Cranial Nerves V and VII: The Face

Published on 09/04/2015 by admin

Filed under Neurology

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1699 times

Cranial Nerves V and VII

The Face

BACKGROUND

Facial nerve: VII

Peripheral function can be summarised as ‘face, ear, taste, tear’:

With lower motor neurone (LMN) facial weakness, all muscles are affected.

With upper motor neurone (UMN) facial weakness, the forehead is relatively preserved.

FACIAL NERVE: WHAT TO DO

Look at the symmetry of the face.

Ask the patient to:

Look out for symmetrical movement.

Compare the strength of the forehead and lower face.

In LMN lesions you can see the eye turn upwards on attempted closure—Bell’s phenomenon.

Other functions of the facial nerve

Look at the external auditory meatus—the cutaneous distribution of VII. Note any vesicles suggestive of herpes zoster.

Provides taste to the anterior two-thirds of tongue. Taste is rarely tested and requires saline solution and sugar solution. A cotton bud is dipped in the solution and applied to the tongue and the patient is asked to identify it. Test each side of the anterior two-thirds and the posterior one-third.

FACIAL NERVE: WHAT YOU FIND

See Figure 11.3.

Bilateral facial nerve weakness can be easily missed unless tested for. Think of it if you feel that a patient seems impassive when you talk to him. He may not be depressed; his face might not be able to move!

Failure of the patient to smile when asked to whistle has been noted in patients with emotional paralysis due to parkinsonism: the ‘whistle–smile’ sign.

TRIGEMINAL NERVE: WHAT TO DO