NCBI Bookshelf. Nathan R. Walker ; Rakesh K. Mistry ; Thomas Mazzoni.
Facial Nerve Palsy - StatPearls - NCBI Bookshelf
A facial palsy is weakness or paralysis of the muscles of the face. The facial nerve arises in the pons formed as separate sensory and motor roots , before travelling in the internal acoustic meatus, very close to the inner ear. As they enter the facial canal, the two roots fuse to form a single facial nerve, before giving off intracranial branches of the greater petrosal nerve, nerve to stapedius, and chorda tympani. The facial nerve then exits the facial canal and the cranium via the stylomastoid foramen. The first extracranial branches given off are the posterior auricular nerve, nerve to digastrics, and nerve stylohyoid. The facial nerve then enters the parotid gland, dividing into terminal branches of the Temporal, Zygomatic, Buccal, Marginal mandibular, and Cervical branches.
Facial motor nucleus
The facial nerve cranial nerve VII courses a long pathway beginning in the precentral gyrus and ending at the facial muscles, lacrimal and salivary glands, and structures of the inner ear. Lesions along this pathway, clinically divided into upper and lower motor neuron lesions, present with unique characteristics that assist the physician in identifying the lesion site. The sequelae particularly of peripheral CN VII palsies, may result in significant and chronic damage to the cornea that may be challenging for the physician and patient. This is a preview of subscription content, access via your institution.
The facial motor nucleus is a collection of neurons in the brainstem that belong to the facial nerve cranial nerve VII. These lower motor neurons innervate the muscles of facial expression and the stapedius. The nucleus is situated in the caudal portion of the ventrolateral pontine tegmentum. Its axons take an unusual course, traveling dorsally and looping around the abducens nucleus , then traveling ventrally to exit the ventral pons medial to the spinal trigeminal nucleus. These axons form the motor component of the facial nerve , with parasympathetic and sensory components forming the intermediate nerve.