Spinal Cord Anatomy

Question 1

Describe 5 things about the spinal cord

Answer 1

1. Continuous with brainstem
2. Has a cone shaped termination (conus medullaris)
3. Filum terminale extends from the conus medullaris to the coccyx.
4. The caudal 1/3 is called the cauda equina.
5. Has two enlargements, cervical (C5-T1) and lumbosacral (L3-S2)

Question 2

What is the danger of trauma to the cauda equina?

Answer 2

May disrupt bowel and bladder function in addition to producing sensory deficits

Question 3

What is in the epidural space?

Answer 3

Fat and dural venous sinus

Question 4

Discuss the pia mater

Answer 4

Intimately attached to brain and spinal cord. Short extensions of pia called denticulate ligaments attach to the arachnoid and suspend the spinal cord in the vertebral canal.

Question 5

Where is a lumbar puncture performed?

Answer 5

In the lumber cistern.

Question 6

Describe the formation of spinal nerves

Answer 6

1. Dorsal and ventral roots form a spinal nerve.
2. Passes through the IVF
3. Divides immediately into anterior and posterior rami.

Question 7

What is a dermatome?

Answer 7

A strip of skin that is innervated by peripheral cutaneous branches of a spinal nerve.

Question 8

How does one lose sensation in a dermatome?

Answer 8

Three adjacent dorsal roots must be damaged.

Question 9

Discuss shingles

Answer 9

A viral infection of sensory nerve producing painful skin irritations that show a dermatomal distribution

Question 10

Describe the overall internal layout of the spinal cord

Answer 10

1. Butterfly shaped core of gray matter consisting of neuron cell bodies and dendrites.
2. Surrounded by white matter consisting of myelinated axon.

Question 11

Discuss Gray matter

Answer 11

Dorsal horn: Sensory
Intermediate zone: Sensory, Motor and preganglionic autonomic neurons.
Ventral horn: Motor

Question 12

Discuss White matter

Answer 12

Contains eight grooves, anteromedian fissure, posteromedian sulcus, anterolateral, posterolateral and posterior intermediate sulci. These regions are for long distance, bi-directional information flow between the spinal cord and higher CNS regions

Question 13

What is the danger to interuption of nerve conduction in the white matter?

Answer 13

Produces paralysis, loss of sensory and autonomic function.

Question 14

Describe the blood supply of the Gray and White matter

Answer 14

1. Main supply comes from the anterior and posterior spinal arteries.
2. Spinal medullary arteries perfused lumbar enlargement.
3. White matter supplied by vasocorona (branch of anterior and posterior spinal arteries)
4. Central branches of anterior spinal artery supply gray matter.

Question 15

What is the risk of an infarct to the anterior spinal artery?

Answer 15

Damages gray matter, impairing pain and temperature sensation. Also produces muscle weakness/paralysis

Question 16

Discuss the sensory input of the spinal cord

Answer 16

Primary sensory axons enter the spinal cord at the dorsal root entry zone and rearrange into two bundles: a medial division that contains rapidly conducting, myelinated fibers which ascend the dorsal columns and terminate in the brainstem and a lateral division containing slowly conducting, unmyelinated fibers which enter Lissauer’s tract located just below the posterolateral sulcus

Question 17

Discuss the specialization of spinal cord gray matter structure

Answer 17

There is an expansion of the dorsal and ventral horns in the cervical and lumbosacral enlargement because of the sensory and motor output from the limbs.

Question 18

Discuss the specialization of spinal cord white matter structure

Answer 18

White matter is most abundant in the cervical cord because it contains fibers going to and from all spinal cord levels.