Sternomastoid Muscle

STRUCTURE AND POSITION

Sternocleidomastoid is present on anterior side of the Neck superficially.
It is easily visible on rotation of neck to one side and is a cylindrical mescle.
It is a paired muscle and present on both sides of the neck.

ATTACHMENTS

Sternocleidomastoid has an origin and an insertion as follows :

Origin : Sternocleidomastoid has a broad origin from the superior aspect of the Manubrium of the Sternum and also from the superior aspect of the medial third of Clavicle.
It runs obliquely in upwards and lateral direction from its origin.
Insertion : Sternocleidomastoid is inserted into the lateral sides of the Mastoid Process and Superior Nuchal Line.

BLOOD SUPPLY

Sternocleidomastoid Muscle is supplied via branches of Posterior Auricular, Occipital, Superior Thyroid Artery. It is also supplied by Suprascapular and Superficial Cervical Arteries which are branches of the Subclavian Artery.

NERVE SUPPLY

Sternocleidomastoid is innervated by the Accessory Nerve, and also by the Ventral Rami of the C2,C3 and C4 spinal nerves.

ACTION

Sternocleidomastoid Muscle can flex or extend the Head. It also pulls and rotates it to the opposite side. Sternocleidomastoid can also raise the Rib Cage.

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