Spinal Cord Anatomy

Question 1

How many pairs of spinal nerves?

Answer 1

31

Question 2

How many cervical spinal nerves?

Answer 2

8

Question 3

How many thoracic spinal nerves?

Answer 3

12

Question 4

How many lumbar spinal nerves?

Answer 4

5

Question 5

How many sacral spinal nerves?

Answer 5

5

Question 6

How many coccygeal?

Answer 6

1

Question 7

Which nerves exit ABOVE corresponding vertebra?

Answer 7

C1-C7.

Question 8

Where does C8 exit?

Answer 8

Below C7, above T1.

Question 9

Where do T1 and below exit?

Answer 9

Below corresponding vertebrae.

Question 10

Where does the spinal cord end?

Answer 10

L1-L2.

Question 11

Where does the subarachnoid space extend to?

Answer 11

Lower border of S2.

Question 12

Where is LP performed?

Answer 12

Between L3-L4 or L4-L5.

Question 13

What is herniating through what w/ a vertebral disc herniation?

Answer 13

Nucleus pulposus (soft central disc) hernates through annulus fibrosus (outer ring).

Question 14

Most common site of vertebral disc herniation?

Answer 14

Posteriorly at L4-L5 or L5-S1.

Question 15

What tracts of the spinal cord travel in the 11:00-1:00 regions?

Answer 15

Dorsal columns

Question 16

What tract of the spinal cord travels from 2:00-3:00, or 9:00-10:00?

Answer 16

Lateral corticospinal tract

Question 17

What tract of the spinal cord travels from 3PM to 6PM? (and 6PM to 9PM?)

Answer 17

Lateral spinothalamic tract, at bottom there’s Anterior spinalthalamic tract.

Question 18

What is at 6PM of the spinal cord?

Answer 18

Anterior corticospinal tract.

Question 19

What is the organization of the lateral corticospinal tracts and lateral spinothalamic tracts?

Answer 19

Cervical is Central, Lateral is Legs/Lumbosacral.

Question 20

What is the organization of the dorsal columns?

Answer 20

Opposite: Lower inside, upper outside.

Question 21

What are the two parts of the dorsal columns?

Answer 21

Fasciculus gracilis, fasciculus cuneatus

Question 22

What does the fasciculus gracilus contain?

Answer 22

Lower body. (Ass in the Grass). Cuneatus has upper body.

Question 23

What are the dorsal columns responsible for?

Answer 23

Pressure, vibration, fine touch, and proprioception.

Question 24

What are the lateral spinothalamic tracts responsible for?

Answer 24

Pain and temperature.

Question 25

What are the anterior spinothalamic tracts responsible for?

Answer 25

Crude touch and pressure.

Question 26

What are the corticospinal tracts responsible for?

Answer 26

Voluntary movement of contralateral limbs.

Question 27

What is the 1st order neuron of the dorsal columns?

Answer 27

Sensory nerve endings --> cell body in dorsal root ganglion --> enters spinal cord, ascends ipsilaterally in dorsal column.

Question 28

Where does the 1st order neuron of the dorsal column synapse?

Answer 28

Ipsilateral nucleus cuneatus or gracilus - medulla.

Question 29

What is the second order neuron of the dorsal column?

Answer 29

Decussates in the medulla, ascends contralaterally in medial lemniscus.

Question 30

Where does the second order neuron of the dorsal column synapse?

Answer 30

VPL of the thalamus.

Question 31

Where does the 3rd order neuron of the dorsal column go?

Answer 31

Sensory cortex.

Question 32

What is the 1st order neuron of the spinothalamic tract?

Answer 32

Sensory nerve ending (A-Delt and C fibers) - cell body in dorsal root ganglion --> enters spinal cord.

Question 33

Where does the 1st order neuron of the spinothalamic tract synapse?

Answer 33

Ipsilateral gray matter of the spinal cord

Question 34

What does the second order neuron of the spinothalamic tract do?

Answer 34

Decussates at anterior white commissure --> ascends contralaterally.

Question 35

Where does the second order neuron of the spinothalamic tract synapse?

Answer 35

VPL, thalamus.

Question 36

Where does the third order neuron of the spinothalamic tract go?

Answer 36

Sensory cortex

Question 37

What is the 1st order neuron of the corticospinal tract?

Answer 37

UMN: Cell body in Primary motor cortex. Descends ipsilaterally through internal capsule, most fibers decussate at caudal medulla (pyramidal) --> descends contralaterally

Question 38

Where does the 1st order neuron of the corticospinal tract synpase?

Answer 38

Cell body of anterior horn in the spinal cord

Question 39

What is the second order neuron of the corticospinal tract?

Answer 39

LMN: leaves spinal cord.

Question 40

Where does the second order neuron of the corticospinal tract synpase?

Answer 40

NMJ.