Chapter 13 [ EXAM #1 ] Flashcards
function of spinal cord
conduction path to and from brain
what are spinal reflexes
rapid, automatic response triggered by different stimuli
one or more spinal segments
can occur without brain input
how long and wide is spinal cord
~18 inches long and 0.5 wide
what is conus medullaris
condensed cord ends L1 -> L2
what are spinal enlargements
what are the two types
more gray matter in segments of spinal cord dedicated to limbs
cervical enlargement: nerves to and from upper limbs
lumbar enlargement: nerves to and from lower limbs
where is filum terminale
anchored to coccyx
what are three spinal meninges
dura mater: outer-most
arachnoid mater
pia mater: inner-most
what is meningitis
inflammation of meninges (dura, arachnoid, pia)
functions of meninges
protect spinal cord from:
- shocks, bumps, blows
- bone contact
- anchors spinal cord
carries blood supply, nutrients, and O2
space in dura mater and function
epidural space
filled with adipose, blood vessels
between dura mater and vertebral canal
what is in cranial end of dura mater
occipital bone periosteum
what occurs in lateral end of dura mater
fuses with spinal nerve connective tissue
what is arachnoid mater
middle layer of meninges
what is in arachnoid mater
loose collagen and elastic fibers
function of subarachnoid space
circulates CSF
contains motor and sensory components
spinal anesthesia
CSF withdrawal
where is dura mater
outermost layer
what forms dura mater
dense collagen
where is pia mater
inner most
is pia mater durable or delicate
delicate
what runs onto of pia mater and where
blood vessels in subarachnoid space
function and location of denticulate ligaments
prevent lateral movement
from pia to dura mater
function of pia mater
anchors spinal cord
marks left and right sides of spinal cord
anterior median fissure
posterior median sulcus
what composes white matter
myelinated and unmyelinated axons
what composes gray matter
neuron cell bodies and unmyelinated axons
what are nuclei
functional group of neuron cell bodies in spinal cord
describe the four nuclei in the spinal cord in order from posterior to anterior
somatic sensory
visceral sensory
visceral motor
somatic motor
is sensory information processed through the ventral or dorsal gray horns?
dorsal
is motor information processed through the ventral or dorsal gray horns?
ventral
what describes axons crossing from side to side in the gray matter of the spinal cord
gray commissure
what are three funiculi / white columns
posterior funiculi
anterior funiculi
lateral funiculi
what describes axons crossing from side to side in the spinal cord in the white matter of the spinal cord
anterior white commissure
what are tracts
bundles of axons
run up and down columns for communication
what carries sensory info up spinal cord to brain
ascending sensory tracts
what carries motor info down spinal cord from brain
descending motor tracts
what type of nerves are spinal nerves
mixed nerves
afferent sensory and efferent motor
how are endoneurium, perineurium, and epineurium organized?
endoneurium surrounds axons
perineurium surrounds fascicles
epineurium surrounds nerve
what are dermatomes
area of skin innervated by single spinal nerve
significance of dermatomes
spinal cord injury: determine loss of skin sensation helps identify damaged nerves
shingles rash: follows dermatome of affected spinal nerve
name two proximal branches of spinal nerves
dorsal / posterior root
ventral / anterior root
name two distal branches of spinal nerves
dorsal / posterior ramus
ventral / anterior ramus
rami communicantes = communicating rami
what are roots
two bundles of axons into and out of spinal cord segment
function of dorsal / posterior root
sensory info into spinal cord nerves
what composes the dorsal / posterior root
dorsal root ganglion: sensory neuron cell bodies
dorsal horns: sensory nuclei of interneurons
function of ventral / anterior root
motor info leaving spinal cord horns
function of ventral ramus
sensory and motor from/to arms, legs
what forms intercostal nerves
thoracic branches
what forms ventral rami
nerve plexuses
what sends and receives info from and to the guts and glands
rami communicantes
what are nerve plexuses
networks of nerve fibers
what region are motor fibers found
T1 -> L2
what are reflexes
automatic response to specific stimuli with little synaptic delay
what is reflex arc
pathway followed by nerve impulse that generates reflex
opposes original stimulus
five steps of reflex arc
sensory receptor
sensory neuron
integrating center
motor neuron
effector
first step of reflex arc
sensory receptor
responds to stimulus
produces generator/receptor potential
second step of reflex arc
sensory neuron
axon conducts impulses from receptor to integrating center
third step of reflex arc
integrating receptor
region(s) within CNS that relay impulses from sensory to motor neurons
fourth step of reflex arc
motor neuron
axon conducts impulses from integrating center to effector
fifth step of reflex arc
effector
muscle/gland responds to motor nerve impulses
all five steps of reflex arc and their descriptions
1.) sensory receptor
responds to stimulus
produces generator/receptor potential
2.) sensory neuron
axon conducts impulses from receptor to integrating center
3.) integrating receptor
region(s) within CNS that relay impulses from sensory to motor neurons
4.) motor neuron
axon conducts impulses from integrating center to effector
5.) effector
muscle/gland responds to motor nerve impulses
how are reflexes classified
development
motor response
processing site
neural circuit complexity
what are two developmental reflexes
innate and acquired
what are two motor reflexes
somatic and visceral
what are two site-of-info-processing reflexes
spinal and cranial
what are two complexity-of-neural-circuit reflexes
monosynaptic and polysynaptic
what is monosynaptic reflex
direct sensory to motor neuron communication
minimal delay
brief
what is polysynaptic reflex
interneurons facilitate sensory-motor communication
long delay
a reflex that conducts on one side of the spinal cord is called…
ipsilateral
a reflex that conducts on both sides of the spinal cord is called…
contralateral
what is stretch reflex
monitors and regulates skeletal muscle length
stretch reflex operation
tendon is stretched
stimulates muscle spindles
a flexor reflex is also known as a…
withdrawal reflex
what is reciprocal inhibition
motor neurons controlling extensors inhibited white motor neurons controlling flexors stimulated
give an example of crossed extensor reflex
straightens opposite legs to support body weight when stepping on a tack
what Babinsky sign does an infant have and what does it do
positive Babinsky reflex
toes spread
what Babinsky sign does an adult have and what does it do
negative Babinsky reflex
toes curl
reason for positive Babinsky reflex in adult
damage to brain or to descending tracts
