Motor Pathways II: Brainstem Systems

Question 1

Describe in detail the anatomy and function of the corticobulbar system

Answer 1

Voluntary control of:

• jaw movements
• muscles of facial expression
• swallowing and voice modulation
• tongue mobility

Question 2

Describe the anatomy of the GSE and SVE brainstem nuclei and their central connections, noting the rostrocaudal and transverse placement of nuclei and fiber bundles as they relate to previously learned brainstem and spinal cord structures

Question 3

Predict patterns of dysfunction associated with lesions to supranuclear (UMN) and nuclear (LMN) motor neurons in the brainstem

Answer 3

CN VI palsy
CN IV palsy
CN III palsy
CN XI palsy
LMN lesions to VII nucleus and nerve
UMN lesions to VII nucleus and nerve
Eight and a half syndrome

Question 4

Explain the mechanisms for horizontal gaze control in the brainstem and predict patterns of ocular motor dysfunction associated with lesions to different components of the system

Question 5

Explain how saccadic eye movements are generated, noting the cortical role and brainstem circuitry involved in initiation and maintenance of horizontal and vertical eccentric gaze

Question 6

Explain why horizontal saccadic gaze defects can be overcome with horizontal VOR, and why internuclear ophthalmoplegia can be overcome by vergence

Question 7

Describe the afferent and efferent limbs of the gag reflex and corneal blink reflex, and review the jaw-jerk reflex

Question 8

Explain the patterns of deficits associated with pseudobulbar palsy and locked-in syndrome