Spinal Cord and Meninges

Question 1

What ligaments create the boundaries for the vertebral canal?

Answer 1

Ligamentum flavum, posterior longitudinal ligament, the supraspinous ligaments, and the intraspinous ligaments.

Question 2

What are the contents of the vertebral canal

Answer 2

Spinal cord.
Meninges (pia, arachnoid and dura mater).
Suparachnoid space containing CFS.
Spinal roots that from spinal nerves.
Extradural/epidural space
Blood vessels.

Question 3

Describe where the spinal cord begins and ends

Answer 3

Begins - foramen magnum, begins as a continuation of the mudulla oblongata.
Ends - L1/2 in adults. The inferior end of the cord is know as the conus medullaris that narrows to the filum terminale.

Question 4

Name the spinal enlargements, their plexuses and reason for existing.

Answer 4

• Cervical enlargement; Found between C4 and T1, contributes to the brachial plexus and supplies the nerves for upper limbs.

Lumbosacral enlargement; Found between T11-S1, contributes to the lumbosacral plexus and supplies the nerves for the lower limbs.

Question 5

Describe the spinal cord development

Answer 5

In embryo the spinal cord and vertebral column are the same length but as the vertebral column grows faster than the spinal cord, in neonates the spinal cord ends at L3.

Question 6

Describe the positioning of spinal nerves and their number.

Answer 6

There are 31 spinal nerves that each emerge from a specific invertebral foramen.

Question 7

What does dorsal and ventral mean?

Answer 7

Dorsal = posterior
Ventral = anterior

Question 8

Describe the changes that occurs to emerging nerves out of the spinal cord.

Answer 8

Emerge as dorsal and ventral rootles. Then form dorsal (separate sensory and motor) roots and ventral (separate sensory and motor) roots. Roots then become a spinal nerve (mixed sensory and motor) which become posterior and anterior rami which are also mixed sensory and motor.

Question 9

Describe the emerging nerves in relation to the vertebrate

Answer 9

Between C1-C7, nerves are named according to the vertebrate below. Except for the nerve C8. From T1-S5, the nerves are names after vertebrate above

Question 10

What is the cauda equina?

Answer 10

It is a bundle of spinal nerves and spinal nerve rootlets.

Question 11

Describe some of the features of the dura mater

Answer 11

• Outermost fibrous, protective layer.
• One layer in spine. Two layers in cranium (inner meningeal and periosteal)
• As it decends through the vertebral canal it is called the dural sac and does not attach to bone.
• Dural sac narrows and fuses with the filum terminal and eventually the coccyx
• Dura mater covers the roots of spinal nerves as they pass through the invertebral foamen

Question 12

Describe some of the features of the arachnoid mater

Answer 12

• Avascular layer that ends at S2
• Connects to pia mater via arachnoid trabeculae
• The subarachnoid space ends at S2, contains CSF and blood vessels. Encloses the caudal equina in the lumbar cistern

Question 13

Describe some of the features of the pia mater

Answer 13

• Inner most, vascular layer that covers the brain and spinal cord and surface of spinal rootlets.
• Becomes the filum terminal which attaches to the coccyx
• Has triangular extensions called denticulate ligaments that attach to the arachnoid mater and suspend the spinal chord.

Question 14

What suspends the spinal cord in the dural cord

Answer 14

Denticulate ligaments (extensions of the pia mater)

Question 15

Describe some of the features of the extradural space

Answer 15

• It has a fatty matrix
• Runs from the foramen magnum to the sacral hiatus
• Contains the internal vertebral plexus.

Question 16

What are the two sets of arteries that supply the spinal cord

Answer 16

• 3 Longitudinal arteries (typically branches of the subclavian artery, which lie on the surface of the spinal cord).
• Several segmental spinal arteries (Typically branches of the aorta, enter the vertebral canal vie intervertebral foramen at every level.

Question 17

What are the 3 longitudinal arteries that supply the spinal cord

Answer 17

• 2 paired posterior spinal arteries (arise from vertebral arteries and posterior inferior cerebellar arteries)
• 1 anterior spinal artery (arises from vertebral artery. Lies in the median fissure and gives off sulcal arteries).

Question 18

Describe some of the segmental arteries

Answer 18

• Segmental spinal arteries give off segmental medullary arteries (e.g. the great anterior segmental medullary artery).
• Cervical segmental arteries arise from vertebral arteries
• Thoracic segmental arteries arise from intercostal arteries
• Lumbar segmental arteries arise from lumbar arteries.

Question 19

Describe the venous drainage of the spinal cord

Answer 19

There are longitudinal channels of the surface of the cord that don’t have valves so blood can flow in any direction.

• Internal vertebral venous plexus (lies in the extradural fat in the epidural space)
• External vertebral venous plexus (Drains medullary cavity of the vertebral bodies and connects to segmental veins.

Question 20

Describe the layers which the needle must pass through when preforming a lumbar puncture

Answer 20

Skin
Superficial Fascia
Supraspinous ligaments
Interspinous ligaments
Ligamentum flavum
Epidural space
Dura mater
Arachnoid mater
Subarachnoid space

Question 21

Describe features of the grey matter in the spinal cord

Answer 21

Contains neuronal cell bodies within horns;
Lateral Horns - Visceral motor neurons
Dorsal horns - Interneurons
Ventral horns - Somatic motor neurons
and a central canal

Question 22

Describe the features of white matter in the spinal cord

Answer 22

Columns containing ascending and descending tracts. Columns are separated into;
Ventral columns
Lateral columns
Dorsal columns