Week 6 SDL: Contents of vertebral canal/ column

Question 1

In adulthood, why is the spinal cord much shorter than the length of the vertebral column?

Answer 1

during development, the vertebral column grows at a much faster rate

Question 2

At which level does the spinal cord end in newborns?

Answer 2

L3

Question 3

At which level does the spinal cord end in adults?

Answer 3

Between L1 and L2

Question 4

What is the conus medullaris?

Answer 4

the tapered end of the spinal cord from which a thin pial thread, the filum terminale, continues downwards to attach to the coccyx

Question 5

What is the cauda equina?

Answer 5

made up of lower lumbar, sacral and coccygeal nerve roots descending through the lumbar cistern i.e the region of the subarachnoid space between the level of termination of the cord and the level at which the dura and arachnoid coverings terminate (about S2)

Question 6

Where is the epidural space and what does it contain?

Answer 6

• space between the dura and vertebra. contains fat, veins, spinal arteries and lymphatics
• terminates at L1

Question 7

Which arteries supply the spinal cord?

Answer 7

1. ASA - originates from the vertebral artery and descends down to supply the anterior aspect of the spinal cord
2. 2 x PSA - originates from the vertebral artery and supplies the dorsal third of the spinal cord

Question 8

Which arteries reinforce the anterior and posterior spinal arteries?

Answer 8

radicular branches of the intercostal and lumbar arteries which enter the vertebral canal through the intervertebral foramina

Question 9

Explain the venous drainage of the spinal cord

Answer 9

1. anterior spinal vein (parallel to the anterior median fissure)
2. posterior spinal vein (parallel to the posterior median sulcus)
3. these drain into the internal vertebral plexus embedded in the epidural fat of the VC
4. at each vertebral level, there is drainage of the internal vertebral plexus into segmental thoracic, abdominal and intercostal veins and the external vertebral venous plexus to eventually connect with major systemic veins

Question 10

Do spinal nerves have valves

Answer 10

no

Question 11

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

Answer 11

• The dorsal root bears a dorsal root ganglion containing cell bodies of sensory neurones
• The ventral (or motor) root consists of axons from the LMNs in the ventral horn of the spinal cord

Question 12

What is the function of dorsal rami?

Answer 12

Dorsal branch of spinal nerves innervate skin of back, intrinsic muscles of the back and sympathetics to the skin

Question 13

What is the function of ventral rami?

Answer 13

innervates all muscles (except intrinsic back musckes) and cutaneous regions of the body. visceral pain

Question 14

How many spinal nerves are associated with each region?

Answer 14

cervical = 8 
thoracic = 12
lumbar = 5
sacral = 5 
coccygeal = 1 
= 31 pairs of spinal nerves

Question 15

In which clinical conditions is the composition of CSF altered?

Answer 15

• meningitis
• intracranial tumours
• subarachnoid haemorrhage
• cerebral infarction

Question 16

Starting with the skin, list the layers pierced by the lumbar puncture needle

Answer 16

• Skin
• Subcutaneous tissue
• Supraspinous ligament
• Interspinous ligament
• Ligamentum flavum
• Epidural space
• Dura
• Arachnoid
• Sub arachnoid space

Question 17

Moving the needle through which ligament causes a ‘pop’ during an LP?

Answer 17

Ligamentum flavum

Question 18

What are the signs and symptoms of sciatica?

Answer 18

• Lower back pain
• Numbness or tingling in shoulders, back, arms, hands, legs or feet
• Neck pain
• Problems bending or straightening your back
• Muscle weakness
• Pain in buttocks, hips or legs if the disc is pressing on the sciatic nerve

Question 19

Which region of the spinal cord has the most white matter and why?

Answer 19

cervical level because ascending and descending fibres from and to all levels must pass through the cervical cord

Question 20

In which sections is the dorsal white matter subdivided into two columns on each side? What type of information runs in these columns?

Answer 20

• Above T6
• Cuneate fascicle is responsible for transmitting vibration, proprioception, and fine (discriminative) touch sensations from upper body
• Gracile fasciculus carries sensory information from the lower half of the body entering the spinal cord at the lumbar level.
• The cuneate fasciculus carries sensory information from the upper half of the body, entering the spinal cord at the cervical level

Question 21

In which spinal cord segments in the ventral grey horn enlarged and why?

Answer 21

• in the cervical and lumbar segment

- due to the accumulation of motor neurones for innervation of the limbs

Question 22

Where are the lordosis on the back?

Answer 22

cervical and lumbar regions

Question 23

What are the distinguishing features of a cervical vertebrae?

Answer 23

bifid spinous process and foramina in the transverse process (there are no foramina in the thoracic and lumbar vertebrae)

Question 24

why does cervical vertebrae have transverse foramina?

Answer 24

The transverse foramina of the cervical vertebrae provide a passageway by which the vertebral artery, vein and sympathetic nerves can pass. The only exception to this is C7 - where the vertebral artery passes around the vertebra, instead of through the transverse foramen.

Question 25

What is the difference in the transverse processes in the thoracic and lumbar vertebrae?

Answer 25

The transverse processes are longer and bulkier in the thoracic spine but shorter and thinner in the lumbar vertebrae

Question 26

Describe the appearance of the spinous process in the thoracic vertebrae

Answer 26

long and angled obliquely and overlaps with the spinous process of the vertebrae below

Question 27

Which cervical vertebrae have much longer spinous processes?

Answer 27

C6 and C7

C7 = ‘vertebrae prominens’ –> prominent bone that we can palpate at back of neck

Question 28

How can you tell which aspect of the C1 vertebrae (‘the atlas’) is anterior?

Answer 28

the anterior arch is shorter - the posterior arch is the longer of the two

Question 29

What is the function of the transverse ligament of atlas?

Answer 29

maintains contact between the dens and the anterior arch of C1

Question 30

Where is the last functional intervertebral disc?

Answer 30

between L5 and S1

Question 31

What is the purpose of the anterior and posterior sacral foraminae?

Answer 31

anterior sacral foraminae - for exit of anterior rami of spinal nerves
posterior sacral foramina – for exit of posterior rami spinal nerves

Question 32

What are denticulate ligaments?

Answer 32

extensions of the pia matter - secure the cord laterally on either side

Question 33

Which region of the vertebral column is most flexible?

Answer 33

cervical –> the intervertebral discs are thicker at the C and L spine which makes these regions more flexible

Question 34

Which movement does the erector spinae muscle allow?

Answer 34

extension

Question 35

Which ligament of the VC is the only one that resists hyperextension?

Answer 35

anterior longitudinal

Question 36

Where is the ligamentum flavum found?

Answer 36

between adjacent transverse processes