Lecture 9/10: Spinal Cord and Meninges

Question 1

What is the purpose of the spinal meninges?

Answer 1

• Goal of meninges is to surround CNS with controlled environment
• Buffer/tightly regulate fluid surrounding CNS reduces potential problems

Question 2

What are the 3 layers of connective tissue of the CNS?

Answer 2

Pia mater, arachnoid mater, and dura mater

Question 3

The pia mater is the

Answer 3

1st layer stuck directly to neurons/glial cells

Question 4

The arachnoid mater is the

Answer 4

2nd layer - more superficial layer to pia and large blood vessels that perfuse CNS (spinal arteries and veins - below pia, above arachnoid layer)
- fairly thin/translucent layer

Question 5

What is in the subarachnoid space?

Answer 5

CSF and blood vessels

Question 6

The dura mater is the

Answer 6

outer layer, tough/robust, largest

Question 7

What is the subdural space? Is there anything there?

Answer 7

The potential space between the arachnoid and dura layers, but nothing is really there in the spinal cord

Question 8

The _____ is the space immediately superficial to dural layer

Answer 8

epidural space

Question 9

What is in the epidural space?

Answer 9

Adipose tissue (yellow) and venous blood vessels (blue)

Question 10

Where are epidurals usually injected?

Answer 10

In the epidural space - shuts down AP that is being transmitted through that area of the cord

Question 11

How does a lipophilic anesthetic injected as an epidural work?

Answer 11

Epidural space has a lot of fat, so the lipophilic anesthetics will have a longer onset because a lot is taken up by adipose, which also means it takes longer for drugs to wear off (spongy)

Question 12

What are the circulatory systems for the CNS?

Answer 12

CV system helps perfuse CNS
CSF circulatory system - makes CSF

Question 13

The ____ provides a physical cushion for the physical structures in the nervous system

Answer 13

CSF - helps resist damage

Question 14

The majority of the CNS is made up of the _____ layer

Answer 14

Dura

Question 15

What would be the source of a subarachnoid hemorrhage?

Answer 15

The blood vessels below the arachnoid mater

Question 16

The ____ is the dividing point between the PNS and CNS

Answer 16

Spinal nerves - meninges cover up CNS or until spinal nerves

Question 17

If someone is getting knee surgery and doesn’t want anesthesia, they could get an ______

Answer 17

epidural - shuts down motor and pain

Question 18

A spinal procedure in the subarachnoid space would be ______

Answer 18

More risky because underneath dura and arachnoid layers - could puncture the spinal cord
Would have faster onset

Question 19

The best place to do a spinal procedure is where there is no _____

Answer 19

spinal cord - safest in lower back
- spinal nerves can move out of the way if you go too deep, but the spinal cord can’t

Question 20

Where does the spinal cord start and end?

Answer 20

Medulla (brainstem) → L1

Question 21

What is the end of the spinal cord called?

Answer 21

Conus medullaris

Question 22

What does cauda equina mean?

Answer 22

Horse’s tail

Question 23

What is the cauda equina?

Answer 23

Where the inferior nerve roots exit the spine (posterior and anterior) - roots that haven’t yet combined to form the spinal nerves

Question 24

What are the 2 enlargements in the spinal cord? Where are they located?

Answer 24

Cervical - upper limbs (C3-C6)
Lumbar - lower limbs (T11-L1)

Question 25

The cervical enlargement feeds into the _____

Answer 25

Brachial plexus

Question 26

The lumbar enlargement feeds into the _____

Answer 26

lumbar plexus and sciatic nerve

Question 27

______ is the connective tissue after conus medullaris in sacral canal down to the dural sac

Answer 27

Filum terminale internum - red line in pic

Question 28

What is the function of the filum terminale internum?

Answer 28

Anchors cord to structures in spine - connects cord at conus medullaris to end of dural sac - internum = in the dural sac

Question 29

What is the CSF-filled structure that extends past the conus medullaris? Where does it extend to?

Answer 29

The dural sac aka lumbar cistern - extends to S2, until the cauda equina exits the lower part of the spine

Question 30

A good place to aim a spinal needle is

Answer 30

Below the conus medullaris, and dural sac

Question 31

What is the connective tissue inferior to f.t. internum? What is its function?

Answer 31

Filum terminale externum - Ligament coming out of dural sac down to the coccyx - Anchor that holds the bottom of the dural sac to S2 - blue line in pic

Question 32

What are the anchors that keep the spinal cord from retracting up during growth?

Answer 32

Filum terminale internum and externum - bone grows faster than spinal cord lengthens → tension

Question 33

Compare the location of the conus medullaris of an adult to a newborn

Answer 33

- Adult - cord ends at L1 - Newborn - cord ends at L3

Question 34

What are the structures you can see in this CT?

Answer 34

Cervical/thoracic CT 1. Nuchal ligament 2. Supra-spinous ligament underneath fat layer 3. Cord is narrow, has black areas immediately outside of cord → CSF 4. Spinous processes angled inferiorly in T-spine

Question 35

Where is a good place to get a sample of CSF? What's the catch?

Answer 35

Lumbar cistern - sample isn’t fresh so take results with a grain of salt because older CSF Circulatory system of CSF ends at the end of the cord

Question 36

What are the structures you can see in this CT?

Answer 36

Thoracolumbar CT 1. Intervertebral discs 2. Remnants of intervertebral disc between S1 and S2 3. lumbar cistern 4. Large spinous processes but have space for needle

Question 37

What are the potential access points for a CSF sample/drug administration in the lower spine?

Answer 37

L2-3 L3-4 L4-5 Sacral hiatus - not used frequently Posterior sacral foramina located at S2

Question 38

What angle would be "slightly off midline" for a spinal?

Answer 38

15-degree angle

Question 39

Incomplete fusion of which ligament can make midline approach with spinal be higher risk for damaging spinal cord?

Answer 39

Ligmentum flavum

Question 40

How does the ligmentum flavum differ in composition from the rest of spinal ligaments?

Answer 40

Ligmentum flavum has higher composition of elastic fibers than collagen fibers.