C: Spinal cord and Spinal nerves

Question 1

What is the functional difference between the dorsal and ventral roots?

Answer 1

Dorsal - carries sensory afferent fibres

Ventral - carries motor efferent fibres

Question 2

Where do the dorsal and ventral roots unite to form spinal nerves?

Answer 2

In or near the intervertebral foramen

Question 3

What do the dorsal rami of spinal nerves supply?

Answer 3

Muscles and skin of the back region

Question 4

What do the ventral rami of spinal nerves supply?

Answer 4

Muscles and skin of the front of the body and the limbs

Question 5

Name 3 conditions in which the composition of CSF may be altered?

Answer 5

1) Meningitis
2) SAH
3) MS

Question 6

At what vertebral level does the spinal cord terminate in an adult?

Answer 6

L1

Question 7

At what vertebral level does the spinal cord terminate in a neonate?

Answer 7

L3 vertebral body

Question 8

What is the most common site from which CSF is sampled in adults?

Answer 8

Lumbar cistern

Question 9

What position is the patient in to perform a lumbar puncture?

Answer 9

Positioned on one side, perpendicular to the bed and curled up as much as possible, needle is inserted into the midline between the L3/L4 vertebra

Question 10

What surface landmarks would you use to determine the point at which to insert the needle in a lumbar puncture?

Answer 10

Spinous processes

Line between 2 iliac crests

Question 11

Why is the patient asked to curl up when taking a CSF sample?

Answer 11

Flex the vertebral column - spinous processes are more prominent for obtaining correct site
Intervertebral space is made larger

Question 12

Starting with the skin which layers are pierced by a lumbar puncture needle?

Answer 12

1) Skin
2) Subcutaneous tissue
3) Supraspinous ligament
4) Interspinous ligament
5) Ligamentum flavum
6) Epidural space
7) Dura
8) Arachnoid
9) Subarachnoid space

Question 13

In what way is bladder function affected by compression of the cauda equine eg. by a tumour?

Answer 13

Difficulty with micturition

Question 14

In a series of cross-sections taken from each region of the spinal cord, which section would contain the most white matter why?

Answer 14

Cervical - closest to the head, conveying more axons than any other region

Question 15

In which region of the spinal column is the dorsal white matter subdivided into 2 columns on each side?

Answer 15

Thoracic (above T6) and cervical

Question 16

What kind of info is carried in the cuneate and gracile fascicles?

Answer 16

Both discriminative touch, vibration and proprioception
Gracile - below T6
Cuneate - above T6

Question 17

In which spinal cord segments is the ventral grey horn enlarged due to the accumulation of motor neurons for innervation of the limbs?

Answer 17

Cervical (upper limb)

Lumbar (lower limbs)

Question 18

What types of sensory info are carried by the spinothalamic tract?

Answer 18

those essential to survival - pain, temperature, some touch and pressure

Question 19

Does the spinothalamic tract run ipsilaterally or contralaterally in the cord?

Answer 19

Contralaterally

Question 20

In which region of the cerebral cortex does the spinothalamic pathway terminate?

Answer 20

Post-central gyrus

Question 21

Where does the secondary sensory area for somaesthetic information lie?

Answer 21

Superior parietal lobe - posterior to post-central gyrus

Question 22

What types of sensory info are carried in the dorsal column pathway?

Answer 22

2 point discriminative touch, vibrations and proprioception

Question 23

Where do the fibres of the dorsal column pathway run at the level of the spinal cord?

Answer 23

Ipsilaterally

Question 24

Where do the fibres of the dorsal column pathway run at the level of the closed medulla?

Answer 24

Ipsilaterally (cross at the level of the closed medulla)

Question 25

Where do the fibres of the dorsal column pathway run at the level of the open medulla?

Answer 25

Contralaterally

Question 26

What determines whether fibres ascend in the gracile or cuneate fascicle?

Answer 26

Gracile - from below T6

Cuneate - from above T6