NAS - Basic Topography of the Spinal Cord and Nerves (AP05)

spinal cord innit

How many pairs of spinal nerves are present in the human body?

31 pairs:

• 8 pairs of cervical nerves

• 12 pairs of thoracic nerves

• 5 pairs of lumbar nerves

• 5 pairs of sacral nerves

• 1 pair of coccygeal nerves

Where does the spinal cord end?

at the L1/L2 vertebral level, where it forms the conus medullaris

Where does the dura mater in the spinal cord end?

Extends all the way to coccyx region

Where does the arachnoid mater of the spinal cord and subarachnoid space end?

At the sacral region

Where does the pia mater of the spinal cord end?

Ends at the conus medullaris at the L1-L2 level

What do the lumbar and sacral nerve roots form?

Cauda equina

What are the differences between the ventral and dorsal horn?

Dorsal horn: contains the cell bodies of sensory neurones, responsible for sensory processing

Ventral horn: contains the cell bodies of somatic motor neurones that control skeletal muscles

What is the lateral horn?

• Contains cell bodies of autonomic motor neurones which innervate cardiac muscle, smooth muscle and glands.

• Origin of the autonomic nervous system

Which regions are the lateral horn found in?

Thoracic, upper lumbar and sacral regions

What is the organisation of the grey and white matter in the spinal cord?

• Grey matter of the spinal cord has a symmetrical butterfly appearance

• White matter surrounds this structure

Where are lumbar punctures performed?

Done specifically at L3-L4 or L4-L5 interspace to avoid damage to the conus medullaris

Why are lumbar punctures performed?

To either extract CSF from the subarachnoid space or to inject medication

What is A, B and C?

A - Dorsal root

B - Ventral root

C - Dorsal root ganglion

Identify the following features of the vertebral column.