Motor Nuclei in brainstem

Question 1

Oculomotor nucleus

Answer 1

CN III

• superior colliculus
• lesion causes deficits in voluntary eye movement

*no corticobulbar (get from frontal eye field)

Question 2

Trochlear nucleus

Answer 2

CN IV

• inferior colliculus
• deficit in contralateral eye movement
• only nucleus that projects to contralateral side
• no corticobulbar (get from frontal eye field)

Question 3

Trigeminal motor nucleus

Answer 3

CN V

• middle pons
• deficits in mastication
• bilateral corticobulbar projections

Question 4

Abducens nucleus

Answer 4

CN VI

• caudal pons (fourth ventricle)
• deficit can’t abduct eye

*no corticobulbar (get from frontal eye field)

Question 5

Facial motor nucleus

Answer 5

• caudal pons
• deficit causes drooping of facial muscles
• contralateral corticobulbar projections for lower facial nucleus, bilateral for the rest

Question 6

Nucleus ambiguous

Answer 6

CN IX, X

• medulla
• deficit dysphagia, dysarthria
• bilateral corticobulbar projections

Question 7

Spinal accessory nucleus

Answer 7

CN XI

• cervical spine ventral horn
• shoulder drop, abduction problems
• bilateral corticobulbar projections

Question 8

Hypoglossal nucleus

Answer 8

CN XII

• medulla (fourth ventricle)
• one sided flaccid paralysis of tongue
• contralateral corticobulbar projections

*descending inputs arise from contralateral cortex

Question 9

Corticobulbar projections

Answer 9

• innervate SVE cell columns and the hypoglossal nucleus

- mediate voluntary movement