medially (median thyrohyoid ligament)
   c. Pierced by the internal laryngeal nerve and superior laryngeal artery.
2. Cricotracheal ligament – attaches cricoid to first tracheal cartilage
3. Hyoepiglottic ligament
4. Glossoepiglottic ligament

Question 13

Laryngeal ligaments- Intrinsic ligaments

Answer 13

Quadrangular ligament

Cricovocal (conus elasticus) ligament

Question 14

Quadrangular ligament

Answer 14

a. Attaches anteriorly to the thyroid and epiglottic cartilages
b. Attaches posteriorly to the arytenoid cartilage
c. Forms vestibular ligaments; covered with mucosa = vestibular fold
d. Forms aryepiglottic ligament; covered with mucosa = aryepiglottic fold

Question 15

*** Cricovocal (conus elasticus) ligament **

Answer 15

a. Attaches inferiorly to cricoid cartilage.
b. Attaches superiorly to thyroid and arytenoid cartilages.

c. Thickened regions:
1. Median cricothyroid ligament
2. Lateral cricothyroid ligament
3. Vocal ligament – extends from internal surface of thyroid lamina to vocal process of arytenoid; covered with mucosa = vocal fold

Question 16

Laryngeal folds

Answer 16

Vocal and Vestibular

Question 17

Vocal folds

Answer 17

1. Formed from mucosa overlying vocal ligament and vocalis muscle.
2. Vocal ligament – innermost portion of cricovocal ligament; extends from thyroid cartilage to vocal process of arytenoid cartilage.
3. Vocalis muscle – innermost portion of thyroarytenoid muscle.
4. Vocal ligaments change tension/length in order to control pitch of voice.

Question 18

Vestibular folds

Answer 18

1. Formed from mucosa overlying vestibular ligament

2. Covered with highly vascularized mucosa; contains many mucus-secreting glands.

Question 19

Joints of Larynx

Answer 19

Cricothyroid and cricoarytenoid joints

Question 20

Cricothyroid joint

Answer 20

1. Articulation between cricoid cartilage and inferior horn of thyroid cartilage.
2. Synovial – mainly gliding movements
3. Allows thyroid to glide on cricoid in order change vocal cord length.

Question 21

Cricoarytenoid joint

Answer 21

1. Articulation between cricoid cartilage and arytenoid cartilage.
2. Synovial – mainly gliding and rotational movements (condylar joint)
3. Allows arytenoid cartilages to rotate, glide toward one another.

Question 22

Primary motions of laryngeal cartilages

Answer 22

1. Rotation of arytenoid cartilages to abduct (posterior cricoarytenoid) and adduct (lateral cricoarytenoid) vocal ligaments.
2. Gliding of arytenoids to adduct vocal ligaments (to close rima glottitis) (transverse and oblique artenoids).
3. Rotating of thyroid cartilage on cricothyroid joint to increase (cricothyroid muscle) and decrease (thyroarytenoid muscle) tension on the vocal ligaments.

Question 23

cricothyroid muscle

Answer 23

tilts thyroid forward to elongate and tighten vocal ligament

Question 24

Transverse and oblique arytenoids

Answer 24

1. Adduct arytenoid cartilages

2. Close laryngeal inlet by approximating the arytenoid cartilages

Question 25

Thyroarytenoid

Answer 25

rotates thyroid cartilage back to shorten and loosen vocal ligament

Question 26

Vocalis muscle

Answer 26

1. Innermost portion of thyroarytenoid muscle 2. Lateral to vocal ligament 3. Locally controls vocal ligament; produces minute adjustments or vocal ligament tension and length.

Question 27

Innervation of laryngeal muscles

Answer 27

1. External branch of superior laryngeal n – cricothyroid | 2. Recurrent laryngeal nerve (inferior laryngeal n) – all other muscles

Question 28

Innervation of larynx

Answer 28

A. Superior laryngeal nerve (CN X) 1. Internal laryngeal nerve a. Pierces thyrohyoid membrane b. Provides: - --GVE-P and GVA proximal to true vocal folds (supraglottic region) - --SVA to epiglottic region of tongue 2. External laryngeal nerve – SVE to cricothyroid muscle B. Inferior laryngeal nerve (CN X) 1. Continuation of recurrent laryngeal nerve. 2. Enters larynx by passing inferior to inferior constrictor m. 3. Provides: a. GVE-P and GVA distal to true vocal folds (infraglottic region) b. SVE to all muscles of larynx, except cricothyroid

Question 29

CLINICAL CORRELATION: COUGH REFLEX

Answer 29

There is a very strong reflex, mediated by CN X, which functions to prevent foreign objects from entering the airways. When foreign objects (ex: food) enter the larynx, the superior laryngeal nerve is stimulated (GVA) and causes contraction of laryngeal muscles which close the larynx. Vagus nerve will stimulate a cough in order to force air out of the larynx. Injury to the superior laryngeal nn will ablate this protective function due to anesthesia of the laryngeal mucosa. Cough reflex – afferent limb is CN X; efferent limb is CN X.

Question 30

CLINICAL CORRELATION – Superior laryngeal nerve lesion

Answer 30

will result in loss of the cough reflex (loss of sensation to supraglottic region). The cricothyroid m will also be paralyzed which often causes a monotonous voice.

Question 31

CLINICAL CORRELATION: Choking and the Heimlich Maneuver:

Answer 31

If a foreign object enters the larynx, above reflex is engaged and the rima glottidis closes tightly. The Heimlich maneuver is used to dislodge the foreign object by increasing intrathoracic pressure.

Question 32

CLINICAL CORRELATION: Superior laryngeal nerve block

Answer 32

is administered when inserting an endotracheal tube. The needle is inserted halfway between the hyoid bone and superior border of the thyroid cartilage. The needle pierces the thyrohyoid membrane and anesthetic agent will bath the superior laryngeal n.

Question 33

CLINICAL CORRELATION: Injury to the recurrent laryngeal nerve

Answer 33

can occur with neck or thoracic damage or surgery. Recall that the left recurrent laryngeal nerve branches in the thorax (aortic aneurysms, tumors, enlarged lymph nodes in the thorax can compress and damage the recurrent laryngeal nerve). Injury to the nerve will affect the function of the larynx due to the fact that all but one laryngeal muscle are innervated by the recurrent laryngeal nerve. If damage is unilateral, patient will present with hoarseness; if bilateral will present with aphonia.

Question 34

Arterial supply of the larynx

Answer 34

1. Superior laryngeal artery a. Branch of superior thyroid artery b. Pierces thyrohyoid membrane c. Supplies larynx above true vocal folds 2. Cricothyroid artery a. Branch of superior thyroid artery b. Supplies cricothyroid muscle 3. Inferior laryngeal artery a. Branch of inferior thyroid artery b. Supplies larynx below true vocal folds

Question 35

Venous drainage of the larynx

Answer 35

1. Superior laryngeal vein → internal jugular vein | 2. Inferior laryngeal vein → left brachiocephalic vein

Question 36

Lymphatic drainage of the larynx

Answer 36

A. Proximal (above) true vocal folds → superior deep cervical lymph nodes B. Distal (below) true vocal folds → inferior deep cervical lymph nodes