Ch. 13 - Spinal Cord Flashcards
What are some functions of the spinal cord?
- process reflexes
- integrate EPSPs and IPSPs
- conduct sensory impulses to brain and motor impulses to effectors
What are the meninges and spaces from superficial to deep?
epidural space dura mater subdural space arachnoid mater subarachnoid space pia mater
What is the removal of CSF called and why is this done?
spinal tap/lumbar puncture; used to diagnose pathologies, administer drugs
Why are spinal taps usually performed between L3-L4 or L4-L5 in adults?
to avoid damaging the spinal cord that ends at L1-L2
Where is the cervical enlargement in the spinal cord? Where is the lumbar enlargement?
C4-T1; T9-T12
Describe to ratio of white matter to grey matter along the spinal cord
going down the spinal cord, the ratio of white to grey DECREASES due to more sensory neurons (axon tracts) at higher levels
What are the functions of white matter?
nerve transmission to and from brain
What are the functions of grey matter?
integration of nerve impulses (EPSPs, IPSPs)
What are the posterior grey horns of the SC?
where sensory info enters
- axons of sensory neurons
- axons + cell bodies of interneurons
- somatic and autonomic
What are the anterior grey horns of the SC?
where output exits
- somatic motor nuclei to sk muscles
What are the lateral grey horns of the SC?
autonomic motor nuclei to autonomic effectors (cardiac/smooth muscle, glands)
How is white matter organized in the SC?
- divided into anterior, posterior, and lateral columns
- contain tracts (axon bundles in CNS)
What are 2 non-reflex functions of the SC?
grey - receives and integrates incoming/outgoing info
white - nerve impulse conduction to and from brain
How are the 31 pairs of spinal nerves named and numbered?
according to region and level of vertebral column from which they emerge (8C, 12T, 5L, 5S, 1C)
As spinal nerves are part of the PNS, how do they connect to the CNS?
via 2 bundles of axons (roots):
- posterior root (contains sensory axons; afferent)
- anterior root (contains motor axons; efferent)
Where are the cell bodies of sensory nerves?
posterior root ganglion
Why is there a posterior root ganglion but not an anterior root ganglion?
because motor cell bodies are within the spinal cord (in the anterior grey horns)
What is a possible of the formation of nerve plexuses instead of anterior rami directly going to part they supply?
safety feature; plexuses allow conduction of info even if one spinal nerve is cut; other nerves can carry info in/out
Why is there thoracic plexus?
anterior rami of spinal nerves T2-T12 directly innervate the intercostal spaces (intercostal nerves)
What are dermatomes?
specific segments of the skin that are innervated by all spinal nerves (except C1)
- spinal nerves carry sensory nerve impulses to spinal cord and brain
What is transection?
injury that severs spinal cord; loss of sensation and motor control below level of injury
- the higher the level of injury, the more severe the effect is
What is a reflex?
a fast, predictable, involuntary response to changes in the environment that helps maintain homeostasis
Where are spinal reflexes integrated?
grey matter of spinal cord
What are the 5 components of a reflex arc?
sensory receptor, sensory neuron, integrating center, motor neuron, effector
