The Spinal Cord

Question 1

describe the anatomical course of the spinal cord

Answer 1

• The spinal cord arises cranially as a continuation of the medulla oblongata.
• It then travels inferiorly within the vertebral canal, surrounded by the spinal meninges containing cerebrospinal fluid.
• At the L2 vertebral level the spinal cord tapers off, forming the conus medullaris.

Question 2

what happens to the spinal nerves at the end of the spinal cord?

Answer 2

The spinal nerves that arise from the end of the spinal cord are bundled together, forming a structure known as the cauda equina.

Question 3

where is the cervical enlargement of the spinal cord? and what does this represent?

Answer 3

The cervical enlargement is located proximally, at the C4-T1 level. It represents the origin of the brachial plexus.

Question 4

where is the lumbar enlargement of the spinal cord? what does this represent?

Answer 4

Between T11 and L1 is the lumbar enlargement, representing the origin of the lumbar and sacral plexi.

Question 5

what are the spinal meninges called and what is their function?

Answer 5

The spinal meninges are three membranes that surround the spinal cord – the dura mater, arachnoid mater, and pia mater. They contain cerebrospinal fluid, acting to support and protect the spinal cord.

Question 6

what do the meninges form distally?
what is its function?

Answer 6

Distally, the meninges form a strand of fibrous tissue, the filum terminale, which attaches to the vertebral bodies of the coccyx. It acts as an anchor for the spinal cord and meninges.

Question 7

describe the dura matter

Answer 7

The spinal dura mater is the most external of the meninges. It extends from the foramen magnum to the filum terminale, separated from the walls of the vertebral canal by the epidural space.

Question 8

describe the arachnoid matter

Answer 8

The spinal arachnoid mater is a delicate membrane, located between the dura mater and the pia mater. It is separated from the latter by the subarachnoid space, which contains cerebrospinal fluid.

Question 9

distal to the conus medullaris, the subarachnoid space….

Answer 9

expands forming the lumbar cistern which is accessed during lumbar puncture and spinal anasthesia

Question 10

describe the pia matter

Answer 10

The spinal pia mater is the innermost of the meninges. It is a thin membrane that covers the spinal cord, nerve roots and their blood vessels. Inferiorly, the spinal pia mater fuses with the filum terminale.

Between the nerve roots, the pia mater thickens to form the denticulate ligaments. These ligaments attach to the dura mater – suspending the spinal cord in the vertebral canal.

Question 11

describe the formation of spinal nerves

Answer 11

Each spinal nerve begins as an anterior (motor) and a posterior (sensory) nerve root. These roots arise from the spinal cord, and unite at the intervertebral foramina, forming a single spinal nerve (mixed).

Question 12

what happens after the spinal nerve leaves the vertebral canal via the vertebral foramina?

Answer 12

it divides into two:
- posterior rami
- anterior rami

Question 13

what is the function of the posterior rami?

Answer 13

supplies nerve fibres to the synovial joints of the vertebral column, deep muscles of the back, and the overlying skin.

Question 14

what is the function of the anterior rami?

Answer 14

supplies nerve fibres to much of the remaining area of the body, both motor and sensory.

Question 15

describe the arterial supply of the spinal cord

Answer 15

The arterial supply to the spinal cord is via three longitudinal arteries – the anterior spinal artery and the paired posterior spinal arteries.