ABSTRACT
The ansa cervicalis has two roots: the upper root leaves the hypoglossal nerve where it curves round the occipital artery, and contains only fibres from the first cervical spinal nerve. The lower root, or nervus descendens cervicalis, contains fibres from the second and third cervical spinal nerves. The two roots form the ansa cervicalis, from which branches supply the sternohyoid, sternothyroid and the inferior belly of the omohyoid (Williams et al., 1995). Aside from some German authors who met halfway and refered to it as “Plexus hypoglossocervicalis” (Rodrigues, 1929), most anatomists of the last centuries described this anastomosis between the cervical plexus and the hypoglossal nerve either as ansa hypoglossi, or as ansa cervicalis. In the first case, it was believed to arise from the hypoglossal nerve and join the cervical plexus, in the second case it was to be inferred that this ansa was formed only by fibres belonging to the cervical plexus.
