Ch 13 Spinal Cord, Spinal Nerves & Spinal Reflexes
Dorsal root ganglia
- contain cell bodies of unipolar, sensory neurons - Lump on dorsal nerve root
Somatic motor nuclei
-(anterior) innervate skeletal muscle -the anterior horns of the spinal cord contain?
motor nuclei
-The cell bodies of neurons that issue commands to peripheral effectors are called - gray matter - anterior horns
sensory nuclei
-The cell bodies of neurons that receive and relay information from peripheral receptors are called - gray matter - posterior horn
Somatic and visceral sensory nuclei
-The posterior horns of the spinal cord contain
What is reciprocal inhibition?
-When antagonist relaxes due to contraction by agonist. - stimulate one set of muscles and inhibit the antagonist of another set of muscles
Mixed nerves
-contain both afferent (sensory) and efferent (motor) fibers -All spinal nerves are mixed nerves!
List the five steps involved in a neural reflex
1. Arrival of stimulus and activation of receptor 2. Activation of sensory neuron 3. Information processing in the CNS 4. Activation of motor neuron 5. Response of peripheral effector
Spinal nerve
A dorsal and ventral root of each spinal segment unite to form a
reflex
A predictable response to stimulus
Significance of a dermatome
A problem to a dermatome may indícate damage to an area of a specific nerve and can pinpoint injury to the area of the spinal cord
descending tracts
Axons convey motor commands down into the spinal cord by way of
ascending tracts
Axons that carry sensory information toward the brain
General Characteristics of Polysynaptic Reflexes
1. Involve pools of interneurons that inhibit and excite 2. Are intersegmental in distribution 3. Involve reciprocal inhibition 4. Have reverberating circuits Which prolong reflexive motor response 5. Several reflexes cooperate To produce coordinated, controlled response ———————- 1. Involve pools of interneurons that can inhibit and excite 2. Intersegmental 3. Reciprocal Inhibition 4. Reverberating Circuits 5. Reflexes may cooperate
What are the five parts of a neural reflex
1. Receptor 2. Sensory neuron 3. Integrating center 4. Motor neuron 5. Effector
What are the four pairs of plexuses?
Cervical plexus Brachial plexus Lumbar plexus Sacral plexus (includes coccygeal)
Myotome
Group of muscles innervated by a single spinal nerve Stroke evaluation
Visceral motor nuclei
Lateral horns located only in the thoracic and lumbar segments contains
subarachnoid space
Space between arachnoid & pia mater contains cerebrospinal fluid CSF
denticulate ligaments
Strands that help anchor the cord, coming out of the pia mater
pia mater
The blood vessels servicing the spinal cord run along the surface of the? -clear, innermost layer -attached to the spinal cord
Perineurium
The connective tissue partition that separates adjacent bundles of nerve fibers in a peripheral nerve is referred to as the
reflex arc
The crossed extensor reflex involves a contralateral reflex arc (contra, opposite), because the motor response occurs on the side opposite the stimulus.
cauda equina
The nerves that collectively radiate from the conus medullaris are known as the
spinal meninges
The specialized protective membrane that surrounds the spinal cord is the
dermatome
The specific bilateral region of the skin surfaced monitored by a single pair of spinal nerves is known as the a region of body surface innervated by a single spinal nerve
reflex arc
The stretch, tendon, and withdrawal reflexes involve ipsilateral (ipsi, same + lateral, side) reflex arcs: The sensory stimulus and the motor response occur on the same side of the body.
plexus
complex network formed by ventral rami of most spinal nerves - not T2-T12
Endoneurium
covers the individual axon
conus medullaris
end of spinal cord at L1/L2
subdural space
space between dura mater and arachnoid mater Contains serous fluid
epidural space
space between the dura mater and inside the bony covering of spinal cord
Perineurium
surrounds bundles of axons (fascicles)
Epineurium
surrounds entire nerve (bunch of fascicles)
dura mater
thick, white, strong, shiny, fibrous outermost layer of the meninges surrounding and protecting the brain and spinal cord -Does not stretch
filum terminale
thin thread of fibrous tissue at end of conus medullaris, attaches to coccygeal ligament
arachnoid mater
weblike, delicate, middle layer of the three meninges