Right 12th nerve damage leads to?
Ans. (b) Tongue deviation to right on protrusionRef: Harrison 19th ed. / Ch 367Following a lesion of the hypoglossal nucleus or nerve* ATROPHY of the muscles of the IPSILATERAL one-half of the tongue occurs.* FASCICULATIONS (tiny, spontaneous contractions) can be seen.* Upon protrusion, the tongue will deviate TOWARD the side of the lesion (i.e.} same side). This is due to the unopposed action of the genioglossus muscle on the normally innervated side of the tongue (the genioglossus pulls the tongue forward).The corticobulbar input to the hypoglossal nucleus arises from motor cortex and is predominantly CROSSED. Thus, a lesion in motor cortex will result in deviation of the tongue toward the opposite side or CONTRALATERAL to the lesion. In contrast to the atrophy and fasciculations seen in lesions of the hypoglossal nucleus and nerve (lower motor neuron), NO such signs are present after lesions of the corticobulbar tract.
Tongue deviation to left on protrusion
Tongue deviation to right on protrusion
Nasal twang to voice
Scanning speech defects
Cranial Nerve Disorders