Pyramidal systems

Question 1

Pyramidal system

Answer 1

The basic system; Motor cortex -> spinal cord -> AMN

Dorsolateral system, needed for distal, fine movement and tonus.

• Conscious, voluntary control of skeletal muscles
• Starts at upper motor neurons (PMC, SMA)
• Axons descend into brain stem and spinal cord
• Two tracts; bulbar and spinal

Question 2

Corticobulbar

Answer 2

Towards cranial nerve nuclei that move eye, jaw, face and some muscles of the neck and throat

Question 3

Cotricospinal tract

Answer 3

Visible along ventral surface of the medulla as two thick bands: the pyramids.
- Control of all non-facial somatic muscles
- Lateral CS Tract crosses at the parymidal decussationat high level
- Anterior CS tract cross to opposite side of spinal cord at lower level in anterior white commissure

Question 4

Pyramidal decussation

Answer 4

Crossover, you can see it in the brain (sort of knick)

Question 5

Damage to corticospinal tract

Answer 5

Paralysis/paresis (typically)

Typically, you find a pattern of weakness in the extensors in the upper limbs, or flexors in the lower limbs. This is known as pyramidal weakness.

Question 6

Babinski sign

Answer 6

Diagnostic of lesion in corticospinal tract. Normal respons (curling down) of the toes doesn’t occur, instead they fan out.