topic 17: The muscles, blood supply and innervation of the larynx. The histology of the larynx.

Question 1

Intrinsic muscles of larynx

Answer 1

These muscles control the tension of the vocal cords and the size and shape of the glottis.

Cricothyroid:
Tenses and elongates the vocal cords.
Thyroarytenoid:
Relaxes the vocal cords.

Posterior Cricoarytenoid:
Abducts the vocal cords, opening the glottis.
Lateral Cricoarytenoid:
Adducts the vocal cords, closing the glottis.

Transverse and Oblique Arytenoids:
Adduct the arytenoid cartilages, closing the posterior part of the glottis.

Vocalis:
Fine-tunes the tension of the vocal cords.

innervation: all innervated by reccurent laryngeal nerve except cricothyroid - External branch of the superior laryngeal nerve

Question 2

extrinsic muscles

Answer 2

These muscles position and stabilize the larynx during swallowing and speaking.

Suprahyoid Muscles:
Function: Elevate the larynx.
Examples: Mylohyoid, digastric, stylohyoid, and geniohyoid.

Infrahyoid Muscles:
Function: Depress the larynx.
Examples: Sternohyoid, sternothyroid, thyrohyoid, and omohyoid.

Question 3

blood supply

Answer 3

Superior Laryngeal Artery:

-Origin: Branch of the superior thyroid artery, which is a** branch of the external carotid artery**.
-Course: Accompanies the internal branch of the superior laryngeal nerve through the thyrohyoid membrane to supply the upper part of the larynx.

Inferior Laryngeal Artery:
-Origin: Branch of the inferior thyroid artery, which is a branch of the thyrocervical trunk from the subclavian artery.
-Course: Accompanies the recurrent laryngeal nerve to supply the lower part of the larynx.

Question 4

innervation

Answer 4

The larynx is innervated by branches of the vagus nerve (Cranial Nerve X).

Superior Laryngeal Nerve:
-Internal Branch: sensory innervation 4 mucosa above the vocal cords.
-External Branch: motor innervation 4 cricothyroid muscle.

Recurrent Laryngeal Nerve:
- motor innervation 4 all intrinsic muscles NOT cricothyroid.
- sensory innervation 4 mucosa below the vocal cords.

Question 5

histology

check own notes

Answer 5

Epithelium:

-Supraglottis (Above the Vocal Cords): Lined with pseudostratified ciliated columnar epithelium with goblet cells, which help trap and move debris.
-Vocal Cords: Lined with stratified squamous non-keratinized epithelium, which provides durability and protection against abrasion during phonation.
-Subglottis (Below the Vocal Cords): Lined with pseudostratified ciliated columnar epithelium.

Lamina Propria:

Vocal Ligament: Contains layers of elastin and collagen fibers, providing flexibility and strength to the vocal cords.
Reinke’s Space: A loose, gelatinous layer within the lamina propria of the vocal cords, allowing for their vibration during sound production.

Cartilage:

Hyaline Cartilage: Found in the thyroid, cricoid, and the majority of the arytenoid cartilages, providing rigid support.

Elastic Cartilage: Found in the epiglottis, corniculate, and cuneiform cartilages, providing flexible support.

Muscles:
Intrinsic Muscles: Striated skeletal muscle fibers, enabling voluntary control of the vocal cords for speech and breathing.