Sensory system, spinal cord and brainstem L6 Flashcards
How long is the spinal cord
42-45
What percentage of vertebral column is the spinal cord
upper 2/3
Where does the spinal cord extend from
foramen magnum–> L1/L2
Enlargements of the spinal cord=
cervical and lumbosacral
A spinal segment=
1 spinal nerve coming out
Order of the spinal cord and number of nerves
Cervical 8 Thoracic 12 Lumbar 5 Sacral 5 coccyx 1
Ventral root=
purely motor (efferent)
Dorsal root=
Purely sensory (afferent)
Spinal nerve=
dorsal + ventral roots
Where does the spinal nerve lie
intervertebral foramen
Everything from the spinal cord distal is___
mixed
Reason the spinal cord doesn’t extend all the way through the vertebral column
Developmental–> in utero
At what stage of pregnancy does the the vertebral column grow longer than the cord
past three months
What is the tapering down of the spinal cord called
conus medullaris
Where is the conus medullaris found
L1/L2 (lower in child)
What is the cauda equina
a bunch of roots sitting in the subarachnoid space
What does the cauda equina NOT contain
spinal nerves
What is the filum terminal
continuation of the pia matter that continues down to the bottom end of the subarachnoid space, containing the cauda equina
What is the lumbar cistern
cerebrospinal fluid creating an anatomical lake without much neuro tissue
What does the lumbar cistern contain
Filum terminal
nerve roots of the cauda equina
Where to take lumbar tabs from
L3/L4 or L4/L5
What happens to the amount of white matter as you travel down the spinal cord
decreases
What is a commissure
an axon that crosses one side of the CNS to the other
Deccussation=
crossing over the midline
Ipsilateral=
on the same same
Contralateral=
on the opposite side
3 neurons of ascending pathways
First order
second order
third order
First order neurons=
stimuli from external receptors –> cell bodies in dorsal roots
Second order neurons=
spinal cord & brainstem tracts
Decussate (cross midline)
Third order neurons=
thalamus via internal capsule
Which tracts are conscious perception;
dorsal columns
spinothalamic
what tratcs are unconscious perception;
spinocerebellar *
spinotectal
spinoreticular
Spino-olivary
Dorsal columns enter
via dorsal roots
dorsal columns ascend
ipsilateral
Dorsal columns synapse at the brain stem with
gracile and cuneate nuclei in medulla oblangata
Fibres that run to the gracile nuclei form the_____
fasciculus gracilis (medial)
Which area of the body does the fasciculus gracilis fibres represent
lower 1/2 (most medial fibres)
Fibres that run to the cuneate nuclei form the ______
Fasciculus cuneatus (lateral)
Fasciculus cuneatus fibres represent what area of the body
upper 1/2 of the body (lateral fibres)
Dorsal root second order neurons start in the;
Nucleus (cuneate or gracile),
Dorsal root second order decussate in____
The brain stem
What tract do the dorsal root second order neurons form after the brain stem
medial lemniscus
Where does the medial lemniscus tract run to
the contralateral thalamus
Where do the third order neurons of the DCML run
from the contralateral thalamus to the corresponding part of the cerebral cortex
DCML=
Dorsal column medial lemniscus
What does the DCML sense
dicrimminative aspects of tactile and proprioceptive sensation; fine touch pressure vibration conscious proprioception
spinothalamic tract first order neurons; (2 part story)
come into the spinal cord and synapse with the dorsolateral fasciculus, then rises up one or 2 segments ipsilaterally
spinothalamic tract second order;
decussate straight away and ascend contralaterally (anterior to the ventral horn)
What does the spinothalamic tract form in the brainstem
a spinal lemiscus (which stays on the same side)
What does the anterior spinothalamic tract sense
crude touch
What does the lateral spinothalamic tract sense
pain and temperature
Spinocerebellar=
unconcious proprioception
What does the dorsal spinocerebellar tract sense from
muscle spindles, golgi tendon organs, touch & pressure receptors
The dorsal spinocerebellar tract enters at ?
T1-T2
where do the 2nd order tracts in the dorsal spinocerebellar tract start and raise
nucleus dorsalis and raise ipsilaterally to the cerebellum (not thalamus)
What is the ventral spinocerebellar tract used to sense
movement control
Difference of the ventral and dorsal spinocerebellar tracts
the ventral decussates –> contralateral ascent
