Ansa cervicalis

The ansa cervicalis (or ansa hypoglossi in older literature) is a loop of nerves that are part of the cervical plexus.

Branches from the ansa cervicalis innervate the sternohyoid muscle, sternothyroid muscle, and the inferior belly of the omohyoid muscle.

Roots
Two roots make up the ansa cervicalis.


 * The superior root of the ansa cervicalis is formed by a branch of spinal nerve C1. These nerve fibers travel in the hypoglossal nerve before leaving to form the superior root.  The superior root goes around the occipital artery and then descends in the carotid sheath.  It sends a branch off to the superior belly of the omohyoid muscle and is then joined by the inferior root.


 * The inferior root is formed by fibers from spinal nerves C2 and C3.