Atlas of Human Anatomy by Netter

GUIDE

Head and Neck: Thyroid Gland and Larynx

Larynx: General Anatomy

Organ of phonation and sphincter guarding lower respiratory tract

Approximately 8 cm long

Connects oropharynx with trachea

Lies anterior to prevertebral muscles, fascia, and the bodies of C3-C6 vertebrae

Laryngeal skeleton
page 43
page 44

Comprised of three paired and three nonpaired cartilages

Epiglottic cartilage (epiglottis)

Leaf-shaped elastic cartilage

Posterior to root of tongue and hyoid bone, anterior to laryngeal inlet

Broad superior end is free

Inferior end attached in midline to angle of thyroid laminae by thyroepiglottic ligament

Quadrangular membranes run between lateral sides of epiglottic cartilage and arytenoid cartilages on either side

Upper free margin of quadrangular membrane + covering mucosa = aryepiglottic fold

During swallowing overlies laryngeal inlet

Thyroid cartilage

Composed of two flat laminae

Lower two thirds of laminae fuse in midline to form laryngeal prominence (Adam's apple)

Upper one third of laminae diverge to form superior thyroid notch

Posterior superior border of each plate projects superiorly as superior horns

Posterior inferior border of each plate projects inferiorly as inferior horns

Superior horns and superior borders of laminae attach to hyoid bone by thyrohyoid membrane

Cricoid cartilage

Signet ring shaped, signet (lamina) facing posteriorly

Strong, thick, complete circle of cartilage

Attached to inferior thyroid by median cricothyroid ligament

Attached to first tracheal ring by cricotracheal ligament

Arytenoid cartilages (paired)

Pyramid shaped with three sides

Articulate with lateral superior parts of cricoid lamina

Has three processes:

a. Apex at superior end

b. Vocal process projects anteriorly

c. Muscular process projects laterally

Apex: Corniculate cartilage sits atop; attaches to aryepiglottic fold

Vocal process: posterior attachment for vocal ligament

Muscular process: attachment for posterior and lateral cricoarytenoid muscles

Corniculate and cuneiform cartilages

Nodules in posterior aryepiglottic folds

Cuneiforms do not attach to other cartilages

Corniculates attach to apices of arytenoids

Membranes of the laryngeal skeleton

Cricothyroid ligaments

Median cricothyroid ligament

Lateral cricothyroid ligaments (conus elasticus)

Both attach to cricoid cartilage to inferior border of thyroid cartilage

Medial free edge of lateral cricothyroid ligaments = vocal ligaments, basis of true vocal cords

Quadrangular membrane

Inelastic connective tissue

Attaches lateral aspects of arytenoids and epiglottis

Lower free border = vestibular ligament (false vocal cord)

Covered by vestibular fold

Above vocal fold

Extends from thyroid cartilage to arytenoid cartilage

Upper free border forms aryepiglottic ligament

Covered with mucosa

Called aryepiglottic fold

Thyrohyoid membrane

Bridges gap between superior border and superior horns of thyroid cartilage and

Pierced by superior laryngeal vessels and internal laryngeal nerve

Mucous membrane

Respiratory epithelium except over true and aryepiglottic folds

This is composed of stratified squamous epithelium

Internal anatomy of the larynx