Spinal cord Flashcards
Where does the spinal cord terminate? Name of this location?
at L1/L2 as conus medullaris, at some point the spinal cord stops growing as vertebrae continues
dural sac ends at?
L1
the cervical and lumbar enlargements correlate with?
the ventral plexuses
causa equina
bundle of nerve ROOTS that extend inferiorly from the lumbar and sacral levels that branch off the bottom of the spinal cord like a “horse’s tail.”
conus medullaris
conical lower extremity of the spinal cord, WHERE IT ENDS AT L1/L2
What are three distinctive spinal cord regional characteristics?
1) overall size
2) proportion of white matter (axons) to gray mater (Cell bodies)
3) unique features (IML cell column; T1-L2/L3)
gray matter and white matter are made up of?
gray= cell bodies white= axons
higher level regions of spinal cord have more or less white or gray matter?
less gray; higher level is larger with more motor and movement
thickening of gray matter at the end of spinal cord because?
condensation of nerves at conus medullaris; bunch of cell bodies for terminal part of spinal cord
the subdural space is below and above what?
below dura and above arachnoid
3 types of fiber tracts
1) assosciation
2) commissural
3) projection
association fibers
Constricted to the brain on SAME SIDE aka same hemesphere
commissural fibers
connecting 1 hemisphere to the other
projection fibers
any fiber that projects down or up from the cortex
*ALL motor tracts are projections
IMPORTANT association fiber example?
Broca’s area (speech production) to Warnike’s area (speech comprehension)
what is the arcuate fasciculus?Also known as
SLF= superior longitudinal fasciculus
**connects Broca’s area (speech production) to Warnike’s area (speech comprehension)
What is corpus callosum?
a broad band of nerve fibers joining the two hemispheres of the brain
All tracts are made up of what type of fier?
projection
what is corona radiata?
is a white matter sheet that continues ventrally as the internal capsule and dorsally as the centrum semiovale. This sheet of both ascending and descending axons carries most of the neural traffic from and to the cerebral cortex
what are the 3 sections of projection fibers?
1) posterior funiculus
2) lateral funiculus
3) anterior funiculus
the posterior funiculus is completly made up of?
sensory tracts
the lateral and anterier supplied by?
by the anterior spinal artery
the posterior funiculus is supplied by?
posterior spinal artery
the lateral and anterior funiculi are made up of?
sensory and motor tracts
all motor information comes from?
pre-central gyruc
motor and sensory tracts run through white or gray matter?
white
axons of upper motor neuron that go down to synapse on the lower motor neuron, which would be in the ___horn since we’re down in the spinal cord
ventral
what are the 2 divisions of motor tracts we are going to learn?
they are corticospinal tracts
1) lateral corticopinal tract
2) anterior corticospinal tract
* *and has an associated tract called corticobulbar
lateral corticopinal tract destined for?
extremities mainly hands/feet; go to OPPOSITE SIDE
anterior corticospinal tract destined for?
postural muscles aka trunk; stay on SAME SIDE
What tract STAYS on the same side of body? which one doesn’t?
lateral corticopinal tract= OPPOSITE
anterior corticospinal tract= SAME
___% of corticol spinal tract is lateral?
90% is lateral because there is SO MUCH info going to the hands and feet
why are the corticospinal tracts named the way they are?
lateral is in the lateral funiculus
anterior is in the anterior funiculus
the corticospinal tract and what other tract start together and then split?
corticobulbar (split in bulb and goes to brain)
upper motor neuron (UMN) is in the?
pre-central gyrus
voluntary motor route (to leave brain) for corticospinal
1) cell bodies in pre-central gyrus
2) axons descend thru internal capsule
3) cerebral peduncle and pons
4) pyramids of medulla
***cross to opposite at decussation of pyramids
5) axons continue descending until the hit lower motor neuron (LMN)
6a option) CN nuclei (LMN) in brain-stem
6b option) LMN in ventral horn and leaves through other terminal branches
internal capsule is a bundle of? Located where?
bundle of white mater that is running in between the thalamus and basal ganglia nuclei
all voluntary motor is leaving through?
the same route
what does cerebral peduncle?
connects cerebrum to brain-stem
define ipsilateral
belonging to or occurring on the same side of the body
define contralateral
relating to or denoting the side of the body opposite to that on which a particular structure or condition occurs
any lesion that happens in the left cerebral peduncle affects?
right side motor
any lesion that occurs in left ventral horn of T2 affects?
left side for motor
UMN in one precentral gyrus will synapse on?
CONTRALATERAL LMN
what happns to 10% of axons that DON’T decussate?
they will continue as the anterior corticospinal tract along the ipsilateral side
each motor tract has how many neurons?
2
where does upper and lower motor neuron reside?
UMN= within precentral gyrus/motor cortex LMN= within ventral horn of wherever signal terminates to the extremities at
What does the UMN synapse on if it goes to brain-stem?
cranial nerve nucleii
corticobulbar tract is voluntary control of?
skeletal muscle of head and neck through cranial nerve.
NOT eye movements- extraoccular muscles have a different tract
corticobulbar tract route
UMN follows same course: precentral gyrus - internal capsule -cerebralpeduncle - synapse on cranial nerve motor nuclei throughout midrain/pons/medulla
most cranial nerve nucleireceive bilateral input; what are the 4 big ones?
1) trigeminal
2) hypoglossal
3) nucleus ambiguos (CN 9 and 10)
4) facial (partially)
* 5, 7, 9, 10, 12 are all bilateral
what CN receivese unilateral input?
unilateral=ipsilateral =CN 11
why do unilateral corticobulbar tract lesions produceno remarkable clinical effect on head and neck muscles?
due primarily to bilateral corticobulbar input
*there are exceptions
A lesion to the peripheral nerve results in?
loss of function (just like in spinal nerves)
