Lecture 2: Spinal Cord and Meninges Flashcards
Describe each meningeal layer.
The dura mater is the outermost meningeal layer. It is thick and tough, and provides mechanical protection. The dura mater is continuous with epineurium.
The arachnoid mater is next: it is cellophane/spiderweb-like.
The pia matter is the innermost meningeal layer. It is very thin and looks like a shiny coat of paint on the neural tissue. It cannot be separated from the neural tissue.
What is the clinical significance of the internal vertebral venous plexus?
This plexus provides a connection between the vessels that feed the pelvic organs – which are prone to cancer – and the nervous system. It is a common path of metastasis.
Describe the denticulate ligament.
This is a specialization of pia mater that helps stabilize the spinal cord. It has a free lateral edge, and every so often attaches (via denticles) to the dura mater.
Describe the spaces between the meningeal layers.
Outermost space: epidural space. Mostly fat as well as internal vertebral venous plexus.
The subdural space is below the dura mater. This is only a potential space in healthy people.
The subarachnoid space is under the arachnoid mater. It is filled with CSF, and the pressure from this layer is what keeps the arachnoid mater in contact with the dura mater. The CSF provides shock absorption.
A surgeon is trying to distinguish the T1 dorsal ramus from the ventral ramus. What should s/he look for?
The denticulate ligament. The dorsal and ventral rami are named in relation to the denticulate ligament.
As the result of a severe burn to the skin of his arm, patient has intractable pain in the skin of
several adjacent dermatomes. A surgeon can permanently relieve the pain, without paralyzing
any muscle, by severing what?
The dorsal root of the spinal nerves associated with those dermatomes.
Where does the neural tissue of the spinal cord end, and how does this affect spinal nerve development?
Spinal cord ends ~L1/L2. The cord itself does not grow much from infancy. However, the spinal column does lengthen. Nerves are constrained to exit at the level they exited at in development, so the nerve ROOTS must elongate as the spinal column elongates.
What is the cauda equina?
A collection of elongated nerve roots below the end of the spinal cord (~L1/L2). It is located in the subarachnoid cistern, and surrounded by CSF.
What is the conus medularis?
End of the spinal cord.
What extends off of the tip of the conus medularis?
The filum terminale internus. This is a specialization of pia mater, and helps stabilize the spinal cord. It extends and tethers to the coccyx.
Where do all three meningeal layers converge?
The filum terminal internus. This is attached to the coccyx, below the cauda equina and creates the end of the dural sac.
Describe the major arteries of the spinal cord.
There is one anterior spinal artery and two posterior spinal arteries.
Segmental arteries feed these arteries.
Describe the blood supply to the spinal arteries.
Anterior/Posterior medullary arteries: reach spinal cord and anastomose with spinal arteries.
Radicular arteries: reach spinal nerve roots.
Radiculospinal arteries: reach both spinal nerve roots and the spinal cord.
What is a particularly clinically significant radicular artery ?
Major radicular artery of Adamkiewicz is often clamped during abx surgery (especially for AAA). It is a major feeder of the spinal arteries. If it is clamped for too long there is a risk of ischemia of the neural tissue, which can result in neurological deficiencies.
Describe the tract of an upper motor neuron.
Corticospinal tract: brain to spinal cord. Originates in the motor cortex of the brain, and crosses the midline (so TBIs often result in contralateral deficits) before synapsing with LMNs in the ventral horn of the CNS.
