M7: Bonus Questions Meninges, Spinal Cord, Roots, Gray vs White Matter

Question 1

The dorsal (posterior) root is responsible for what kind of information?

Answer 1

sensory information or afferent

Question 2

What is the ventral (anterior) root responsible for?

Answer 2

motor function or efferent

Question 3

How many layers of the spinal meninges are there? Name them.

Answer 3

There are three: the Dura Mater, Arachnoid Mater, and Pia Mater

Question 4

Which layer of the meninges is described as the tough and inflexible outermost layer?

Answer 4

Dura Mater (or pachymeninx)

Question 5

The dura mater extends past the spinal cord to about the ______ ______ vertebra

Answer 5

the second sacral vertebra or “S2”

Question 6

What layer of the meninges is a delicate, spiderweb-like layer of tissue between the dura mater and pia mater and creates a subarachnoid space?

Answer 6

arachnoid mater

Question 7

Which layer of the meninges is a thin, mesh-like layer of mater that closely envelops the entire surface of the brain and spinal cord?

Answer 7

Pia Mater

Question 8

The ___________ mater is a delicate, spiderweb-like layer of tissue that is between the dura and pia layers and creates a __________ __________ (Common Site for Spinal Punctures)

Answer 8

Answers: The arachnoid mater is a delicate, spiderweb-like layer of tissue that is between the dura and pia layers and creates a subarachnoid space (Common Site for Spinal Punctures)

• Bonus note you don’t need to know but might help: (arachnida* means “spider”) and the subarachnoid space is beneath the spiderweb-like layer of tissue of the arachnoid membrane, hence “sub-arachnoid space”

Question 9

Which layer of the meninges closely envelops the entire surface of the brain and spinal cord?

Answer 9

Pia Mater

Question 10

What is meningitis?

Answer 10

a medical condition caused by inflammation of the meninges

Note: meninges are the protective membranes covering the brain and spinal cord

Question 11

Meningitis (inflammation of the menginges) is potentially life threatening due to the inflammation’s proximity to what major structures?

Answer 11

the brain and spinal cord

Question 12

The posterior root is also known as the _____ root

Answer 12

dorsal root

Question 13

Which type of matter contains large numbers of myelinated and unmyelinated axons?

Choose One:

White Matter

Grey Matter

Answer 13

Answer: White Matter

Question 14

Which type of matter is dominated by cell bodies of neurons, neuroglia, and unmyelinated axons?

Choose One:

White Matter

Grey Matter

Answer 14

Grey Matter

Question 15

What feature of vertebrae does the spinal cord run through?

Answer 15

vertebral foramen

Question 16

The anterior root is also known as the _____ root

Answer 16

ventral root

Question 17

Identify the following structures labeled #1, #2, and #3. (Click on image to enlarge)

Answer 17

1: Dorsal Root (aka Posterior Root)

Question 18

Where does the spinal cord typically end?

Answer 18

Answer: L1-L2 junction

• Note: L1 stands for the first lumbar vertebrae and L2 stands for the second lumbar vertebrae.*
• Bonus note not directly in lecture but might be helpful/interesting connection:*

Lumbar punctures are useful diagnostic tests for diseases like menginitis, which involve inserting the needle between two lumbar vertebrae, most commonly L3-L4 or L4-L5. This makes sense because the spinal cord is absent there and the delicate nerve roots drift away from the point of needle insertion, so there is little or no danger of damaging the cord. If you did it higher, say between thoracic vertebrae or even L1-L2, you’d hit or risk hitting the spinal cord and/or nerve roots.

Question 19

How long is the average adult spinal cord?

Answer 19

45 cm or 18 inches

Question 20

1. At what vertebral level or junction does the adult spinal cord typically end?
2. At what vertebral level or junction does the dura mater typically extend to?

Answer 20

1. The spinal cord typically ends around the L1-L2 junction (between L1 and L2)
2. The dura mater typically extends to the level of S2 or the second sacral vertebra.