22 - Facial Nerve

Abstract

Upon leaving its nucleus, the facial nerve (CN VII) winds around the abducent nerve (CN VI) nucleus, producing the facial colliculus. It emerges at the lower border of the pons; and at the internal auditory meatus, enters a long bony canal opening at the stylomastoid foramen at the base of the skull. It supplies the muscles of facial expression, the occipital belly of the occipitofrontalis, the stapedius, the stylohyoid, and the posterior belly of the digastric. The upper half of the facial nucleus receives a bilateral corticobulbar innervation from the motor cortex; the lower half receives only a contralateral innervation. The nervus intermedius travels in part with CN VII. The superior salivatory nucleus provides the preganglionic parasympathetic neurons of the greater petrosal nerve (for lacrimal and nasal glands via the pterygopalatine ganglion) and the chorda tympani (for submandibular and sublingual glands via the submandibular ganglion). The geniculate ganglion of CN VII has pseudounipolar neurons that receive taste from the anterior two-thirds of the tongue via the chorda tympani and the palate via the greater petrosal nerve. A few pseudounipolar neurons supply the skin in and around the external acoustic meatus.