Hypoglossal nucleus
The hypoglossal nucleus is where cranial nerve XII (hypoglossal nerve) originates. Axons of the neurons exit the medulla ventrolaterally between the medullary pyramids and the inferior olive. The nerve then passes through the hypoglossal foramen, emerging from the base of the skull and innervating the ipsilateral muscles of the tongue. Therefore, lesion of the hypoglossal nucleus or nerve may result in paralysis, fasciculations, and eventual atrophy of the ipsilateral muscles of the tongue. The hypoglossal nerve can be damaged at the hypoglossal nucleus (nuclear), above the hypoglossal nucleus (supranuclear), or at the motor axons (infranuclear).
