Spinal Cord

Question 1

List some functions of the spinal cord

Answer 1

• Receives primary afferent fibres from preipheral receptors in widespread somatic and visceral structures.
• Sends motor axons to skeletal muscle.
• Provides communications highway between the brain and the periphery.
• Houses preganglionic neurons of the sympathetic NS.
• Houses some preganglionic neurons of the parasympathetic NS.

Question 2

Describe where the spinal cord arises and terminates

Answer 2

The spinal cord is continuous with the medulla at a site just below the foramen magnum and terminates in a tapered cone-shape called the conus medularis.

This structure continues as a thin connective tissue cord called the filum terminale which is anchored to the dorsum of the coccyx.

Question 3

What comprises the cauda equina?

Answer 3

Below L1, the dural spinal canal only includes the dorsal and ventral roots of the L2 and lower spinal nerves and the filum terminale. This collection of roots is the cauda equina.

Question 4

At what vertebral level does the dural sac end?

Answer 4

~S2

Question 5

What happens to dorsal and ventral roots destined for spinal levels below L2 and the filum teminale?

Answer 5

They pass out of the dural sac.

They remain ensheathed by dura and travel in the spinal cord, but are no longer in the CSF of the subarachnoid space.

Question 6

Which structure suspends the spinal cord in the spinal canal?

Answer 6

A ribbon of tissue on the lateral aspect of the cord called the denticulate ligament.

This ligament is formed of pial and arahnoid tissue and attaches to the dura at points along the length of the cord.

Question 7

Where do the dorsal and ventral roots come together to form the spinal nerve?

Answer 7

In the vertebral canal.

They are accompanied by dura and arachnoid mater and these merge with the connective tissue coverings found around the nerve.

Question 8

What is the white matter in the spinal cord comprised of?

Answer 8

• Longitudinally orientated axons
• Glial cells
• Blood vessels

Question 9

Describe the central canal

Answer 9

• Extends the length of the spinal cord
• Caudally it is blind-ending
• Rostrally it traverses the caudal part of the medulla and opens into the 4th ventricle

Question 10

What is the grey matter in the spinal cord comprised of?

Answer 10

• Neuronal soma
• Cell processes
• Synapses
• Glia
• Blood vessels

Question 11

Where in the spinal cord is proportion of grey matter highest?

Answer 11

Cervical and lumbar enlargements

Question 12

Where is the proportion of white matter highest in the spinal cord?

Answer 12

Proportion of white matter is greatest in the cervical region and is progressively less at more caudal levels.

Question 13

At which spinal levels is there an intermediolateral cell column?

What does it contain?

Answer 13

T1-L2

Contains preganglionic sympathetic neurons.

Question 14

What are the three groups of major arteries which supply the spinal cord?

Answer 14

1. Longitudinal arteries
2. Segmental arteries
3. Radicular arteries

Question 15

Describe the longitudinal arteries which supply the spinal cord

Answer 15

Thee major longitudinal arteries:

• One anterior
• Two posterior
• Originate from the vertebral arteries and run the length of the cord.

Question 16

Describe the segmental arteries which supply the spinal cord

Answer 16

Derived from arteries:

• Vertebral
• Deep cervical
• Intercostal
• Lumbar

Question 17

Describe the redicular arteries which supply the spinal cord

Answer 17

• Travel along the dorsal and ventral roots
• The radicular arteries only feed locally into an area of the spinal cord. They don’t contribute massively to blood supply.

Question 18

Describe the great anterior segmental medullay artery

Answer 18

• AKA artery of Adamkiewicz
• Particularly large radicular artery
• Arises from an intercostal artery on the left between T9 and T11.
• Often supplies much of the blood to the lower spinal cord

Question 19

What does the great anterior segmental medullay artery (artery of Adamkiewucz) often supply?

Answer 19

Much of the blood for the lower spinal cord

Question 20

What does the anterior spinal artery supply?

Answer 20

~2/3 of the cross-sectional area of the spinal cord

Question 21

Where do the longitudinal veins of the spinal cord drain to?

Answer 21

Cerebellar veins and cranial sinuses

Question 22

Where do the segmental veins of the spinal cord drain to?

Answer 22

Local vertebral plexuses, and then into thoracic, abdominal or intercostal veins.

Question 23

Describe the space between the dura and the bone in the spinal canal

Answer 23

• Epidural space
• Contains:
  
  • adipose tissue
  • anterior and posterior epidural venous plexuses