Nervus facialis

Nervus Facialis or the Facial Nerve is the seventh cranial nerve or simply CN VII. It emerges from the pons of the brainstem, controlling the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity. It also supplies preganglionic parasympathetic fibers to several head and neck ganglia.

Structure

The facial nerve is composed of approximately 10,000 neurons, 7,000 of which are myelinated and innervate the nerves of the face. The remaining 3,000 form the nervus intermedius, which is largely sensory but also contributes to the autonomic innervation of the lacrimal gland and the salivary glands.

Function

The facial nerve performs two major functions: motor and sensory. The motor function includes facial expression, closing the eyes, and closing the mouth. The sensory function involves taste from the anterior two-thirds of the tongue.

Motor Function

The facial nerve innervates the muscles of facial expression, which include the following groups: orbital, nasal, oral, and cervical. These muscles are responsible for many facial expressions, including frowning, smiling, raising the eyebrows, and closing the eyes.

Sensory Function

The sensory part of the facial nerve, the nervus intermedius, carries taste sensations from the anterior two-thirds of the tongue via the chorda tympani. It also carries a small amount of cutaneous sensation from the skin in and around the ear.

Clinical Significance

Damage to the facial nerve can result in facial paralysis. This can occur as a result of several medical conditions, including Bell's palsy, Lyme disease, and stroke. The most common cause is Bell's palsy, a condition that causes sudden, unilateral facial paralysis.

See Also

• Cranial nerves
• Bell's palsy
• Stroke