spinal cord function adn dysfunction Flashcards
summarise the spinal cord segments
31 spinal segments
31 pairs of nerves - 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal - leave the vertebral column through intervertebral foramen
why are there cervical and lumber enlargements *
for innervation of the limbs
there are many more neurons in the cord at these points
what does the cervical enlargement innervate and what spinal segments are involved *
upper limbs
C3-T1
what does the lumbar enlargement innervate and what spinal segments are involved *
upper limbs
L1-S3
describe at what level the nerves leave the vertebral column *
C1-C7 nerve leave above the relevant vertebrae,
C8 leaves between C7 and T1 vertebrae, every nerve after that leaves after the relevant vertebrae
describe the discrepancy between the spinal levels and the vertebral levels *
each has the same number as segments - spinal cord segment is shorter
therefore coccygeal segment of spinal cord is at the 2nd lumber vertebrae
where the nerve emerges from the cord is different from where it emerges from the vertebrae - the nerves get more angled lower down
what is the clinical relevance of the discrepancy between the spinal and vertebral levels *
the effect of an injury depends on the spinal level and the vertebral level that it occurs
describe the meningeal coverings *
dura mater - continuous with inner sheet of dura in cranium, forms dural sac, extends to S2, hard
arachnoid mater - ballooned up against dura, spider like
pia mater - adheres tightly to the surface of the spinal cord - the filum terminale is an extension of the pia mater - tethering the spinal cord to the sacrum
describe the epidural space *
true space - between dura and periosteum, filled with fat and venous plexus
describe the subarachnoid space *
filled with CSF
continuous with subarachnoid space of cranium
describe the posterior root *
carries sensory info
cell bodies in spinal ganglion
enters the spinal cord in the posterolateral sulcus
describe the spinal ganglion *
contains the nerve cell bodies or primary sensory afferents, pseudounipolar neurons - there are no synapses
describe the anterior root *
carries motor info, exits spinal cord through anterolateral sulcus
describe the denticulate ligament
extensions of pia - anchor the spinal cord to the dura
lateral denticulate ligaments separate posterior and anterior roots
comparison between the meninges in the brain and in the vertebral column *
no space between the dura and the skull, but tehre is space between the dura and the vertebral column - useful to inject anaesthetics into the epidural space in the spine instead of using a general anaesthetic - eg in C section
also because the spinal cord ends at L2 - unlikely to be damaged
also can take a lumbar puncture of subarchnoid space- sample the CSF that flows down the spinal canal - can see what is happening in brain and if there is a sign of infection and add anaesthetics here
also can add spinal blocks into subarachnoid space - when you know the dose you will need
where are the ascending and descending tracts in the spinal cord *
in the white matter
define dermatome
area of skin supplied by one single spinal nerve or spinal segment
define myotome
collection of muscles innervated by single spinal nerve or segment
what are rootlets
they come from the horns of grey matter and join to form roots
define roots *
roots only have either sensory or motor fibres
they mix with the other type of root (motor/sensory) to form the spinal nerve
a bundle of nerve fibres at its emergence from the spinal cord
what is the spinal nerve *
mix of nerves - going into dorsal horn and out of ventral horn
what is a rami *
have anterior and posterior rami mix of sensory and motor branches of the spinal nerve anterior innervates most of body posterior smaller, innervate skin and muscles of back