Ansa cervicalis

Ansa cervicalis is also known as Ansa hypoglossi owing to the origin of one of it's roots from the hypoglossal nerve. It is a thin nerve loop in the neck lying embedded in the carotid sheath and lower part of the larynx. It supplies the infrahyoid muscles.

Formation

Ansa cervicalis is formed by a superior root and an inferior root. Superior root is the continuation of the descending branch of the hypoglossal nerve. It’s fibres are inturn derived from C1 root. This root descends over the internal carotid and common carotid arteries. The inferior root is derived from C2 and C3 spinal roots. As this root descends it winds round the internal jugular vein and then continues anteroinferiorily to join the superior root in front of the common carotid artery.

Distribution

Superior root supplies the superior belly of omohyoid and inferior root supplies the sternohyoid, the sternothyroid and the inferior belly of omohyoid.