PNS and Spinal Cord Flashcards
what is the difference b/w afferent and efferent nerve fibers
afferent carries info in to CNS
efferent carries info out (exit )
which horn of the spinal nerve is responsible for motor impulses
anterior/ventral horn (efferent fibers)
which horn of the spinal nerve is responsible for sensory information
posterior/dosral horn (afferent)
what are the 3 wrappings around peripheral nerves
epinuerium, perineurium, and endoneurium
which nerve wrapping would surround the entire nerve fascicle and is continuous with the dura mater
epineurium
which nerve wrapping is continuous with the arachnoid mater
perineurium
major blood vessels in the brain exist b/w what 2 nerve wrappings
epineurium and perineurium
this part of a myelinated axon contains many Na channels and is involved in signal propagation down an axon
Nodes of Ranvier
what is the function of myelin
surrounds axons and insulates them which increases conduction velocity
what is the difference b/w the 2 types of cells that produce myelin
Oligodendrocytes - only in CNS and 1 cell can myelinate many axons
Schwann cells - only in PNS and 1 cell only myelinate 1 axon
Saltatory conduction
depolarization jumps from node to node reknewing at each node
amplitude of signal conduction depends on ?
axon thickness
velocity of signal conduction depends on ?
myelination
what is a nociceptor
pain receptor
what is the general organization of a nerve receptor
specific receptive area, synaptic area (sends signal to CNS)
what is a receptive field
ability to convey information on the location of stimulus
T/F sensory receptors have the ability to adapt over time
T - adaptation occurs at receptor level but CNS can regulate receptor sensitivity
what are the 2 types of encapsulated receptors
muscle spindles, and golgi tendon organs
what do muscle spindles detect
detect muscle length
what do golgi tendon organs detect
detect muscle tension
what is the organization of the spinal cord segments
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccyx
all spinal nerves each innervate ____ dermatome except ?
1, C1
what is the conus medullaris
caudal end of the spinal cord
where are the 2 enlargements of the spinal cord ?
cervical (C5-T1) and lumbar (L2-S3)
what level cross section of the spinal cord would reveal an oval shape
cervical transverse section
a cross section at what level of the spinal cord would have the most gray matter
lumbosacral transverse section
what is the point of communication of the spinal cords at the midline called
anterior white commisure
gray matter at all transverse sections of the spinal cord is what shape
H-shaped
the substantia gelatinosa is found where on the spinal cord and is responsible for what ?
located in the posterior/dorsal horn
area that responds to pain and temperature sensory info.
alpha or lower motor neurons innervate muscles _____ whereas gamma motor nuerons innervate ____ ?
alpha = muscle fibers gamma = muscle spindles
what are the 2 specialized collumns that are found in the anterior horn at the cervical level
spinal accessory nucleus - forms accesory nerve
phrenic nucleus - forms phrenic nerve
preganglionic sympathetic neurons are located where
T1-L3 in intermediate horn
where is Clarke’s nucleus found and what is it responsible for ?
intermediate horn from T1-L2 and involved with proprioception of the leg
which cross section of the spinal cord would show the least white matter
sacral cross section
where would you perform a lumbar puncture and why ?
L4-L5 because the actual spinal cord stops at L1-L2
how is the spinal cord attacthed to the dura mater
filum terminale - anchors the conus medullaris to end of dural sheath
where are the cauda equina nerve fibers found
L1-S2 (from end of cord to end of dura)
what is the function of denticulate ligaments
lateral anchoring of the spinal cord
what type of reflex does not involve interneurons
stretch reflex
the stretch reflex is monosynaptic, what does that mean
1 synapse b/w 2 neurons
muscle tension can inhibit motor neurons, what encapsulated receptor sensed this
golgi tendon organ
what is another name for the great vertebral radicular artery
artery of Adamkiewicz
