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67 Cards in this Set
- Front
- Back
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what is the nervous system divided into?
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CNS
PNS |
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what is the function of the nervous system?
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conscious perception, voluntary movement, autonomic integrative functions
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what are the nerves associated with the brainstem called?
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cranial nerves
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what are the nerves associated with the spinal cord called?
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spinal nerves
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how many pairs of cranial nerves are there?
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12
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how many pairs of spinal nerves are there?
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31 pairs
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how are the spinal nerves numbered?
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they are numbered according to the level of the vertebral column with which they are associated
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what is the structural and functional unit of the nervous system ?
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Neuron
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what does the neuron include?
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Nerve cell body
Dendrites Axons |
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describe what the dendrite does?
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dendrites are usually short and receive impulses and direct them toward the nerve cell body
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describe the function of the axon of a nerve?
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the axon is usually single and carries impulses away from the cell body to the dendrites of other neurons or to an effector organ
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what are the classifications of neurons?
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Unipolar
bipolar Multipolar |
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Unipolar neuron
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are sensory neurons and have a single process that divides into two axons
these are located in spinal ganglia (DRG) and the mesencephalic nucleus of CN V |
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Bipolar neuron
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are sensory and usually associated with special senses
-Retina of the eye and olfactory epithelium |
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Multipolar neuron
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have many dendrites and a single axon
These are motor in function and located in the ventral horn gray matter and intermediolateral cell column of the spinal cord and autonomic ganglia |
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what are groups of neurons associated with the PNS called?
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ganglia
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what are groups of neurons within the CNS called?
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Nucleus
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what are the connective tissue elements that bundle nerve fibers forming spinal nerves?
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Epinerium, Perineurium, and Endoneurium
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what forms a spinal nerve
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dorsal and ventral roots
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what is the breakdown of spinal nerves?
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8 cervical
12 thoracic 5 lumbar 5 sacral 1 coccygeal |
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what does the ventral root of a spinal nerve contain?
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motor or efferent fibers from motor neurons located in the ventral horn gray matter of the spinal cord
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What does the dorsal root of a spinal nerve contain?
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sensory/afferent and is formed from axons of unipolar neurons located in the spinal or dorsal root ganglia
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Describe the divisions of the spinal nerve as it leaves the intervertebral foramen.
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The dorsal & ventral roots merge distal to the spinal ganglia forming the spinal nerve.
The spinal nerve leaves the vertebral canal through the intervertebral foramen and at the forman divides into a dorsal primary ramus and a ventral primary ramus. Each containing motor and sensory fibers |
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how are the dorsal primary rami distributed throughout the body?
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the dorsal primary rami for the most part remain separate and are distributed segmental fashion to the musculature (motor) and skin (sensory) of the back.
The ramus eventually divides into medial and lateral branches Each branch will supply musculature while only one will supply the skin |
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Is the dorsal primary ramus involved in plexus formation?
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NO
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where does the ventral primary ramus provide innervation to?
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ventral primary rami supplies sensory and motor innervation to the lateral and anterior regions of the trunk and to the limbs
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what is one example of a ventral primary ramus?
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intercostal nerves
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Do ventral primary rami form plexi?
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YES
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what are the major nerve plexuses found in the body?
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1. cervical
2. brachial 3. lumbar 4. sacral |
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what is the function of a plexus formation ?
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Plexus formation allows a spinal nerve to have a much wider distribution over a given area
Spinal cord segment can contribute to more than one nerve or several spinal cord segments to one nerve |
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how are nerves that arise from plexuses named?
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1. Position (ulnar)
2. Distribution (lateral femoral cutaneous n.) |
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what does each named nerve from a plexus contain?
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Each named nerve derived from a plexus will usually contain elements (fibers) from tow or more spinal nerves
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GSA
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General Somatic Afferent
Sensory information from the dermatomes of the body |
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GVA
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General Visceral Afferent
sensory information from the viscera |
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what type of neuron carries GSA and GVA type modalities?
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These modalities are carried by the UNIPOLAR neurons of the DRG and this information is carried to the dorsal horn gray matter of the spinal cord through the dorsal root
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where do GSA fibers synapse?
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some of the GSA fibers will synapse on interneurons that in turn synapse on large motor neurons in the ventral horn gray matter of the spinal cord (reflex activity) and others will go to higher centers for conscious perception
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Where do GVA neurons send their processes?
