loop of hypoglossal nerve definition

A loop in the cervical plexus consisting of fibres from the first three cervical nerves. Fibres from a loop between the C-1 and C-2 spinal nerves accompany the hypoglossal nerve for a short distance, leaving it as the superior root of the ansa cervicalis. Fibres from a loop between the C-2 and C-3 spinal nerves form the inferior root of the ansa cervicalis. Most commonly, the roots merge, forming the ansa cervicalis, which gives rise to branches innervating infrahyoid muscles.

Synonyms: cervical loop, loop of hypoglossal nerve.

(05 Mar 2000)