Overview of Nervous System Flashcards
neuron structure
cell body (soma) + dendrites + axon
dendrites
neurons can have one, none, or many; brings information to the cell body
axon
neuron can have only one; transmits information to other neurons and muscles
multipolar neuron
multiple dendrites extending from the cell body
unipolar neurons
no dendrites, just a single axon; have sensory receptors for receiving information from CNS
bipolar neurons
have one dendrite and one axon
CNS is composed of _
brain and spinal cord
PNS is composed of _
peripheral nerves and ganglia
meninges
3 layers of CT that protect brain and spinal cord
3 layers of meninges
dura mater, arachnoid mater, and pia mater
subarachnoid space
between the arachnoid and pia mater; filled with CSF
spinal cord ends at _
L1/L2
dura sheath extends to _
S2
_ cervical segments
8
_ thoracic segments
12
_ lumbar segments
5
_ sacral segments
5
_ coccygeal segments
1
conus medullaris
end of spinal cord
cauda equina
collection of nerve roots (L2 and below)
filum terminale
strand of fibrous tissue that extends from the end of conus medullaris to attach to the coccyx; contains pia mater
Where is CSF withdrawn in adults?
between L3 and L4
Where is CSF withdrawn in children?
between L4 and L5
endoneurium
surrounds individual axons
perineurium
surrounds bundle of axons (nerve fibers)
myelin surrounds each _
axon
afferent pathway
PNS to CNS (sensory)
efferent pathway
CNS to PNS (motor)
peripheral nervous system is made up of the _
somatic and autonomic nervous systems
autonomic nervous system is made up of the _
parasympathetic and sympathetic systems; general visceral efferent
somatic nervous system innervates _
body wall and limbs, skin, skeletal muscle, joints
visceral system innervates _
smooth muscle, cardiac muscle, and glands
dorsal ramus
brings sensory info from posterior
ventral ramus
brings sensory info from lateral and anterior
general somatic afferent route (from posterior stimulation)
sensory receptors –> dorsal primary ramus –> spinal nerve –> dorsal root –> spinal cord
somatic afferent fibers are _
unipolar
cell bodies for somatic afferent fibers reside in the _
dorsal root ganglion
somatic afferent route (from anterior stimulation)
sensory receptors –> ventral primary ramus –> spinal nerve –> dorsal root –> spinal cord
dermatome
cutaneous area supplied mainly by a single spinal nerve or segment (no C1 dermatome)
general somatic efferent fibers are _
multipolar neurons
cell bodies of somatic efferent fibers reside in _
ventral horn (where motor fibers reside)
somatic efferent route (posterior stimulation)
ventral root –> spinal nerve –> dorsal primary ramus
somatic efferent route (anterior stimulation)
ventral horn –> spinal nerve –> ventral primary ramus
visceral efferent fibers contain _
a two neuron connection (synapse)
parasympathetic nerves
cranial III, VII, IX, X; S2-S4
sympathetic nerves
T1-L2
both sympathetic and parasympathetic stimulate _
internal visceral organs
only sympathetic innervates _
peripheral viscera (blood flow & temp)
visceral efferent fibers are _
multipolar
cell bodies of the visceral efferent fibers (preganglionic neurons) reside in _
lateral horn
cell bodies of visceral efferent fibers (postganglionic neurons) reside in _
paravertebral ganglia
visceral efferent pathway (to peripheral viscera)
ventral root (T1-L2) –> spinal nerve –> white ramus –> paravertebral ganglion –> gray ramus –> spinal nerve –> dorsal/ventral primary ramus
How can the sympathetic nervous system innervate the entire body if they only have preganglionic neurons in T1-L2?
paravertebral ganglia
white rami are present in _
T1-L2; preganglionic
gray rami are located _
at all levels; post-ganglionic
visceral efferent route to internal visceral organs
does not use the gray ramus
visceral afferent route (from pain)
sensory receptors –> white ramus –> spinal nerve –> dorsal root –> spinal cord (no synapse)
