Cranial Nerves IX, X, XII: The Mouth

Published on 09/04/2015 by admin

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Last modified 09/04/2015

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Cranial Nerves IX, X, XII

The Mouth

BACKGROUND

Glossopharyngeal nerve: IX

• Sensory: posterior one-third of tongue, pharynx, middle ear.

• Motor: stylopharyngeus.

• Autonomic: to salivary glands (parotid).

Vagus nerve: X

• Sensory: tympanic membrane, external auditory canal and external ear.

• Motor: muscles of palate, pharynx, larynx (via recurrent laryngeal).

• Autonomic: afferents from carotid baroreceptors, parasympathetic supply to and from thorax and abdomen.

Hypoglossal nerve: XII

• Sensory: none.

• Motor: intrinsic muscles of the tongue.

MOUTH AND TONGUE: WHAT TO DO

Ask the patient to open his mouth.

Look at the gums.

• Are they hypertrophied?

Look at the tongue.

• Is it normal in size?

• Are there rippling movements (fasciculations)?

• Is it normal in colour and texture?

Ask the patient to put out his tongue.

• Does it move straight out or deviate to one side?

COMMON MISTAKES

• Small rippling movements of the tongue are normal when the tongue is protruded or held in a particular position.

• Fasciculations need to be looked for when the tongue is at rest in the mouth.

To assess weakness

Ask the patient to push his tongue into his cheek and test the power by pushing against it; repeat on both sides.

Test repeated movements

Ask the patient to put his tongue in and out as fast as he can, and move it from side to side. Look at the speed of tongue movement.

Ask the patient to say ‘ticker ticker ticker’ as fast as he can.

Test speech

See dysarthria (Chapter 2).

MOUTH: WHAT YOU FIND AND WHAT IT MEANS

• Gum hypertrophy: phenytoin therapy.

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