Exam 2 - Lecture 5 Flashcards
CSF circulatory system provides
physical cushion for structures in CNS, and environmental buffer system.
Adjectives for dura layer
Thick, leathery, robust
Dura layer extends to and terminates
where anterior and posterior root come together to form spinal root.
Epidural space
Immediately superficial to dura mater
contains adipose tissue and smaller venous vessels.
Epi means
outside
Lipophilic anesthetics into the epidural space
Adipose tissue might suck up alot of the drug and require a longer onset and will take longer for it to wear off while it seeps out of the fat.
Spinal procedure
Faster onset, needle closer to cord, in subarachnoid space. It makes it risky because if you go too far you can go into the spinal cord.
Safer area to block lower extremity
below spinal cord in the lower back
spinal nerves aren’t packed tight together, whereas spinal cord doesn’t have any movement and can damage it.
Spinal cord stretches from
tail end of brainstem (medulla) to L1
some books say L2, but father schmidt says L1 is more accurate.
Conus Medullaris
Where the spinal cord ends
What is directly underneath conus medullaris?
Spinal nerves
Cervical enlargement
C3-C6, the cord is a bit wider due to extra sensory receptors/motor neurons in upper extremities.
Lumbosacral enlargement
T11-L1, cord is wider due to lots of sensors and muscles in lower extremities.
Structures that cervical enlargement nerves feed into
Brachial plexus
Structures that lumbosacral enlargement nerves feed into
Sciatic nerve and lumbar plexus
Dura layer is continous with nerve roots down to the
Sacrum until it meets the spinal ROOT
Cauda equina
Posterior and anterior spinal roots distal to conus medullaris, safer area for procedures.
Filum Terminale Internum
Functions like ligaments, extension of pia mater, connecting the conus medullaris down to the end of the dural sac.
internum means INSIDE the dural sac.
Dural sac, what is it and where does it start and end?
AKA lumbar cistern, CSF pool at bottom of cord.
From conus medullaris to S2, allowing CSF to still circulate.
Cistern means
Pool or storage area
Filum Terminale Externum
from outside dural sac to the bottom of the coccyx
forms an anchor for the bottom of the dural sac at S2, to keep it from retracting upwards.
Growth of the bones and spine growth rate vs spinal cord
Bones tends to grow faster than the spinal cord lengthens, so there is tension in the cord. The filum Terminale keep it from retracting.
In the adult and newborns, what vertebra is the conus medullaris at?
Adult - L1
Newborn - L3
Lumbar cistern AKA?
Dural sac
CSF on the MRI is
black area surrounding cord
Is there disc between S1 and S2?
No… maybe remnants of it, at most.
Downside to dural sac
Fresh CSF is produced in brain, and new CSF has to slowly work its way down cord via cilia cells, therefore the CSF down here can get stale, and it may be old/last to get replaced. It is a very convenient space to get a CSF sample, but take the results with a grain of salt bc its older.
Good areas for CSF samples or area to give drugs
L3/L4 or L4/L5 interspace, sacral hiatus (less often used), S2 posterior Sacral foramina
Slightly off midline approach with a needle is what degree?
15 degrees
Incomplete fusion of ____ causes you to take a slightly off midline approach
Ligamentum flavum
Arachnoid trabeculae
Pillars/columns that hold up subarachnoid space for blood vessels and CSF to hangout
Epidural area in brain
up against the skull, which has its own arteries and veins to perfuse.
If you fracture the skull, what can happen?
Epidural hematoma, which is an arterial bleed.
If you bleed under the dura layer, what’s it called?
Subdural hematoma, venous bleed.
If you bleed under the arachnoid layer, what’s it called?
Subarachnoid hemorrhage, arterial bleed.
CSF pH
7.31
CSF: Bicarbonate
lower in CSF than blood concentration, making it more acidotic in nature.
CSF: Na+
Similar to blood, 140
CSF: Cl-
Higher than blood, similar to sodium, 140
CSF: K+
40% less than in blood
