Lecture 8: Desc. Motor systems

Question 1

The CST originates in the…

Answer 1

Cerebral cortex, pre central gyrus and nearby areas

Question 2

The CST descends through the…. of rostral midbrain, the …. of the rostral pons, the…of the caudal medulla and decussates at the….

Answer 2

• cerebral peduncle
• basis points
• medullary pyramid
• spinomedullary junction

Question 3

CST has 3 types of fibers
80%…
10%…
10%…

Answer 3

1. Lateral CST that cross
2. Lateral CST that don’t cross
3. Anterior CST that don’t cross and descend in anterior faniculus

Question 4

Anterior CST fibers that do not cross and descend in the anterior faniculus are for…. activity

Answer 4

axial muscle activity, some actually cross in anterior commissure prior to synapsing

Question 5

Action of type 1 muscles

Answer 5

sustained force/weight bearing (turkey leg) slow twitch

Question 6

Type 1 muscles: amount of lipids, glycogen and mitochondria

Answer 6

lipids- abundant
glycogen- scant
mitochondria- many

Question 7

Action of type 2 muscles

Answer 7

sudden movements, purposeful motion (turkey breast) fast twitch

Question 8

Type 2 muscles: amount of glycogen, lipids and mitochondria

Answer 8

lipids- abundant
glycogen- scant
mitochondria- few