CN VII Flashcards
Describe the facial motor nucleus and the internal genu.
The facial motor nucleus is located within the pons inferior and lateral to the abducens nucleus. LMN axons from this nucleus will wrap around the abducens nucleus forming the internal genu.
What is clinically significant about the internal genu?
lesions affecting the abducens nucleus can commonly effect ipsilateral facial muscles.
Where are cell bodies of GVE-P carried by VII found?
Superior salivatory nucleus, which is just inferior and lateral to the facial motor nucleus.
Where do the cell bodies of primary afferents conducting GVA and SVA of VII lie and where do they project to?
Cell bodies lie in the geniculate ganglion near the external genu. These primary afferents synapse on to second order neurons at the solitary tract.
Describe the innervation by corticobulbar tracts of lower motor neurons in the facial motor nucleus.
UMNs in BA 4 project to the facial motor nucleus in different patterns depending if it is the upper or lower portion of the motor nucleus they innervate. Corticobulbar fibers project bilaterally to the upper portion of the facial motor nucleus, which houses LMNs that innervate the upper face. Corticobulbar fibers project contralaterally to the lower portion of the facial motor nucleus, whcih houses LMNs that innervate the lower face.
Describe supranuclear palsy and its presentation.
Supranuclear palsy would be due to a one-sided lesion of the corticobulbar fibers innervating the facial motor nucleus. This would present with palsy of the lower contralateral face due to the patterns of innervation.
Why are patients with supranuclear palsy able to smile spontaneously?
Individuals with supranuclear palsy may still smile spontaneously in response to emotional stimuli because facial expression in response to emotion is controlled by a different pathway which probably involves the reticular formation, and possibly basal nuclei.
