Motor Control 2 - Corticobulbar Tract

Question 1

Describe the course of the CBT

Answer 1

2 neurone pathway

UMN leaves primary motor cortex (pre central gyrus) and passes through the genu of the internal capsule between the thalamus and the basal ganglia

Synapses with lower motor neurone in the nuclei of the cranial nerves in the brainstem

Question 2

Which cranial nerves connect bilaterally and which do not

Answer 2

All motor nerves connect bilaterally minus facial nerve and hypoglossal

Question 3

A lesion to upper motor neurones on a bilateral cranial nerve would cause what?

Answer 3

Pseudobulbar palsy

Mild forms of weakness in the affected muscles

Question 4

An UMN lesion to the facial nerve will cause what? Why?

Answer 4

Contralateral paralysis of the lower face with sparing of contralateral upper face

Due to lower nucleus of facial nerve receiving only contralateral innervation from UMN, resulting in lower contralateral facial impairment

Upper face spared / pseudobulbar palsy due to bilateral upper nuclei innervation

Question 5

Lower motor neurone lesion in facial nerve causes what?

Answer 5

Contralateral paralysis of upper and lower face due to lower neurones innervating the muscles are affected.

Question 6

What would an UMN lesion of the hypoglossal nerve cause?

Answer 6

Contralateral paralysis of tongue muscles

When tongue stuck out, would deviate to the opposite side

E.g right UMN lesion, left muscles dont work so tongue would stick out and left