Neuro 2: Spinal Cord function and Dysfunction

Question 1

How many spinal segments are there?

Answer 1

31

Question 2

What does the 31 pairs of spinal nerves consist of?

\_\_\_ cervical 
\_\_\_ thoracic 
\_\_\_ lumbar 
\_\_\_ sacral 
\_\_\_ coccygeal

Answer 2

What does the 31 pairs of spinal nerves consist of?

8 cervical 
12 thoracic 
5 lumbar 
5 sacral 
1 coccygeal

Question 3

Nerves leave the vertebral column through the _______ ______

Answer 3

Nerves leave the vertebral column through the INTERVERTEBRAL FORAMINA

Question 4

Where are the 2 enlargements for the innervation of the limbs?

Answer 4

Cervical (C3-T1)
- has extra motor neurones that goes to muscles of the upper limb

Lumbar (L1-S3)
- has extra motor neurones that goes to the muscles of the lower limb

Question 5

Lesion of nerve above C3-C5 would result in

Answer 5

Lesion of nerve above C3-C5 would result in :

- not being able to breathe

Question 6

What is a major difference in the development of the spinal cord and the vertebral column?

Answer 6

• spinal cord stops growing early

- vertebral column keep on growing into adulthood.

Question 7

What part can be used to sample CSF ?

Answer 7

• the lumbar cistern

Question 8

What are the 3 layers of meninges?

Answer 8

What are the 3 layers of meninges?

• subarachnoid space
• pia mater (denticulate ligaments)
• extradural/epidural space

Question 9

What is in the subarachnoid space?

Answer 9

CSF

Question 10

What is the function of the denticulate ligaments?

Answer 10

• tethers the spinal cord

- holds it in the middle of the subarachnoid space

Question 11

Where is extradural/epidural space located in?

would you find this in the cranial meninges?

Answer 11

• between outside of the dura + the bone

no.

Question 12

What is epidural space fulled with ?

Answer 12

venous plexuses + fatty tissue

Question 13

why is the epidural space clinically useful?

Answer 13

clinically useful:

because you can inject anesthetic by giving an epidural

Question 14

What are the 3 most important tracts in spinal cord injury?

Answer 14

1. Lateral Corticospinal Tract
   - motor
   - for fine movements
2. Dorsal Columns
   - sensory
   - touch, vibration, pressure
3. Spinothalamamic Tract
   - pain, temp

Question 15

What are the 2 stages of response to an injury to the lateral corticospinal tract?

Answer 15

STAGE 1 - spinal shock:

STAGE 2 - Return of reflexes:

Question 16

Describe stage 1 response to injury to the lateral corticospinal tract

Answer 16

STAGE 1 - spinal shock: 
- lose all reflex activity below level of lesion 
- no direct damage (just stops working) 
- leads to flaccid paralysis 
(limbs = floppy, little muscle tone)

Question 17

Describe stage 2 response to injury to the lateral corticospinal tract

Answer 17

STAGE 2 - Return of reflexes:
- hyperreflexia
(if you test knee jerk reflex, legs will go mad)
- spasticity occurs
(spontaneous muscle contraction occurs)
- there is very high muscle tone –> rigid paralysis

most probably due to lower motor neurons below level of lesion being cut off from their normal activating pathway

• -> so they have lowered threshold
• -> becomes more sensitive.

Question 18

Lateral corticospinal tract neurones decussate at level of ______

Answer 18

Lateral corticospinal tract neurones decussate at level of the medulla

Question 19

Unilateral lesion in mid thoracic region –> deficit is on same/opposite side as lesion

Answer 19

Unilateral lesion in mid thoracic region –> deficit is on same side as lesion

Question 20

What is the Dorsal Column responsible for?

Answer 20

Dorsal Column responsible for:

- fine touch + proprioception

Question 21

Describe the tract/organisation of the dorsal column

Answer 21

• sensory neurons enter the spinal cord
• they travel up same side of spinal cord
• also decussates at level of the medulla
• then goes to the somatosensory cortex

Question 22

What is the Spinothalamic tract responsible for?

Answer 22

• pain and temperature

Question 23

Describe the tract/organisation of the spinothalamic tract

Answer 23

• pain nerves cross over immediately as they enter spinal cord
• neurons goes into dorsal horn
• synapses with 2nd cell
• which sends its axon immediately across the midline

Question 24

Left sided unilateral lesion at mid thoracic level doesn’t interrupt the spinothalamic tract from the ____leg

BUT
it will interrupt the spinothalamic tract going up the ____ side coming from the ___ leg

So lesion on the left causes loss of pain sensation in the ____ leg

Answer 24

Left sided unilateral lesion at mid thoracic level doesn’t interrupt the spinothalamic tract from the LEFT leg

BUT
it will interrupt the spinothalamic tract going up the LEFT side coming from the RIGHT leg

So lesion on the left causes loss of pain sensation in the RIGHT leg

Question 25

List 3 factors affecting severity of spinal lesion

Answer 25

1. loss of neural tissue 2. vertical level 3. transverse plane

Question 26

Explain how loss of neural tissue affects severity of spinal lesion

Answer 26

usually trauma --> loss of neural tissue = small metasases, degenerative diseases --> more extensive loss

Question 27

Describe how vertical level affects severity of spinal lesion

Answer 27

higher the lesion, greater the disability

Question 28

What is the most common cause of spinal cord injury?

Answer 28

- broken neck or back

Question 29

What are the 3 tracts important for spinal cord injury?

Answer 29

- lateral corticospinal tract - dorsal columns - spnothalamic tract

Question 30

Describe the Brown-Seuard syndrome

Answer 30

- with unilateral lesions, the relationship of the deficit to the lesion depends on where the tract decussates.

Question 31

note: at top vertebral level +spinal cord segment = correlates at bottom there is greater discrepancy btw spinal + vertebral levels --> place where spinal nerve emerges becomes more and more inferior in relation to the vertebral level

Answer 31

-

Question 32

collection of nerves at bottom =

Answer 32

chordae equina

Question 33

there are _ cervical vertebrae but ___ cervial nerves

Answer 33

there are 7 cervical vertebrae but 8 cervial nerves

Question 34

note: there is no epidural space in the brain, but there is a epidural space in the spinal cord

Answer 34

-

Question 35

why are the presence of meninges important?

Answer 35

- for reabsorption of CSF | - for protection

Question 36

What is the difference between dermatome / myotomes?

Answer 36

area of skin(dermatome) or muscle (Myotome) innervated by one single spinal nerve/ segment

Question 37

note: motor neurones goes into ventral horn - (anterior horn) (upper butterfly wing) sensory neurons goes into dorsal horn (posterior horn) (lower butterfly wing) but in the RAMUS of both - there is a mixture of sensory + motor

Answer 37

-

Question 38

Describe the pathway of the corticospinal tract

Answer 38

- voluntary movement starts in motor cortex - there is a single neurone in the brain which synapses onto the a single neurone in the ventral horn then a peripheral nerve goes out to a muscle - upper motor neurone = in brain - it emerges and crosses over in the medulla at the decussation of the pyramids --> and travels down the spinal cord --> becomes a part of peripheral nerve --> then goes to a muscle

Question 39

3 main sensory neurones located at:

Answer 39

- in skin - in cns - one going up to the brain

Question 40

sensory neurone has cell body in the ____ ___ ______

Answer 40

dorsal root ganglion

Question 41

What does the dorsal column pathway do?

Answer 41

it bring in information about fine touch --> activates dorsal column - sensory neurone strive up same side of spinal cord as the part of the body innervated