24. Larynx Anatomy

Question 1

Describe the anatomic locations of:
Epiglottis
Thyroid Gland
Piriform Recess
Median Glossoepiglottic fold
Valleculae
Glottis

Answer 1

Epiglottis: above larynx (entryway)
Thyroid gland: way below larynx
Piriform recess: area on either side, between thyroid and cricoid cartilages, where food commonly gets trapped
Median glossoepiglottic fold: where tongue and epiglottis meet midline
Valleculae: spaces (spit traps) on either side of ME fold, helping reduce our need to swallow
Glottis: adducts airway for speech (true vocal folds)

Question 2

What are the pharyngeal constrictors and what runs between them?

Answer 2

(Auditory tube and levator palati)
Superior Constrictor - to buccinator m.
(CN IX)
Middle Constrictor - to hyoid bone
(Internal Laryngeal N., Superior Laryngeal A.)
Inferior Constrictor - to thyroid/cricoid cartilages

Question 3

Describe the locations of:
Arytenoid Cartilage
Vocal Ligament
Vestibule
Ventricle
Rima Glottidis
Infraglottic Cavity
Upper/Lower boundaries of Laryngopharynx
Triangular Membrane
Quadrangular Membrane

Answer 3

Arytenoid Cartilage - attach to vocal cords and cricoarytenoid m.
Vocal Ligament - runs from arytenoid to thyroid cartilages, stretching it increases pitch
Vestibule - above false (vestibular) vocal folds
Ventricle - b/w false and true vocal folds (resonating chamber)
Rima Glottidis - fissure b/w true cords
Infraglottic Cavity - below folds
Laryngopharynx - from tip of epiglottis to bottom of cricoid
Triangular Membrane: area between cricoid and thryroid - bounds infraglottic cavity, upper edge is VOCAL LIGAMENT
Quadrangular Membrane: bounds vestibule, lower edge is FALSE LIGAMENT

Question 4

What are the functions of the intrinsic larynx muscles:
Aryepiglottic m.
Oblique + Transverse Arytenoid m.
Posterior Cricoarytenoid m.
Lateral Cricoarytenoid m.
Cricothyroid m.
Thyroarytenoid m.
Thyroepiglottic m.

Answer 4

A-E m. = pulls epiglottis back to close larynx
O + T A m. = complete adduction of vocal cords, pulls arytenoids together
PCA m = ABDUCTS vocal cords (opens airway, rotates arytenoids open)
LCA m = ADDUCTS vocal cords (rotates arytenoids closed, makes voice a whisper)
CT m = pulls thyroid down/forward - stretches vocal cords = raises pitch
TA m = upper part is vocalis m., shortens vocal folds to lower pitch
TE m. = pulls epiglottis forward to open airway

Question 5

What muscles are innervated by the recurrent laryngeal nerve? What innervates the infrahyoid strap muscles (and how do they alter the voice)?

What are the three larynx branches in the neck?

Answer 5

RLN: all muscles in larynx except cricothyroid (causes hoarseness if unilateral damage)
Ansa cervicalis innervates strap m., which move larynx up/down to change volume

1. Pharyngeal Branch = to constrictors and palate muscles (except tensor palati) - MOTOR
2. Superior Laryngeal N.
   a. Internal Laryngeal n. = visceral sensory above vocal cords
   b. External Laryngeal n. = motor to cricothyroid
3. Recurrent (Inferior) Laryngeal N. = motor to all other intrinsic laryngeal muscles, visceral sensory below vocal cords

2+3 have parasymps

Question 6

Where do they thyroid and cricoid cartilages develop from?
Where do the larynx and airway develop from?
What is unique about the newborn airway?

Answer 6

Arch 4 = thyroid cartilage and epiglottis
Arch 6 = cricoid cartilage

Larynx + Airway = ventral splanchnopleure extensions of foregut (endoderm)

Newborn: short pharynx = epiglottis overlaps with soft palate = obligate nasal breathers and easier to breathe when suckling