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84 Cards in this Set

  • Front
  • Back
unit of structure of the nervous system
Neuron (nerve cell)
Name the 3 parts of the neuron
cell body, axon, and one or more dendrites
Cell body is the site of the
nucleus (location of metabolic machinery) Also refered to as a group of cell bodies in CNS
A group of neuron cell bodies outside the CNS is termed
Ganglion
One of two types of neuronal processes extending from the cell body
axon
The axon conducts impulses away from the cell body and toward the an
axon terminal (maybe assoc. w/ an effector organ (muscle) or another organ
Axon and assoc. coverings
nerve fiber
Cover all axons to some extent
Neurological cells
In the PNS neurological cells are called
Schwann cells
There are two types of nerve fibers
myelinated and unmyelinated
Myelinated axons are ensheathed by concentric wrappings of
Schwann cells plasma membranes.
Simple coverage by schwann cells without concentric plasma membrane wrapping is
unmyelinated
May be one in number but more frequently found as multiple short processes
Dendrites
Conduct impulses recvd from other neurons or sensory recpt. toward cell body
Electrical impluses travel through the cell body to the
axon
____________ of the cell body may also be receptive to impulses carried by axon of the axon of other neurons that synapse on the cell body
Plasma membrane
Neuronal Organization

Neurons are linked end to end even simple reactions may travel through ____ neurons
Several
Neuronal Organization

The functional contact at which an electrical impulse proceeds from axon terminal of one neuron to dendrite, cell body or axon of adj neuron is
Synapse
Neuronal Organization

Release of ______ from presynaptic terminals at synapses propagates the electrical conduction by postsynaptic neurons.
Neurotransmitters
Neuronal Organization

Two types of neurons most important in the course are the
Multipolar motor neurons and pseudounipolar sensory neurons
Neuronal Organization

Conduct impulses away from the CNS
Motor neurons (efferent)
Neuronal Organization

Conduct impulses toward the CNS
Sensory neurons (afferent)

Have single process bifurcates into peripheral process (conducts toward cell body) & central process (axon like) (conducts impulses away into CNS)
Neuronal Organization

All cell bodies of sensory neurons are located in ganglia outside the CNS but there are no ______ within sensory ganglia
synapses
Organization of Nervous Sys

NS is composed of the (anatomically)
PNS and CNS
Organization of Nervous Sys

The CNS is the
brain & Spinal Cord
Organization of Nervous Sys

PNS carries impulses to and from the
CNS
Organization of Nervous Sys
Perph nerves connected to the brain are
cranial nerves (12)
Organization of Nervous Sys

Perph nerves connected to the spinal cord are
spinal nerves (31)
Organization of Nervous Sys

Functionally the NS is divided into
Somatic (voluntary)
& autonomic (involutary)
Organization of Nervous Sys

Somatic is parts of both CNS & PNS provides ___&____ innervation to all parts of the body except viserca, smooth muscle, glands
sensory & motor
Organization of Nervous Sys

Somatic sensory fibers carry sensations of
touch, pain, temp, position to the CNS
Organization of Nervous Sys

Somatic motor fibers mediate contraction of skeletal muscle by ___ or ___ movement
voluntary or reflexive movement
Organization of Nervous Sys

The autonomic NS is concerned with the distribution of impulses to and from all
viscera, smooth muscles and glands (area of invol control) where ever located.
Organization of Nervous Sys

ANS is further divided into
SNS and PNS
Organization of Nervous Sys

All spinal nerves contain both
motor & sensory neurons

Some cranial contain both both other contain one or the other
Organization of Spinal Cord

spinal cord is a cylindrical structure located in the
vertebral canal
Organization of Spinal Cord

Spinal cords extends from
foramen magnum to the level of the second lumbar vert.
Organization of Spinal Cord

Spinal corld contains____ & ____ organized to transmit impulses in the required pattern
neuronal cell bodies and nerve fibers
Organization of Spinal Cord

Spinal nerves at each vertebral level exit the vertebral canal through the
intervertebral foramina
Organization of Spinal Cord

Spinal cord diameter is increased in cervical and lumbosacral seg. where nerves of the______ arise
limb plexuses
Organization of Spinal Cord

The spinal cord ends at the _______below the __ level of the vertebral canal
conus medullaris

L2
Organization of Spinal Cord

Nerves exiting the vertebral canal at lower levels continue inferior and this collection of elongated motor & sensory nerve rootlets is called
cauda equina
Organization of Spinal Cord

Cross section gray matter is the location of the _____ located centrally
nerve cell bodies

Arranged in an H shape directed anteroposterior
Organization of Spinal Cord

White matter contains nerve fibers is _____.
peripheral
Organization of Spinal Cord

