Corticospinal Tract & Other Motor Pathways

Question 1

3 Main Motor and Sensory “Long Tracts”

Answer 1

1. Lateral corticospinal tract - motor
2. Posterior columns - Sensory (vibration, joint position, fine touch)
3. Anterolateral pathways - Sensory (pain, temperature, crude touch)

Question 2

Funiculi

Answer 2

Ascending and descending white matter columns

Question 3

Dorsal root ganglion

Answer 3

Where sensory neurons bifurcate

1. One branch conveys info from the periphery
2. One branch carries sensory info through dorsal nerve root filaments into dorsal aspect of spinal cord

Question 4

Dorsal (posterior) horn

Answer 4

Involved mainly in sensory processing

Question 5

Intermediate zone

Answer 5

• in the gray matter
• contains interneurons and certain specialized nuclei

Question 6

Ventral (anterior) horn

Answer 6

Contains motor neurons

Question 7

3 parts of spinal cord white matter

Answer 7

1. Dorsal (posterior) columns
2. Lateral columns
3. Ventral (anterior) colums

Question 8

Lateral Corticospinal Tract

Answer 8

• most clinically important descending motor pathway
• controls movement of the extremities
• pathway:

1. >50% originate from primary motor cortex; remainder from premotor and supplementary motor
2. Axons travel through corona radiata (fanlike structure)
3. Goes through posterior limb of internal capsule

Question 9

Basis Pedunculi

Answer 9

• White matter located in the ventral portion of the cerebral peduncles in the midbrain
• middle 1/3 contains corticobulbar and corticospinal fibers
• face, arm, and leg axons arranged medial to lateral, respectively

Question 10

Pyramidal Decussation

Answer 10

• where 85% of corticospinal tract fibers cross over to the other side to enter lateral white matter columns forming the lateral corticospinal tract

Question 11

Anterior Corticospinal Tract

Answer 11

• the remaining 15% of fibers that do not decussate in the pyramid and travel in the ventral white matter column of the spinal cord