Corticospinal Tract

Front 1

1. What is the major descending motor pathway carrying voluntary impulses from the brain to your skeletal m?
2. what does it innervate?
3. What does the corticobulbar tract innervate?
4. How many neuron are in these systems?

Back 1

1. Corticospinal tract
2. all voluntary m. of the body that are controlled by spinal n and their branches- maintains normal m. tone and reflexes
3. voluntary m. innervated by CN
4. 2

Front 2

1. Where does the corticospinal tract originate? (Brodman's area?)
2. What is the name for the 1st order neurons?
3. What is the name for the 2nd order neurons?

Back 2

1. Cerebral cortex in the precentral gyrus (4)
2. Upper motor neurons (UMN)
3. Lower motor neurons (LMN)

Front 3

Corticospinal:
1. Location of the LMN?
2. What are located between the UMN & LMN>?
3. Other pathways mediate voluntary movements, but what does corticospinal play biggest role in?

Back 3

1. Ventral horn (location of 1st synapse)
2. Interneurons
3. speed and agility to voluntary m. (rapid skilled movements, particularly for extensor of UE and flexors of the LE) (other pathways have simpler basic voluntary movement)

Front 4

1. Small collaterals come off the corticospinal tract and send info to other parts of the brain. What does it send info through?
2. Where do the pyramid of the corticospinal tract decussate?

Back 4

1. Reticular formation
2. In the caudal medulla

Front 5

1. Describe the UMN corticospinal tract pathway

Back 5

1. pre central gyrus -> descend through the corona radiata and posterior limb of internal capsule -> UMN fibers enter midbrain through middle 3/5 of cerebral peduncles -> UMN fibers descend through the pons and into the medulla where they form pyramids -> pyramids decussate in the caudal medulla -> pyramids form the lateral corticospinal tract which descends through the spinal cord to each spinal level, and interneurons leave the tract to synapse in the ventral horn

Front 6

1. Describe the LMN corticospinal tract pathway

Back 6

LMN fibers originate in the ventral horn of the spinal cord -> LMN fibers leave the spinal cord on the ventral roots -> ventral roots join dorsal roots to form spinal nerves -> spinal n. for peripheral n and travel to respective m.

Front 7

1. What is the motor humunculus like?
2. Where do upper motor neurons arise from?
3. What is the blood supply like for the corticospinal tract?

Back 7

1. same as sensory with LE in the upper midline, then ascending as you move medially
2. Pyramidal shaped Betz cells (pyramids of medulla)
3. Same as for sensory w/ MCA, ACA, anterior spinal a., and pontine a. but the Posterior inferior spinal a. plays a role in providing nutrition to the lateral corticospinal tract in the brain stem

Front 8

1. Initial lesion of the spinal cord leads to a period of what? (What happens next)
2. Clasp knife reflex is indicative of what?
3. Term for repetitive, rhythmic contractions of flexor mm when distal limb joint is quickly moved and held in extension

Back 8

1. spinal shock- yields a flaccid paralysis from the level of the lesion and inferiorly (spastic paralysis- m. tone and reflexes return but in a hyperactive state)
2. Hypertonia
3. Clonus

Front 9

1. Continued paralysis, hyperreflexia, clonus, hypertonia (clasp knife reflex), and + Babinski signs are sx of what?
2. Plegia is what? (due to what?)
3. Hemiplegia (monoplegia)
4. paraplegia (quadriplegia)

Back 9

1. Spastic paralysis
2. paralysis (ablative lesion)
3. paralysis of half the body on 1 side (paralysis of 1 extremity)
4. paralysis of both extremities (paralysis of all 4 extermities)

Front 10

1. Paresis is? (due to what)
2. Hemiparesis (quadraparesis)

Back 10

1. Weakness (irritative lesion)
2. Weakness of 1/2 of body (weakness of all 4 extremities)

Front 11

1. Signs of an UMN lesion?
2. Signs of a LMN lesion?

Back 11

1. Paralysis, hyperreflexia, hypertonia, clonus, Babinski sign
2. Paralysis, normal or decreased reflexes, hypotonia, fasciculation, atrophy

Front 12

Movement – Strength Scale
5 Normal
4 Moves against moderate resistance
3 Movement against gravity only with no resistance
2 Movement but not completely against gravity
1 Muscular contraction but no movement
0 No movement

Back 12

Reflexes Scale
4 Clonus
3 Brisk reflexes (may be normal or mildly pathologic)
2 Normal
1 Sluggish (often present only with reinforcement)
0 Absent reflexes

Front 13

1. How can reflexes be reinforced and increased?
2. Lesion of the corticospinal tract ABOVE decussation does what?
3. Lesion of the Corti. below decussation?
4. Pyramidal weakness?

Back 13

1. clenching teeth or the Jendrassick maneuver (hooking finger together and pulling hard)- causes additional excitation to the alpha motor neurons
2. Contra spastic hemiplegia
3. Ispilateral hemiplegia at that level and inferiorly
4. Weakness of extensors of UE and flexors of LE

Front 14

1. What does LMN lesions do?

Back 14

1. Ispilateral flaccid paralysis w/ atrophy to the m.