Anterior (ventral) horns contain vertical columns of cell bodies of
somatic motor neurons
Organization of Spinal Cord

At the level of T1-L2 spinal levels a lateral horn is present forming an
intermediolateral cell column of sympathetic pregang neurons of the ANS
Meningeal Coverings

Name the 3 connective layers of the verterbral canal
dura mater, arachnoid, pia mater
Meningeal Coverings

tough outermost coverfing of the cord separated from the vertevral body and arch by a venous plexus and fat
dura mater
Meningeal Coverings

a delicate membrane deep to the dura
arachnoid
Meningeal Coverings

lies between the dura and arachnoid layers.
subdural space
Meningeal Coverings

Meningeal Coverings

delicate strands of connective tissue ext from arachniod to the innermost layer (pia)
arachnoid trabeculae
Meningeal Coverings

is filled with CSF is the space formed by the cobweb-like arachnoid trabeculae
Subarachnoid space
Meningeal Coverings

Widened region of arachnoid below the conus medullaris is called the (bet. vertebral levels L2-S2)
lumbar cistern
Meningeal Coverings

The dura and arachnoid form a sleeve or tube surrounding the spinal cord and or spinal nerves down to vertbral level ___.
S2
Meningeal Coverings

Below S2 vert level meninges extend out with each segmental nerve as it passes to its
intevertebral foramen
The innermost ___ is closely applied to the spinal cord
pia mater
a specialization of the pia mater is a vertically oriented mebranous sheet that has a continous origin from both lateral borders of the cord
Denticulate ligament,

(between foramen the membrane projects laterally to attach the dura mater, lateral border appears serrated.
An extension of the pia mater from the inferior tip of the conus medullaris is the
filum terminale
Filum terminale extends from the inferior end of the conus medullaris to insert on the
coccyx
are continous with connective tissue coverings of each spinal nerve at intervertebral foramina and continous with the coverings surrounding the brain
meninges
Vasculature

Anterior spinal artery from the vertebral arteries runs a longitudinal course on the anterior surface of the spinal cord, recv. collateral circulation from the spinal from the
radicular arteries (branches of vertebral, deep cerv, ascend cerivcal, post intercostal lumbar and lateral sacral arteries
Vasculature

irregular paired vessels taht are branches of the vertebral artery and are also reinforced by radicular arteries
posterior spinal arteries

(a large radicular art from lower thoracic or upper lumbar supplies 2/3 blood supply to spinal cord
Clinically important as occlusion or surgical ligation has disatrous consequences
Great anterior radicular artery
Spinal Nerve Orgainization

How are the 31 pairs of spinal nerves segmentally arranged
8 Cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
C1 exits above the vertebra C8 exits below the seventh vert. All others exit the
vertebral canal
Small bundles of nerve fibers that arise segmentally from ant & post of the spinal cord are called
rootlets (single seg converge into single ant & post roots, ant contains efferent (motor) post contain afferent (sensory)
Anterior and Posterior roots of a single spinal level converge to form the
Spinal nerve near the corresponding intervertebral foramen
The posterior roots are the central process of the neurons of the
dorsal root ganglion (located dorsalateral to the spinal cord within the intervertebral foramina
After exiting the intervertebral foramnen the spinal nerve divides into
ventral (ant) and dorsal (post) primary rami (contain both sens. & motor)
Dorsal primary rami send branches that distribute to the
deep muscles, vasculature and sensory innervation of the back
distribute to the remainder of the body
Ventral primary rami
The division of the primary rami the spinal nerve is connected to
sympathetic trunk by rami communications
___ & ____ primary ramiof spinal nerves undergo further branching to reach the area of distribution of the nerve
Anterior & Posterior
Anastomoses of the ventral primary rami of several spinal nerves froms a
plexus

(different spinal nerve fibers group and regroup to form terminal nerves supplying the exteremity)
Dermatomes
areas of skin supplied by the sensory root of a single spinal nerve
Dermatomes follow a ______path
circumferential path of each spinal nerve around thorax and abdomen, there is overlap.
Functional Components of Spinal Nerves

All branches of spinal nerves contain
somatic motor fibers, somatic sensory fibers, autonomic sensory fibers and autonomic motor fibers
carry motor impulses to skeletal muscles
Somatic motor fibers
carry sensory impulses from somatic recpt. inferior to the head plus those in the skin of the post surface of the head
somatic sensory fibers
carry sensory impulses from .
autonomic sensory fibers
carry impulses to these same areas; smooth muscle, glands and viscera
autonomic motor fibers
Connective Tissue

composed of bundles of nerve fibers held together by connective tissue
periphreal nerves
surrounds the entire nerve and contains fatty tissue, blood, lymph vessels and nerve bundles
epineurium
surrounds each nerve bundle
perineurium
surrounds each nerve fiber
endoneurium