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GVA neurons send their processes to synapse on smaller multipolar neurons in the lateral horn gray matter
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GSE
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General Somatic Efferent
the motor neurons in the ventral horn gray matter send their axons to skeletal muscle underlying the skin in a particular dermatome region |
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What is the sympathetic motor modality classified as?
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GVE
general visceral efferent |
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How do GVE and GSE motor modalities leave the spinal cord?
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both of these motor modalities leave the spinal cord via the ventral root
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what is a superficial reflex
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depend on the integrity of the appropriate sensory and motor peripheral nerves and cord segments
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Abdominal reflex
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Upper quadrant test segments T7-T9
Lower quadrant test segments T10-T12 scratch the skin of any quadrant some distance from umbilicus this causes the underlying muscle to contract |
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Cremasteric reflex
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Tests segments L1-L2
stroke the skin on medial side of thigh which causes cremaster muscle to contract which elevates testis on that side |
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Plantar reflex
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Test segments L5-S1
scratch sole of foot on lateral aspect from heel to toe This results in plantar flexion of toes |
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Anal reflex
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TEst segments S2-S4
scratch perianal skin results in contraction of external sphincter ani muscles which pucker the anus |
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what is a deep tendon reflex
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muscle spindle and tendon organs are sensory (afferent) endings that sense the degree of tension in a muscle and tendon. These reflexes are commonly tested to determine the integrity of segmental innervation of certain muscles
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Biceps brachii deep tendon reflex
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C5 & C6
tapping biceps tendon causes flexion of the elbow joint |
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Brachioradialis deep tendon reflex
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C5, 6 & 7
tapping insertion of tendon causes supination of radioulnar joint |
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Triceps deep tendon reflex
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C6, 7, and 8
tapping triceps tendon causes extension of the elbow joint |
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Quadriceps femoris deep tendon reflex
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test L2,3, and 4
tapping patellar tendon causes extension of the knee joint |
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Achilles tendon reflex
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S1 & S2
tapping tendon results in plantar flexion of ankle joint |
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what is the autonomic nervous system defined as?
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primarily a motor system composed of tow neurons
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describe the two types of neurons found in the autonomic nervous system
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first neuron: located within the CNS
2nd neuron: within a ganglion in the PNS |
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what is the term for the autonomic nervous system neuron within the CNS
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presynaptic
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what is the term for the autonomic nervous system neuron found within the PNS?
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Postsynaptic
the axon of the presynaptic neuron will synapse on the 2nd order neuron in the PNS ganglion. |
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Where do the postsynaptic neurons synapse?
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The axons from the nurons of the ganglion are postsynaptic and reach end organs within major organs and blood vessels of the body
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True or False
Some sensory fibers are carried in autonomic nerves |
TRUE
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what are the two major divisions of the ANS?
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sympathetic and parasympathetic systems
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where does the sympathetic nervous system arise from ?
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spinal levels T1-L3
termed thoracolumbar outflow |
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Where does the parasympathetic nervous system arise from?
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PS Nervous system arises in motor divisions of cranial nerves 3,7,9, and 10 and sacral spinal levels S2, S3, S4.
termed craniosacral outflow |
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what is the sympathetic nervous system closely associated with?
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The sympathetic nervous system is closely associated with and is a component of the spinal nerves
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describe the origin of the sympathetic nervous system
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the sympathetic nervous system originates from the presynaptic cell bodies located in the intermediolateral cell column (T1-L3)
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How do axons of the preganglionic sympathetic fibers exit the spinal cord?
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Preganglionic fibers leave the spinal cord through the ventral root and become components of the spinal nerves
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What is a white rami communican?
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The presynaptic fibers leave the ventral primary rami of spinal nerves and enter the sympathetic chain at that level. The presynaptic fiers are myelinated as the other fibers of the ventral root and form the WHITE RAMI COMMUNICANS that extend from the spinal nerves to the sympathetic chain
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where do white rami communicans synapse?
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some fibers will synpase on the postsynaptic neurons (2nd order) in the sympathetic chain (paravertebral) ganglion of that level
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what are gray ramus communicans?
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The postsynaptic fivers (axons which are unmyelinated) will leave the ganglion through the gray ramus communicans and distribute back into the spinal nerve of the same level. They then become part of the dorsal and ventral primary rami of the spinal nerve and innervate blood vessels, sweat glands, and smooth muscle
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How is the abdominopelvic splanchnic nerves formed?
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some of the presynaptic fibers pass through the sympathetic chain without synapsing and form the abdominopelvic splanchnic nerves
These fibers synapse on postsynaptic neurons in prevertebral ganglia. |
