Infrahyoid muscles

This presentation is about the infrahyoid muscles in detail.

1. Infrahyoid Muscles / Ribbon Muscles

2. The infrahyoid muscles are: a. Sternohyoid b. Sternothyroid c. Thyrohyoid d. Omohyoid. These ribbon muscles have the following general features. a. They are arranged in two layers, superficial (sternohyoid and omohyoid) and deep (sternothyroid and thyrohyoid). b. All of them are supplied by the ventral rami of first, second and third cervical spinal nerves. c. Because of their attachment to the hyoid bone and to the thyroid cartilage, they move these structures. d. Sternohyoid, superior belly of omohyoid, sternothyroid lie superficial to the lateral or superficial convex surface of the thyroid gland. e. The anterior surface of isthmus of thyroid gland is covered by right and left sternothyroid and sternohyoid muscles.

3. Muscle Proximal Attachment Distal Attachment Nerve Supply Action Sternohyoid a. Posterior surface of manubrium sterni
b. Adjoining pafts of the clavicle and the posterior
sternoclavicular ligament medial part of lower border of hyoid bone Ansa Cervicalis Depresses the hyoid bone following its elevation during
swallowing and during
vocal movements Sternothyroid:
It lies deep to the
sternohyoid a. Posterior surface
of manubrium sterni
b. Adjoining part of
first costal cartilage Oblique line on the
lamina of the thyroid
cadilage Ansa cervicalis
C1, C2, C3 Depresses the larynx
after it has been elevated
in swallowing and in
vocal movements Thyrohyoid:
It lies deep to the
sternohyoid Oblique line of thyroid
cartilage Lower border of the
body and the greater
cornua of the hyoid
bone C1 through
hypoglossal nerve a. Depresses the hyoid
bone
b. Elevates the larynx when the hyoid is fixed by the suprahyoid muscles Omohyoid:
lt has an inferior belly, a common tendon and a superior belly. lt arises by the inferior belly, and is inserted through the superior belly a. Upper border of scapula near the suprascapular
notch
b. Adjoining part of suprascapular ligament Lower border of body of hyoid bone lateral to the sternohyoid. The central
tendon lies on the internal jugular vein at the level of the cricoid
cartilage and is bound to the clavicle by a fascial pulley Superior belly by the superior root of the ansa cervicalis, and inferior belly by inferior root of
ansa cervicalis Depresses the hyoid
bone following itelevation during swallowing or in vocal movements