Motor pathways

Question 1

What is the somatotopic map rule, and what is the exception in major pathways? (2)

Answer 1

Rule: upper body medial, lower body lateral EXCEPT

1. Posterior columns: arms added on laterally as you go higher
2. Legs are medial in the cortex for motor and sensory

Question 2

What is the vessel that provides the major blood supply to the lumbar and sacral cord?
What area in the spine is the most vulnerable?

Answer 2

Great radicular artery of Adamkiewicz supples lumbar and sacral cord.
T4-T8 is vulnerable area (watershed)

Question 3

Name the major motor tract and key nuclei:

1. bilateral axial girdle muscles
2. head/neck position
3. balance
4. automatic posture and gait movements
5. coordination of eye/head movements

Answer 3

1. anterior CST
2. Vestibulospinal tracts: Medial VST
3. Vestibulospinal tracts: Lateral VST
4. Reticulospinal tracts: pontine and medullary reticular formation
5. Tectospinal tract: superior colliculus - dorsal tegmental midbrain decussation

Question 4

What is the positioning of face, arm, leg in the internal capsule?

Answer 4

Face is anterior

Arms and legs are posterior

Question 5

Position of corticobulbar and corticospinal fibers in basis pedunculi in midbrain? What part of the basis pedunculi and in what order?

Answer 5

In Basis pedunculi in midbrain, the fibers are in the middle 1/3 and from medial –> lateral: (medial) face –> arms –> legs (lateral)

Question 6

Parasympathetic cranial nerves?

Answer 6

3, 7, 9, 10

Question 7

Localization for hemiparesis / hemisensory loss of vib/jp, and opposite side tongue weakness?

Answer 7

Medial medullary lesion

Question 8

Localize: Brown-sequard plus decreased facial sensation

Answer 8

high cervical lesion with involvement of spinal trigeminal nucleus and tract

Question 9

localize gait ataxia

Answer 9

cerebellar vermis, midline cerebellum