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22 Cards in this Set

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What does the spinal cord extend from?
From the foramen magnum of the skull to the disc opposite L1 and L2
Where is the cervical enlargement?
From C4 to T1. Need additional neurons for innervation of upper limbs
Where is the lumbosacral enlargement?
From L2 to S3. Additional neurons needed for innervation of lower limbs
What is the conus medullaris?
Very end of spinal cord. The tapered end of the spinal cord which includes sacral spinal cord segments
How many spinal cord segments are there?
31. 8 cervical. 12 thoracic. 5 lumbar. 5 sacral. 1 coccygeal.

31 pairs of spinal nerves; each segment gives rise to a pair of spinal nerves
What kind of nerves are in the lateral horn? in the intermediate gray?
Lateral horn has autonomic motor while intermediate gray has interneurons
What are the three layers of the meninges?
Dura mater, Arachnoid, Pia mater
Describe the dura mater
The outermost later.
-composed of dense connective tissue
-2 layers: periosteal layer (attaches to vertebrae) and meningeal layer (envelopes spinal cord)
-Between the periosteal and meningeal layers in an epidural space (fat filled and has a venous plexus)
-Between the meningeal layer and Arachnoid is a subdural space which is just a potential space
Describe the Arachnoid
-Located deep to the dura
-Is avascular (no vessels)
-tissue is thin and transparent
-deep to arachnoid is the subarachnoid space (filled with CSF)
What is a lumbar cistern?
-inferior part of the subarachnoid space
-located in lumbar region
-region where samples of CSF can be taken from
-ends inferiorly to at S2 vertebral level
Describe Pia Mater
-Deepest meningeal layer
-Firmly attached to surface of spinal cord
-Cannot be dissected grossly
What is the filium Terminale?
-threadlike strand of the pia mater that leaves the conus medullaris and descends among the nerve roots of the cauda equina.
-Courses inferiorly through the middle of the lumbar cistern and is surrounded by the cauda equina (bundle of spinal roots)
-Becomes covered by the arachnoid and dura inferior to the S2 vertebral level to form the coccygeal ligament
What is the coccygeal ligament?
This ligament anchors the spinal cord and meninges inferiorly to the coccyx
What is the spinal nerve made of?
Union of dorsal and ventral roots.
-contains both sensory and motor axons.
-leaves vertebral column via intervertebral foramen
-distal to the intervertebral foramen, it divides into two braches (rami)
What is the dorsal primary ramus?
-different from dorsal root
-has both sensory and motor fibers
-innervates skin and deep muscles of the back
What is the ventral primary ramus?
-bigger than dorsal ramus
-innervates upper and lower limbs, and anterolateral trunk
-innervates superficial and intermediate muscles of the back
-contains both sensory and motor fibers
-contributes to major plexuses in the body (brachial plexus)
What are communicating rami?
White communicating rami contains myelinated axons of preganglionic symp. neurons and afferent axons from visceral organs

Gray communicating ramus contains postganglionic symp. axons
What is the cauda equina?
-bundle of spinal nerve roots in the subarachnoid space caudal of the termination of the spinal cord
-dorsal and ventral roots of lower lumbar and sacral spinal nerves
-sacral end of spinal cord (conus medullaris) is opposite the disc between L1 and L2
-lower spinal nerve roots must travel within the lumbar cistern to reach their respective intervertebral foramina
-within the lumbar cistern, they surround the filium terminale
What are dermatomes?
-specific skin segments innervated by a specific spinal nerve
-dermatome segments tend to overlap
What are myotomes?
-specific muscles that receive innervation by a particular spinal nerve
-muscles are usually innervated by two or more spinal nerves
What is a plexus?
The mixing and sorting of specific spinal nerves for distribution to muscles and skin in the periphery
What is the brachial plexus?
-formed by the ventral primary rami of spinal nerve segments C5 to T1
-nerves that innervate the upper limb