control term two (1) Flashcards
how many vertebrae are there?
7 cervical 12 thoracic 5 lumbar 5 sacral (fused) 1 coccygeal (made of 4 fused segments)
30 total
(33 if include different segments of coccyx)
how many spinal cord segments are there?
31 (one more than no. vertebrae
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
what doe each spinal cord segment give rise to?
a PAIR of spinal nerves
how are the spinal nerves named?
cervical region: spinal nerve goes ABOVE vertebrae (ie C1 is above c1 vertebrae)
below cervical region: spinal nerve goes BELOW vertebrae (ie T1 is below T1 vertebrae)
what spinal nerve comes out above T1 vertebrae
C8
where are the 2 enlargements of the spinal cord?
cervical enlargement
lumbosacral enlargement
what is the most inferior tip of the spinal cord called? and at what vertebral level does it occur?
conus medullaris (medullary cone)
vertebrae L2
what is the structure that connects the end of the spinal cord to the coccyx?
filum terminale
extension of pia matter
what are the 2 differences between the meninges that surround the spinal cord and the ones that surround the brain?
surrounding spinal cord: only ONE layer of dura matter (brain has 2)
- spinal dura is a continuation of the meningeal layer (layer closest to brain/spinal cord)
spinal cord has denticulate ligaments (brain doesn’t)
what are denticulate ligaments?
little extensions of PIA matter which extend laterally, anchoring spinal cord to vertebral column
- prevent spinal cord rotating within vertebral column
- have about 21/22 of them down length of cord
how does the CSF from the brain enter the subarachnoid space surrounding the spinal cord?
by leaving the ventricular system via the lateral and median apetures
what are the 2 layers of dura matter that surround the brain? which is closest to the brain? where do they go when the brain –> spinal cord?
meningeal layer
- closest to brain
- surrounds spinal cord
periosteal layer
- closest to skull
- fold around onto superficial surface of skull
nb also have periosteal dura surrounding vertebrae
what is the potential space between the arachnoid matter and the dura matter?
subdural space
where is the epidural space?
outside (superficial to) the dura
aka extradural space
where is anaesthetic injected into for a spinal block?
subarachnoid space
what are the nerves which fill the vertebral column called inferior to the end of the spinal cord? at what levels of vertebrae do these arise?
cauda equine
“horses tail”
L2-S2
what is the area in the vertebral column called inferior to the spinal cord (from L2 down)?
what 3 things are found in this space?
lumbar cistern
- CSF
- Filum terminale
- cauda equina
what is a lumbar puncture? and where is it performed?
collection of CSF (via a needle) for testing
lumbar cisterne
so no risk of puncturing spinal cord
why does the spinal cord not terminate at the coccyx?
itdid, in the foetus, but then the foetal vertebral column grows faster than the spinal cord and so it looks like spinal cord has shrunk
describe the blood supply of the spinal cord
the 2 vertebral arteries each give off a branch anteriorly which combine to form ONE ANTERIOR SPINAL ARTERY, they both also give of a branch posteriorly, TWO POSTERIOR SPINAL ARTERIES
these arteries are supported by SEGMENTAL MEDULARY and RADICULAR arteries along length of cord
what 4 sections of white matter are in the spinal cord?
- dorsal white column
- lateral white column
- ventral white column
- ventral white commissure
what 4 sections of grey matter are in the spinal cord?
- dorsal grey horn
- lateral grey horn (only sometimes!!)
- ventral grey horn
- dorsal grey commissure
what type of fibres do dorsal + ventral roots tend to carry?
dorsal - sensory
ventral - motor
where do you get lateral grey horns? why here?
T1-L2
S2-S4
the lateral grey horn is full of AUTONOMIC cell bodies so you get them where there is a lot of autonomic viscera (ie in thorax and pelvis)