The hypoglossal nerve is the motor nerve of the tongue and the ansa cervicalis is a motor nerve for the sub-hyoid muscles. The hypoglossal nerve seems to give the innervation of the thyrohyoid although it is a sub-hyoid muscle. Most of axons in the ansa cervicalis arise from the three first cervical nerves. These nerves are in close contact because of the cervical ontogeny of the tongue and the hypoglossal nerve. Nerve impulse in the superior root of the ansa cervicalis runs caudally to rostrally. This is why neurotization techniques using the superior root of the ansa cervicalis produce poor results in the treatment of facial palsy sequelae.
