Exam 2 Lecture 1

Question 1

What does the spinal cord connect?

Answer 1

Brain to the body and the body to the brain

Question 2

What vertebrae does the spinal cord end at?

Answer 2

L1-L2

Question 3

Where is the spinal cord located?

Answer 3

• Within the vertebral foramen (canal)
• Posterior to the vertebral bodies

Question 4

Which nervous system is the spinal cord part of and what does this mean for regeneration?

Answer 4

Central Nervous System
-If injured, it CANNOT regenerate

Question 5

What are the two “enlargements” of the spinal cord?

Answer 5

• Cervical region (contains the cervical plexus)
• Lumbar region (contains the lumbar plexus)

Question 6

What is different in regards to the length of the spinal cord in young children vs adults?

Answer 6

• In young children, the spinal cord extends from C1 to nearly the bottom of the sacrum
• As the child grows, the vertebral column grows proportionally more than the spinal cord so the cord is “pulled up” to the adult position

Question 7

Which direction does the spinal cord taper and what is this called?

Answer 7

• Tapers inferiorly
• Conus medullaris

Question 8

What is the role of the Filum Terminale?

Answer 8

Anchors the spinal cord to the sacrum

Question 9

What does a child with a “tethered cord” have?

Answer 9

Scar tissue preventing the spinal cord from moving superiorly

Question 10

What are the four sections of the spinal cord?

Answer 10

• Cervical
• Thoracic
• Lumbar
• Sacral

Question 11

How many spinal cord segments and vertebrae does the cervical region have?

Answer 11

• Spinal cord segments - 8
• Vertebrae - 7

Question 12

How many total spinal cord segments are there and how many are in each region?

Answer 12

30 total

• Cervical = 8
• Thoracic = 12
• Lumbar = 5
• Sacral = 5

Question 13

How many spinal nerves does each spinal cord segment have?

Answer 13

2 (R and L)

Question 14

Where do spinal nerves exit in the cervical region?

Answer 14

SUPERIOR to the corresponding vertebrae

Question 15

Where do spinal nerves exit in the thoracic, lumbar and sacral regions?

Answer 15

INFERIOR to the corresponding vertebrae

Question 16

What is the cauda equina?

Answer 16

• Lumbar and sacral spinal nerve fibers within the vertebral canal, inferior to L2 form this
• Because the spinal cord ends at L2, lumbar and sacral spinal nerves must run inferiorly within the vertebral column before they can exit at their designated vertebrae

Question 17

Where in the spinal cord is the grey matter located?

Answer 17

Internally

Question 18

Where in the spinal cord is the white matter located?

Answer 18

Externally

Question 19

What makes up the grey matter?

Answer 19

• Neuron cell bodies to and from peripheral structures (skin, muscles)
• “Butterfly”

Question 20

What makes up the white matter?

Answer 20

-Nerves connecting body to/from brain

Question 21

As you move inferiorly down the spinal cord, how do the amounts of grey and white matter change?

Answer 21

More grey matter as you move inferiorly, less white matter

-Sacral has the most grey matter, cervical has the least

Question 22

What is grey matter divided into?

Answer 22

Horns

• Ventral/anterior horn
• Lateral horn
• Dorsal/posterior horn

Question 23

What type of neurons does the anterior horn contain and what do they innervate?

Answer 23

Voluntary motor neurons (innervate skeletal muscle)

Question 24

What type of neurons does the lateral horn contain and what do they innervate?

Answer 24

Autonomic motor neurons (innervate smooth and cardiac muscle)

T1-L2 and S2-S4 only

Question 25

What type of neurons does the dorsal root ganglion contain and what do they innervate?

Answer 25

Sensory neurons (innervate skin, subQ tissue, etc)

Question 26

Cross section of spinal cord labeled

Answer 26

Question 27

Spinal nerves emerge from the cord as one of 2 roots:

Answer 27

- Anterior/ventral root: motor axons (voluntary motor neurons, T1-L2 or S3-S4 are autonomic motor neurons) - Posterior/dorsal root: sensory axons

Question 28

Where do dorsal and ventral roots join together and what do they form?

Answer 28

Join together as they penetrate the **DURA MATER** and they form **SPINAL NERVES**

Question 29

Spinal nerves emerging from the spinal cord form \_\_\_\_\_\_\_

Answer 29

Plexuses

Question 30

What are the three major plexuses?

Answer 30

1. **Cervical Plexus (C1-C4)** - phrenic nerve (C2, 3, 4) 2. **Brachial Plexus (C5-T1)** - innervates UEs and skin 1. **Lumbosacral Plexus (L1-S5)** - LEs, femoral and sciatic nerves

Question 31

Axons in the white matter transmit action potentials in which direction?

Answer 31

Superiorly AND Inferiorly

Question 32

What are found within each region of the white matter?

Answer 32

Tracts (bundles of axons) that are organized by their function

Question 33

What is the white matter organized into?

Answer 33

**Regions or columns (funiculus):** - Dorsal/posterior - Lateral - Ventral/anterior

Question 34

Which direction does the descending tract in the white matter convey action potentials?

Answer 34

**INFERIORLY** -Brain to body (move your foot)

Question 35

Which direction does the ascending tract in the white matter relay action potentials?

Answer 35

**SUPERIORLY** -Body to brain (step on something hot)

Question 36

What is a dermatome?

Answer 36

Region of skin innervated by one spinal cord segment (one pair of spinal nerves)

Question 37

What is a myotome?

Answer 37

Functional group of muscles innervated by a spinal cord segment (pair of spinal nerves)

Question 38

What is a first order neuron?

Answer 38

- Part of peripheral nerves - Receptor - Afferent axon - can be myelinated or un-myelinated

Question 39

What is a second order neuron?

Answer 39

- Starts in spinal cord, ends in brain - Part of spinal cord white matter - ascending tracts

Question 40

What is a third order neuron?

Answer 40

- Found in the brain, allows conscious perception of a stimulus - Ends on the post central gyrus (primary somatosensory cortex)