CorticalControl of Motor Activity- Corticospinal Tract

Question 1

List 3 Major Types of Movements

Answer 1

1) Reflexes
2) Automatic Postural Adjustments
3) Voluntary

Question 2

Define: Reflexes

Answer 2

Stereotyped responses to stimuli

Question 3

Characteristics of voluntary movements

Answer 3

1) Goal oriented
2) Internally generated
3) Improve with practice

Question 4

What is at the top of the motor hierarchy

Answer 4

cerebral cortex

Question 5

Which is the most important pathway for voluntary movement

Answer 5

The cerebrospinal tract

Question 6

How many neurons does the corticospinal tract have ?

Answer 6

1, the UMN. This projects to LMN in the ventral horn of all levels of the spinal cord

Question 7

What is the UMN route

Answer 7

Cerebral Cortez-> Corona radiata-> Internal Capsule (posterior limb) -> Crus cerbri -> Ventral Pons -> Medullary pyramid (Pyramidal decussation) -> Lateral funiculus

Question 8

What is the somatotopical organization of the primary motor cortex

Answer 8

The lower limbs are most medial, as you move laterally -> upper limbs, face, mouth, tongue

Question 9

What is the relevance of the MCA

Answer 9

The MCA is the blood supply to the lateral corticex, so it is responsible for both motor and sensory cortices.

A stroke in the upper MCA will affect the upper body.
A stroke in the lower MCA will affect the face and possibly cause aphasia.

Question 10

What is the relevance of the ACA

Answer 10

It supplies the medial humunculus. A stroke in the ACA wil affect the lower limbs

Question 11

Is the corona radiata somatotopically organized also ?

Answer 11

Yes

Question 12

Significance of the internal capsule

Answer 12

The Corona Radiata converges here. So if there is an insult here it will affect much more than a single diffuse area affected by an isolated injury in The Corona Radiata

Question 13

What track runs through the middle of the crus cerbri

Answer 13

The crus cerbri is located in the midbrain. The corticospinal tract runs through the middle of it.

Question 14

Where is the tectum

Answer 14

It is in the midbrain only. It is posterior to the cerebral aqueduct and the colliculi

Question 15

How close will the neurons of the cst be in the pons

Answer 15

They will be very broken up in the pons

Question 16

How will the CST look in the medulla

Answer 16

The tracts of the CST will be very consolidated in the medulla. They will decussate at the medullary pyramids

Question 17

Where does the CST travel once in the spinal cord ?

Answer 17

It travels in the lateral funiculus so the lateral spine.

Question 18

What is the somatotopy of the lateral funiculus

Answer 18

The axial muscles will be more medial and the distal muscles or extremities will be more lateral

Question 19

A lesion in the upper brainstem or internal capsule or the cortex will result in what type of lesion ?

Answer 19

A contralateral motor lesion

Question 20

A lesion in the spinal cord will result in what type of deficit

Answer 20

An ipsilateral lesion since the decussation already took place at the medullary pyramids

Question 21

What are some symptoms of injury to the lateral cortico-spinal tract ?

Answer 21

Loss of fractionated movement. So manual dexterity and precision will be gone

Question 22

Symptoms of UMN cortico-spinal tract ?

Answer 22

Contralateral paresis or paralysis
Spasticity
Hyperreflexia
Babinski sign
Clonus

Question 23

More symptoms of UMN lesion on one side

Answer 23

The unaffected side will try to move to compensate for teh loss in the injured side. For example unaffected wrist will attempt to move to compensate for affected wrist.

Question 24

A lesion in the midbrain is associated with what ?

Answer 24

Weber’s syndrome:

• Contralateral body deficits
• Ipsilateral eye deficits with movement, ptosis and abscent light reflex via EW

Question 25

A lesion in the pons is associated with what ?

Answer 25

Facial nerve deficits

Question 26

A lesion in the medulla is associated with what ?

Answer 26

medial medullary syndrome : Medial Lemniscus deficits
- Touch, vibration and proprioception deficits on contralateral side. There will be contalateral side paralysis and UMN lesion, hyperreflexia, and Babinski sign.