Spinal meninges and nerve roots
On completion of this study unit you will be able to:
- Name and describe the three meningeal layers which surround the spinal cord.
- Identify the spaces between each meningeal layer.
- Describe the nerve rootlets and roots of the spinal nerves.
The spinal cord is enveloped by the three meningeal coverings which, from superficial to deep, are known as the dura mater, arachnoid mater and pia mater. They are continuous with their counterparts surrounding the brain at the foramen magnum and function to suspend and protect the spinal cord within the vertebral canal. They also house blood vessels that supply the spinal cord and form a continuous cerebrospinal fluid (CSF) filled cavity which surrounds the spinal cord.
Also enveloped (partially or fully) by the outer two meningeal layers are numerous motor and sensory rootlets which contribute to the eventual formation of spinal nerves. These rootlets arise from the anterolateral and posterolateral sulci of the spinal cord and are therefore known as the anterior and posterior rootlets. They contain the axons of sensory and motor neurons that function to transmit information to and from the spinal cord. Within the vertebral canal, these rootlets extend and coalesce to form the anterior and posterior roots of the spinal nerves which then combine and exit the vertebral canal via the intervertebral foramina as spinal nerves.
Find out more about the meninges and nerve roots of the spinal cord by watching the video below.
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Take a closer look at the spinal meninges and nerve roots of the spinal cord in the galleries below.
Dura mater: Surrounds filum terminale and terminates at S2 vertebral level
Arachnoid mater: Fuses with dura mater and terminates at S2 vertebral level
Pia mater: Extends as a coating of the filum terminale which reaches S2 vertebra
|Spaces||Epidural space, subdural space, subarachnoid space|
Origin: Posterolateral sulcus of spinal cord
Posterior rootlets → posterior roots (spinal ganglion): sensory fibers
Origin: Anterolateral sulcus of spinal cord
Anterior rootlets → anterior roots: motor/autonomic fibers
Anterior roots + posterior roots → mixed spinal nerve
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