The Spinal Cord

Question 1

What is the spinal cord?

Answer 1

Part of the CNS - the major reflex centre.
Begins at the medulla oblongata.
Ends at L1/L2.
The same length as the vertebral canal in 12wk old foetuses.

Question 2

What are the conus medullaris, cauda equina, and filum terminale?

Answer 2

Conus medullaris - conical inferior end.
Cauda equina - a bundle of nerve roots that exit out of intervertebral foramen at the end.
Filum terminale - continuation of pia mater.

Question 3

What are the lumbar cistern and dural sac?

Answer 3

Lumbar cistern - a dilated dural sac that ends at S2, and attaches to the tip of the coccyx by the filum terminale external.
Dural sac - the membranous sheath of dura mater that surround the spinal cord and cauda equina.

Question 4

What are the spinal nerves?

Answer 4

31 pairs that arise from the spinal cord.
Ventral rami of spinal nerves form nerve plexuses.
Made of sensory and motor fibres.

Question 5

What is the sympathetic and parasympathetic outflow of the spinal cord?

Answer 5

Sympathetic - thoracolumbar (T1-L2).
Cells bodies - the lateral horn of grey matter.

Parasympathetic - craniosacral.
Cranial nerves - 3, 7, 9, 10.
Pelvic splanchnic nerves - S2-S4.

Question 6

What is ischaemia in the spinal cord?

Answer 6

Spinal and segmental medullary artery branches are damaged, causing a deficiency of blood supply to the spinal cord.
Muscle weakness, paralysis, and venous drainage occur.

Question 7

What is venous drainage of the spinal cord?

Answer 7

Internal vertebral venous plexuses drain to the cerebral Dural venous sinuses.
Infection and cancer can spread to the CNS from other parts of the body.

Question 8

What are examples of spinal cord injuries?

Answer 8

Blunt trauma.
Penetrating injuries.
A herniated disc.
Bone metastasis (cancer, canal stenosis).

Causes a loss of motor function, sensation, and autonomic function.

Question 9

What is a lumbar puncture?

Answer 9

L3-L4 in adults; L4-L5 in children.
Injection for epidural anaesthesia.
Sampling CSF from the subarachnoid space.
The lumbar spine is flexed, to increase the space between spinous processes.

Question 10

How can injury occur in the different sections of the spine?

Answer 10

Cervical - canal is large enough to escape injury. If the cord is sectioned here, death occurs. If cut above C5, respiration ceases.
Thoracic - small canal, cord can be displaced.
Lumbar - large canal, nerve injury is minimal.