Spinal Cord

Question 1

Dorsal column medial lemniscus (DCML) function.

Answer 1

Ascending sensory tract

Fine touch, conscious proprioception

Question 2

Corticospinal tract function.

Answer 2

Descending motor tract

Controls body muscles

Question 3

Spinothalamic tract function.

Answer 3

Ascending sensory tract

Pain, temperature, pressure

Question 4

What is the difference between the pyramidal and extrapyramidal motor tracts structurally and functionally?

Answer 4

Structurally: pyramidal tracts pass through the pyramids of the medulla and extra-pyramidal don’t

Functionally: pyramidal control conscious movement, extrapyramidal control unconscious movement

Question 5

Where does the dorsal column medial lemniscus (DCML) tract cross the midline?

Answer 5

Cross in the medulla

Question 6

Where does the spinothalamic tract cross the midline?

Answer 6

Segmentally

Question 7

Where does the corticospinal tract cross the midline?

Answer 7

Decussation of the pryamids in the medulla

Question 8

What spinal cord tract crosses

• segmentally
• in the medulla
• at the decussation of the pyramids

Answer 8

Segmental: spinothalamic

Medulla: dorsal column medial lemniscus

Decussation: corticospinal

Question 9

Describe the dorsal column medial lemiscus pathway.

Answer 9

First order neurons carry sensory information from the skin to the medulla

Second order neurons carry information from the medulla across the midline the the thalamus

Third order neurons carry information from the thalamus to the somatosensory cortex

Question 10

In the _______ tract, what is the name of the area which carries information from the upper limb and the lower limb?

Answer 10

Dorsal column medial lemniscus (DCML)

Upper limb: fasciculus cuneatus

Lower limb: fasciculus gracilis

Question 11

Which is medial and which is lateral?

Fasciculus cuneatus
Fasciculus gracilis

Answer 11

Fasciculus cuteatus: lateral

Faciculus gracilis: medial

Question 12

Describe the spinothalamic tract pathway.

Answer 12

First order neurons carry sensory information from the skin to the dorsal horn of the spinal cord

Second order neurons carry information from the dorsal horn across the midline to the the thalamus

Third order neurons carry information from the thalamus to the somatosensory cortec

Question 13

Where is the somatosensory cortex?

Answer 13

Postcentral gyrus

Question 14

Describe the corticospinal tract pathway.

Answer 14

Upper motor neurons cross the midline at the decussation of the pyramids and carry information from the motor cortex to the anterior horn of the spinal cord

Lower motor neurons carry information from the anterior horn of the spinal cord to the muscles

Question 15

What happens to

• tone
• muscle wasting
• fasciculation
• reflexes
• plantar reflex
• clonus

in UMN injuries?

Answer 15

Tone: increased
Muscle wasting: none
Faciculation: none
Reflexes: increased
Plantar reflex: up-going
Clonus: present

Question 16

What happens to

• tone
• muscle wasting
• fasciculation
• reflexes
• plantar reflex
• clonus

in LMN injuries?

Answer 16

Tone: reduced
Muscle wasting: present
Faciculation: present
Reflexes: reduced
Plantar reflex: down-going
Clonus: none

Question 17

If there are upper motor neuron signs, where must the lesion be?

Answer 17

Above the anterior horn of the spinal cord

spinal cord, brainstem, motor cortex

Question 18

If there are lower motor neuron signs, where must the lesion be?

Answer 18

In the anterior horn or distal to anterior horn

anterior horn, spinal nerve

Question 19

What causes upper motor neuron signs?

Answer 19

Loss of muscle inhibition from brain

Question 20

What are fasciculations?

Answer 20

Twitches

Question 21

What is clonus?

Answer 21

Involuntary, rhythmic, muscular contraction and relaxation

Question 22

What is posturing and what does it indicate?

Answer 22

involuntary flexion/extension of limbs

brain injury

Question 23

What are the two types of posturing?

Answer 23

Decorticate

Decerebrate

Question 24

What occurs in decorticate posturing and what part of the brain is injured?

Answer 24

Arms flexed, legs extended

Cerebral hemispheres

Question 25

What occurs in decerebrate posturing and what part of the brain is injured?

Answer 25

Arms extended, legs extended

Brainstem

Question 26

What causes Brown-Sequard syndrome?

How does it present? Explain why.

Answer 26

Hemisection of the spinal cord

Ipsilateral paralysis

• corticospinal tract damage
• ipsilateral as it crosses the midline at the pyramids before reaching the spinal cord (left hemisection disrupts information for the left side of the body = ipsilateral)

Ipsilateral loss of proprioception and fine touch

• DCML damage
• ipsilateral as it crosses the midline in the medulla after travelling through the spinal cord (information from the left hand side of the body is disrupted by a left hemisection = ipsilateral)

Contralateral loss of pain and temperature

• damage to spinothalamic tract
• contralateral as it crosses as it enters the spinal cord and before ascending. it crosses and then ascends, where it would meet a hemisection (sensation from the left is disrupted by a hemisection on the right = contralateral)

Question 27

A ____ spinal cord lesion would cause:

a) UMN signs
b) LMN signs

Answer 27

a) central

b) lateral

Question 28

Disease progression of cervical myelopathy.

Answer 28

1. Clumsy hands
2. Loss of fine function of hans
3. Loss of gross motor function of hands
4. Impaired mobility

Question 29

What is cervical myelopathy?

Answer 29

Central disc prolapse in the cervical spine