Question
Unilateral injury to the nerve marked by a red arrow in the picture below leads to all, EXCEPT?
A. Hemiatrophy of involved side.
B. Deviation of tongue towards the same side.
C. Loss of taste sensation in one half of the tongue.
D. Fasciculation of the tongue.
Show Answer
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Correct Answer » C
Explanation
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Ans;C. Loss of taste sensation in one half of the tongue
The nerve marked by a red arrow in the picture above represents the hypoglossal nerve.
The action of the hypoglossal nerve is entirely motor.
- Disorders affecting the function of the hypoglossal nerve lead to imbalanced action of the genioglossus muscles, causing tongue deviation toward the weak side.
- Supranuclear disease affecting the nerve results in paralysis of the tongue contralateral to the side of the lesion. Deviation of the tongue will occur away from the side of the lesion. Fasciculation and atrophy of the tongue are absent.
- When disease affects the hypoglossal nerve at the nuclear or infranuclear level, the clinical signs and symptoms are ipsilateral. There is dcviation of the tongue toward the side of the lesion, with associated atrophy of the intrinsic and extrinsic tongue musculature and fasciculation of the tongue. This constellation may lead to dysarthric speech.
NERVE SUPPLY OF TONGUE
MOTOR NERVES:
- All the intrinsic and extrinsic mucles, except the palatoglossus, are supplied by HYPOGLOSSAL NERVE.
- The palatoglossus is supplied by the cranial root of the ACCESSORY NERVE through the pharyngeal plexus.
SENSORY NERVES:
1. Anterior 2/3- Lingual nerve branch of mandibular division sensory- for general sensation (V3).
- Chorda tympani-branch of VII- carries taste from anterior 2/3 of tongue
- Accompany lingual nerve.
2. Posterior 1/3- Glossopharyngeal- both sensory & taste.
- Also carries sensation & taste from circumvallate papilla
3. The posterior most part of the tongue is supplied by the vagus nerve .
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