Abstract :
Ansa cervicalis, a nerve loop formed by descendens hypoglossi contributed by C1 spinal nerve and descendens cervicalis, by C2 and C3 spinal nerves, innervates the infrahyoid muscles. An unusual formation of ansa cervicalis was noted in a 60-year-old female cadaver, bilaterally. On the left side, fibres from the hypoglossal and vagus nerves contributed to the formation of descendens vago-hypoglossi. Fibers from the ventral rami of C2 and C3 spinal segments ran downwards separately as a double descendens cervicalis and united at the loop formation. A similar variation was observed on the right side with a normal descendens cervicalis. The vago-hypoglossal anastomosis was longer on the left side than on the right. The neurofascial band between the vagus and hypoglossal nerve may lead to internal carotid artery stenosis. Ansa cervicalis is surgically significant, especially during laryngeal reinnervation procedures for recurrent laryngeal nerve palsy. The variation in the formation and course of the ansa cervicalis may significantly alter and complicate interventional procedures like neurorrhaphy, neck dissection or anterior cervical spinal approach.
Keyword :
Vagus nerve, Hypoglossal nerve, Cervical nerves, Strap muscles, Anastomosis