Sternocleidomastoid Muscle: Function & Anatomy – Human Body | Kenhub

Hello again, everyone. It’s Matt from Kenhub!
And in this tutorial, we will discuss the function and anatomy of the sternocleidomastoid
muscle. The sternocleidomastoid muscle is a two-headed
muscle of the neck. The two heads are called the sternal head and the clavicular head. The muscle lies very superficially so that
it is both easily visible and palpable. The carotid pulse may be felt in the middle third
of the front edge. The sternocleidomastoid is innervated by the
accessory nerve and by direct branches of the cervical plexus. The sternal head originates from the sternal
manubrium and the clavicular head from the middle part of the clavicle. The insertion is the mastoid process of the
temporal bone and the superior nuchal line of the occipital bone. Under the sternocleidomastoid region runs
a neurovascular bundle containing the common carotid artery, the internal jugular vein,
the vagus nerve, highlighted here in green, and the cervical ansa. A unilateral contraction of the sternocleidomastoid
muscle flexes the cervical vertebral column to the same side called lateral flexion and
rotates the head to the opposite side. A bilateral contraction leads to an elevation
of the head, otherwise called dorsal extension. In addition, it supports inspiration, providing
that the head is holding still. This video is more fun than reading a textbook,
right? If you want more videos, interactive quizzes, articles, and an atlas of human anatomy,
click on the “Take me to Kenhub” button. It is time to say goodbye to your old textbooks
and say hello to your new anatomy learning partner, Kenhub! See you there!


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