Unit 5: spinal cord & meninges

Question 1

name the 3 layers of the meninges from most deep to most superficial

Answer 1

1. pia mater
2. arachnoid mater
3. dura mater

Question 2

why is the subdural space a “potential space?”

Answer 2

there’s not much of a “space” between the dura and the arachnoid mater

Question 3

where do the meninges terminate on the spinal nerves?

Answer 3

up until right after the anterior root and the posterior root ganglion

Question 4

what comprises the epidural space?

Answer 4

adipose tissues
blood vessels

Question 5

why would lipid soluble drugs given via epidural have a longer onset effect time?

Answer 5

because lipophilic drugs will “soak” into the adipose tissues in the epidural space; additionally, the lipophilic drug effect will also linger for a while after the epidural catheter is removed for the same reason

Question 6

where is the optimal area to administer a spinal block without injuring the spinal cord?

Answer 6

more inferior to L1/conus meddularis (where the spinal cord terminates)

Question 7

where is the cervical enlargement on the spinal cord located?

what is meant by “cervical enlargement”?

Answer 7

the cervical enlargement is located at C3-C6

because we have a lot of sensory input and motor control in our upper extremities, there is a lot of innervation in these locations as well

Question 8

where is the lumbar enlargment located on the spinal cord?

Answer 8

lower limbs
(T11-L1)

Question 9

what does the nerve collection after the cervical enlargement called? where is it found?

Answer 9

the brachial plexus
in the shoulder

Question 10

what is the nerve collection after the lumbar enlargement called?

Answer 10

the lumbar plexus + the sciatic nerve

Question 11

in the lower spinal cord, where does the dural meningeal layer terminate?

Answer 11

the dural layer is continous throughout the spinal cord until the nerve roots terminate at the sacrum

Question 12

what is the Conus Medullaris?

Answer 12

the end of the spinal cord in the sacral region

after L1 in adults

Question 13

what is the Cauda Equina?

Answer 13

“horse’s tail”
this is a collection of posterior and anterior spinal roots after the Conus Medullaris

these anterior/posterior spinal roots have not yet combined to form the spinal nerve

Question 14

differentiate filum terminale internum vs externum

Answer 14

filum terminale internum is IN the dural sac (lumbar cistern) and this is a ligament that anchors the conus medullaris to the end of the dural sac

the filum terminale externum is OUTSIDE the dural sac and it is the ligament that anchors the spinal cord at the end of the dural sac to the end of the coccyx

Question 15

at which sacral vertebra is the filum terminale externum located?

Answer 15

S2

Question 16

what is the dural sac/lumbar cistern filled with?

Answer 16

CSF

Question 17

where does the conus medullaris terminate in adulthood? as a newborn?

Answer 17

L1 in the adult

L3 in a newborn

bone grows faster than the spinal cord lengthens, which is why the cord will shift up a couple of levels as we mature

Question 18

if you were to gather a CSF sample via lumbar puncture, why can the sample cause innaccurate results?

Answer 18

the CSF can get “stale” in the dural sac because it is very far from the source (the brain) and does not get recirculated well in the sac

Question 19

between which lumbar/sacral vertebra would be an optimal place to sample CSF or to give epidural/spinal anesthesia?

Answer 19

between L3/L4
between L4/L5
S2 (for local anesthetic)
spinal hiatus

Question 20

if a patient has an incomplete fusion of their ligamentum flava, what is the best angle to approach when doing an epidural/spinal?

Answer 20

slightly off-midline – to avoid puncturing the spinal cord