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29 Cards in this Set
- Front
- Back
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Nerve
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Bundle of nerve fibers (myelinated or unmyelinated) surrounded by connective tissue sheath, the epineurium
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Ganglion (plural ganglia)
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Any thickening along a nerve due to the presence of large collective number of cell bodies
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Plexus
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A collection of nerves
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Synapse
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Electrochemical connection between nerve cells or nerve cells and their targets
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Composition of CNS vs. PNS
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CNS:
-brain + spinal cord PNS: -12 cranial nerves, (31 spinal nerves) 8 cervical, 12 thoracic, 5 lumbar, 5 sacral & 1 coccygeal |
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conus medullaris
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Where spinal cord ends at level of L2
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cauda equina
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nerve fibers from spinal cord continue down separately through the rest of the lumbar and sacral portion of the vertebral column known as the cauda equina
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meninges
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membranes that cover spinal cord
-dura mater -arachnoid mater -pia mater |
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Where do cell bodies for sensory (afferent) vs. motor (efferent) nerves lie?
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sensory:
-dorsal root ganglion, outside of CNS motor: -within CNS |
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dorsal (posterior) roots vs. ventral (anterior) roots of nerve travel
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dorsal root:
-taken by sensory impulses ventral root: -taken by motor impulses |
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spinal nerve
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composed of mixture of sensory and motor fibers that will travel dorsal and ventral roots, respectively, and join together to form a spinal nerve
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dorsal (posterior) vs. ventral (anterior) rami
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in order to reach the dorsal or ventral sides of the body, each spinal nerve splits into the correct rami
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somatic vs. autonomic
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somatic:
-control voluntary function autonomic: -control involuntary function |
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somatic motor nerve pathways vs. autonomic motor nerve pathways
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somatic motor nerve pathways:
-only require 1 neuron running from CNS to target autonomic motor nerve pathways: -require 2 neurons running from CNS to target -interrupted for synapse at ganglion (pre/post-ganglionic/synaptic fibers) |
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pre/post-ganglionic/synaptic fibers
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-autonomic motor nerve pathways
-portions of pathways before/after the ganglion where the synapses have occurred |
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autonomic & somatic sensory nerves
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-relay information back to CNS
-not interrupted for synapses b/c no peripheral ganglia at which synapses occur |
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thoracolumbar portion of autonomic system
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cell bodies of sympathetic nerves T1-L2 region of spinal cord
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paravertebral ganglia
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some sympathetic motor nerves synapse in the ganglia of the sympathetic trunk
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autonomic ganglia
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some sympathetic motor nerves synapse in the autonomic ganglia of the neck, thorax, abdomen, and pelvis
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prevertebral ganglia
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autonomic ganglia of the abdomen and pelvis
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places where sympathetic motor nerves can synapse
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-paravertebral ganglia
-autonomic ganglia (prevertebral ganglia = autonomic ganglia of abdomen & pelvis) |
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autonomic plexuses
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-where autonomic ganglia found
-celiac plexus -superior & inferior mesentrics (in the abdomen) -hypogastric plexuses (in the pelvis) |
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sympathetic splanchnic nerves
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most of preganglionic sympathetic motor fibers reaching these ganglia
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craniosacral portion of autonomic system
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cell bodies for parasympathetic nerves lie in brain stem (for cranial nerves III, VII, IX, X) & in sacral region of spinal cord
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places where parasympathetic motor nerves synapse
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-ganglia associated with some of cranial nerves
-wait & synapse in walls of target organs (examples: vagus nerve = cranial nerve X & sacral nerves = pelvic splanchnic nerves) |
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how do sympathetic get to target
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-travel up and down sympathetic trunk to reach other parts of body
-most hitch ride with somatic nerves from major somatic plexuses to reach their targets -some, in head and neck, hitch rides on major vessels (ex. internal carotid) for part of journey |
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how to parasympathetic get to target
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-in head and neck carried by four of the cranial nerves to, or near, targets
-cranial nerve 10 (vagus nerve)= longest autonomic nerve in body, innervation to thorax and much of abdomen -remainder of parasympathetic innervation for abdomen and pelvis covered by sacral portions of parasympathetic system -do not innervate any structures of limbs -pass through autonomic plexuses but do not synapse there |
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ventral rami
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-form large plexuses
-cervical plexus= innervate some muscles of the neck -brachial plexus= innervate upper limb -lumbar plexus= innervating part of lower limb, part of perineum & abdominal wall -sacral plexus= innervating part of lower limb & part of perineum |
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referred pain
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-pain sensation from viscera poorly localized
-inappropriately perceived as arising from site remote from actual location -autonomic sensory impulses enter spinal cord & painful visceral sensations can be "referred" to skin areas innervated by somatic nerves entering spinal cord at same spinal segments |
