LARYNX

Valve separating the trachea from the upper

aerodigestive tract b. CRICOID
• Only complete rigid ring within the airway
Functions: • Signet ring shape
• Organ of communication “Voice Box” • Narrow anteriorly, broadest posteriorly
- Voice production (overlaid function) • Swelling within this area is dangerous because
• Protection of airway/ prevention of aspiration it can
during swallowing • Impede the airflow
• Respiration
• Necessary for coughing and valsalva maneuver c. EPIGLOTTIS
• Leaf-shaped structure
Anatomical Units: • Attached inferiorly to the anterior interior
1. Skeleton surface of
2. Intrinsic Muscles • the thyroid cartilage
3. Extrinsic Muscles • Upper margin is free & projects into the
4. Vocal Fold Structure hypopharynx
• above the glottis opening
1. LARYNGEAL SKELETON • Important for swallowing

3 PAIRS OF SMALLER CARTILAGES

a. ARYTENOID CARTILAGES
• Pyramid shaped; described as grain of rice
(small)
• Located superior to the cricoid cartilage in the
posterior part of the larynx
• Base articulates on either side with the posterior
aspect of the upper border of the cricoid lamina
• Apex is pointed and articulates with the
corniculate cartilage
• Vocal Process
− At the anterior angle of the base
− For the attachment of the vocal fold
BONE (Hyoid Bone) • Muscular Process
- The only bone - At the lateral angle
- Technically not part of the larynx - For the attachment of the posterior and lateral
- Provides muscular attachments from the above cricoarytenoid muscles
that aid in laryngeal motion
b. CORNICULATE CARTILAGES
CARTILAGES • Small, paired, fibroelastic cartilages
3 UNPAIRED CARTILAGES • Sit laterally to each of the arytenoids
a. THYROID • Completely embedded within the aryepiglottic
• Composed of 2 rectangular laminae that are folds
fused anteriorly in the midline; technically not • Provides additional structural support to
paired aryepiglottic fold
• Has a posterior articulation with the cricoid • Remnant; used as landmark
cartilage via the cricothyroid joint
• Where the vocal folds are housed & are c. CUNEIFORM CARTILAGES
anteriorly attached to its inner surface • Cricoarytenoid joint paired elastic cartilages
• Sit on top of and move with the corresponding
arytenoid
 - Thyroarythenoid

JOINTS

A. CRICOTHYROID
• Synovial joint • Runs from a vertical line on the interior surface of the
• Formed from the articulation of the inferior thyroid cartilage angle and adjacent to the external
cornua of the thyroid cartilage with facets on the surface of the cricothyroid ligament to the
cricoid lamina anterolateral surface of the arytenoid cartilage
• 2 Major Actions
− Antero:posterior sliding
• Bulk of vocal fold
− Rotation of the inferior thyroid cornu upon
• Each muscle consists of 2 parts:
the cricoid cartilage
- Vocalis
- Thyroepiglottic
B. CRICOARYTENOID • Functions
• Primary moving structure of the intrinsic larynx B.
• Arytenoids articulate with the cricoid cartilage ABDUCTOR MUSCLE
forming multiaxial joints a. POSTERIOR CRICOARYTENOID
• Movements of the joints changes the distance − Draws the arytenoid cartilages forward → relaxes &
between: shortens the vocal folds
− Rotate the arytenoid cartilages inward → adducts
the vocal folds & narrows the glottis opening
- Adducts/ contracts of the vocal folds
2. INTRINSIC LARYNGEAL MUSCLES
• Extends from the oval depression on the posterior
surface of the cricoid lamina on each side
A. ADDUCTOR MUSCLES • Extends upward to the muscular process of the
• Each side extends from the upper border of the arytenoid cartilages on the same side
arch of the cricoid cartilage to the muscular process of • Function
the arytenoid cartilage on the same side − Rotates the arytenoid cartilages laterally →
• Function abducts the vocal folds
- Rotates the arytenoid cartilages medially → − Only active abductor of the larynx
adducts the vocal folds − If paralyzed, patient cannot breathe because
gate to airways is block by folds
a. THYROARYTENOID Joan Marie Sales 2 [OHNS] Larynx
b. LATERAL CRICOARYTENOID MD 2017 :3D
c. INTERARYTENOID
C.
TENSOR MUSCLES

•
a. CRICOTHYROID MUSCLE
••
• Does not insert on the arytenoid cartilage
Single muscle that extends between the posterior
• No direct action on arytenoid motion
surfaces of each arytenoid cartilage Transverse &
• Connects the anterior edges of the thyroid &
oblique set
cricoid
Function
cartilages
ADDUCTOR
• Very thick muscle
ABDUCTOR
• Function
TENSOR
- Contraction → pulls the 2 cartilages closer together
- Thyroarytenoid - Lateral
(down anteriorly) → increases the distance between
Cricoarytenoid - Interarytenoid
the anterior commissure & cricoid → higher pitch
- Posterior Cricoarytenoid
A.
- Cricothyroid
B.
2. VOCAL LIGAMENT
4. 3. UNDERLYING MUSCLE
STERNOHYOID, THYROHYOID, OMOHYOID
! Innervated by the ansa cervicalis ELEVATORS
! Exert caudal traction on the larynx DEPRESSORS
! Caudal traction on the larynx + downward traction
on the - Digastric
trachea during inspiration → abduction of the vocal folds - Mylohyoid
GENIOHYOID, ANTERIOR BELLY OF THE DIGASTRIC, - Genioglossus
MYLOHYOID & STYLOHYOID - Stylohyoid
! Exert a cephalad force - Stylopharyngeus - Thyrohyoid
- Omohyoid
3. - Sternohyoid
EXTRINSIC LARYNGEAL MUSCLES - Sternothyroid
(https://droualb.faculty.mjc.edu/Lecture%20Notes/Unit
%203/muscles%20with%20figures.htm) *usually anterior muscles
(Dotted lines show movement of thyroid cartilage during CERVICAL STRAP MUSCLES
contraction)
SUPERIOR SUSPENSION
VOCAL FOLD STRUCTURE - Thyrohyoid
- Sternohyoid - Sternothyroid - Omohyoid
Vocal Cord → now called vocal fold since it is actually a
fold of tissue - Digastric - Mylohyoid - Stylohyoid
MICROANATOMY OF THE VOCAL FOLDS Joan Marie Sales 3 [OHNS] Larynx
! Allows the loose & pliable superficial mucosal layers MD 2017 :3D
to vibrate
freely over the stiffer structural underlayers
TRUE VOCAL FOLD

! 3 Major Layers
1. MUCOSA
! Highly specialized for its vibratory function ! Can also
be divided into layers:
Superior View

(https://www.pinterest.com/pin/397935317050851305/
)
• Squamous epithelium (most superficial layer) - To
maintain the shape of the vocal folds

• 3 layers of Lamina Propria

- Deep to the epithelium, each of increasing
rigidity
- Superficial layer of the Lamina Propria, or
SLP (most superficial layer, mostly cellular & composed
of ECM proteins, water, and loosely arranged fibers
of collagen & elastin)