The Spinal Cord, Spinal Nerves, & Injuries Flashcards
list the 3 structures that protect the spinal cord
- bone
- meninges
- CSF
where does the spinal cord end
at the conus medullaris (L1 or L2 in adults)
describe the caudal equina
collection of nerve roots
describe the function of the filum terminale
anchors the cord to the coccyx
describe the function of the meninges and the 3 layers from out to inner
Layers of connective tissue covering the spinal cord Layers: 1. Dura Mater 2. Arachnoid mater 3. Pia Mater
describe the characteristics of the dura mater
- tough outer covering
- not attached to the vertebral column
- ends at S2
describe the characteristics of the arachnoid mater
- loose middle covering layer
- separated from dura mater by subdural space (which contains blood vessels & CSF)
- ends at S2
describe the characteristics of the Pia mater
- connective tissue which clings to brain & spinal cord
- rich with tiny blood vessels
- projections that attach cord to the dura mater
how many pairs of spinal nerves
31
what axons do the dorsal roots contain
contains the axons of the sensory neutrons
where are the cell bodies of sensory neutrons found within
dorsal root ganglion
what is the function of the dorsal root
relays sensory input from receptors of the posterior body trunk to the spinal cord
what axons do the ventral roots contain
the ventral roots contain the axons of motor neurons
what is the function of the ventral roots
relay motor commands to effector glands & muscles of the rest of the trunk & limbs
list the 2 grooves of the spinal cord cross section
- ventral median fissure
2. dorsal median fissure
is the grey matter of the spinal cord on the inside or outside
on the inside which is connected by the grey commissure
what does the dorsal side of the spinal cord convey
incoming info = afferent = sensory
what does the ventral side of the spinal cord convey
outgoing info = efferent = motor
what forms the dorsal root
afferent (incoming) fibres carry impulses from peripheral sensory receptors forms the dorsal root
what forms the ventral horns
cell bodies of somatic motor neurones
what forms the lateral horns
cell bodies of automatic motor neurones that innervates internal organs
list how the spinal grey matter is organised into 4 different nucleis
- interneurons receiving somatic sensory neurones
- interneurons receiving visceral sensory neurones
- visceral motor (autonomic) neurones
- somatic motor neurones
list the 3 columns of the spinal cord white matter
- dorsal
- lateral
- ventral
describe the role of 2nd order neurones
transmit impulses to the thalamus or cerebellum where they synapse
describe the role of 3rd order neurones
relay impulses to somatosensory cortex of the cerebrum
list the ascending pathways
- dorsal column medial lemniscal pathway
- spinothalamic pathway
- spinocerebellar pathway
what impulses does the dorsal -medial lemniscal pathway transmit
- touch
- vibration
- proprioception
what is the dorsal column-medial lemiscal pathway made up of
- dorsal white column
- medial lemniscus
list the neurones involved in the dorsal column-medial lemniscal pathway
1st order neurones travel into dorsal white column via FC & FG tracts that synapses in the lower part of the medulla
2nd order neurones travel from medulla and synapses in the thalamus
3rd order neurones travel to specific areas of the cortex
what impulses does the spinothalamic pathway transmit
- pain
- temperature
- coarse touch
- pressure
what tracts is the spinothalamic pathway formed from
- lateral spinothalamic tracts
- ventral spinothalamic tracts
what information is transmitted via the spinocerebellar pathways
- muscle or tendon stretch to the cerebellum
what tracts is the spinocerebellar pathways formed from
- ventral spinocerebellar
- dorsal spinocerebellar
what sensory information is conveyed by the fasciculus cuneatus & fasciculus gracilis tracts and their location
- fine touch
- vibration
- pressure
- proprioception
located in dorsal column
what sensory information is relayed by anterior and posterior spinocerebellar tracts and its location
- unconscious proprioception
located in lateral column
what sensory information is relayed by anterior (ventral) spinothalamic tract and its location
- crude touch
- pressure
located in ventral column
what are the 2 groups of descending pathways
- direct pathways
2. indirect pathways
where do direct pathways originate and where it synapses
primary motor cortex and synapses with lower motor neurones in the ventral horn
list what indirect pathways regulate
- axial muscles to maintain posture
- muscles controlling coarse limb movements
- head, neck and eye movements
list the 4 indirect pathways
- reticulospinal tract
- vestibulospinal tract
- rubrospinal tract
- tectospinal tract
function of reticulospinal tract
controls muscle tone & visceral motor functions
- tract located in ventral and lateral white column
function of vestibulospinal tract + location of tract
maintains balance by varying tone of postural muscles
- tract located in ventral white column
function of rubrospinal tract + location of tract
muscle tone of distal limb movements
- tract located in lateral white column
function of tectospinal tract + location of tract
mediates head movements in response to visual stimuli
list the motor commands relayed by lateral corticospinal tracts and its white column location
- voluntary motor commands that control skeletal muscles
located in lateral white column
list the motor commands relayed by ventral corticospinal tracts and its white column location
- voluntary motor commands that control the skeletal muscles of the axial skeleton, pectoral and pelvic girdle
located in the ventral white column
define paralysis
loss of motor function
define paraesthesias
abnormal sensations and sensory loss
what occurs with damage to lower motor neurones in the ventral horns
flaccid paralysis in affected muscles
list the outcomes of damage to primary motor cortex or upper motor neurone tracts
- spastic paralysis
- spinal reflexes stimulate muscles irregularly
- no voluntary control
