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.
Sternohyoid
Proximal Attachment
a. Posterior surface of manubrium sterni
b. Adjoining pafts of the clavicle and the posterior sternoclavicular ligament
Distal Attachment
medial part of lower border of hyoid bone
Nerve Supply
Ansa Cervicalis
Action
Depresses the hyoid bone following its elevation during swallowing and during vocal movements
Sternothyroid:
It lies deep to the sternohyoid
Proximal Attachment
a. Posterior surface of manubrium sterni
b. Adjoining part of first costal cartilage
Distal Attachment
Oblique line on the lamina of the thyroid cartilage
Nerve Supply
Ansa cervicalis C1, C2, C3
Action
Depresses the larynx after it has been elevated in swallowing and in vocal movements
Thyrohyoid:
It lies deep to the sternohyoid
Proximal Attachment
Oblique line of thyroid cartilage
Distal Attachment
Lower border of the body and the greater cornua of the hyoid bone
Nerve Supply
C1 through hypoglossal nerve
Action
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
Proximal Attachment
a. Upper border of scapula near the suprascapular notch
b. Adjoining part of suprascapular ligament
Distal Attachment
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
Nerve Supply
Superior belly by the superior root of the ansa cervicalis, and inferior belly by inferior root of ansa cervicalis
Action
Depresses the hyoid bone following elevation during swallowing or in vocal movements
----------------------------------------------------------------------------------------------------------------
My website - human-anatomy-lessons.busines...
My Blog - human-anatomylessons.blogspot...
----------------------------------------------------------------------------------------------------------------
Follow me in blogspot - human-anatomylessons.blogspot... _________________________________________________________________________________________________________________ Visit my blogs - humananatomyonline.in/
Contact me @ t.me/humananatomylessons