Chapter 13 Part 1

Question 1

Ventral Root

Answer 1

Contains efferent axons, including axons that innervate skeletal muscle.

Question 2

Dorsal Root

Answer 2

Contains sensory axons that connect with a single segment of the spinal cord.

Question 3

Spinal Nerve

Answer 3

Contains all of the motor, sensory, and autonomic axons of a single spinal segment.

Question 4

Dorsal root ganglion

Answer 4

Contains cell bodies of primary sensory neurons.

Question 5

Tract cell

Answer 5

Neuron with a long axon that conveys information from the spinal cord to the brain.

Question 6

Propriospinal neuron

Answer 6

Neuron that begins and ends within the spinal cord.

Question 7

Doral ramus

Answer 7

Innervates paravertebral muscles, posterior vertebral structures, and overlying cutaneous areas.

Question 8

What is a significant feature of the spinal cord?

Answer 8

segmental organization

Question 9

How is each segment of the cord connected to a specific region of the body?

Answer 9

by axons traveling through a pair of spinal nerves.

Question 10

Where are spinal nerve found in the cervical region?

Answer 10

above the corresponding vertebrae, except the eighth spinal nerve

Question 11

Where do spinal nerves lie in the remainder of the cord?

Answer 11

below the corresponding vertebrae

Question 12

What does white matter surround?

Answer 12

gray matter

Question 13

What does what matter do?

Answer 13

contains axons that link the cord with the brain

Question 14

How is gray matter classified?

Answer 14

10 histologic regions, called Rexed’s laminae

Question 15

What do Laminae I and II do?

Answer 15

process information about pain

Question 16

What does the dorsal horn do?

Answer 16

processes sensory information

Question 17

What does the lateral horn do?

Answer 17

processes autonomic information, and present at T1-L2 segments

Question 18

What does the ventral horn do?

Answer 18

processes motor information

Question 19

What are meninges?

Answer 19

layers of connective tissue that surround the spinal cord, and
are continuous with the meninges surrounding the brain

Question 20

What is pia matter?

Answer 20

closely adheres to the spinal cord surface

Question 21

What is arachnoid?

Answer 21

separated from the pia by cerebrospinal fluid in the subarachnoid space

Question 22

What is dura?

Answer 22

tough, outer laye

Question 23

What is the function of the spinal cord?

Answer 23

exchange information with brain and peripheral nerve structures and other segments

Question 24

What do interneuronal circuits do?

Answer 24

integrate the activity from all sources and adjust output of lower motor neurons

Question 25

What do interneurons do?

Answer 25

coordinate activity in all the muscles when a limb moves

Question 26

What are stepping pattern generators?

Answer 26

Are adaptable neural networks that produce rhythmic output

Question 27

How do stepping pattern generators work?

Answer 27

Contribute to stepping by activating LMNs, eliciting alternating flexion and extension at the hips and knees

Question 28

How are stepping pattern generators activated?

Answer 28

when the person voluntarily sends signals from the brain to the CPGs in the spinal cord to initiate walking

Question 29

Rexed lamina I (marginal zone)

Answer 29

Project neurons that receive input form small diameter afferents; once source of anteriolateral system projections

Question 30

Rexed lamina II (substantia gelatinosa)

Answer 30

interneurons that receive input mainly from small diameter afferents; integrates feedforward and feeback inputs that modulate pain transmission

Question 31

Rexed lamina III/IV (nucleus proprius)

Answer 31

interneurons that integrate inputs from small and large diameter afferents

Question 32

Rexed lamina V/VI (base of dorsal horn)

Answer 32

projection neurons that receive input from both large and small diameter affterents and spinal interneurons; another source of anterolateral system projections

Question 33

Rexed lamina VII (intermediate gray)

Answer 33

interneurons that communicate between dorsal and ventral horns; includes dorsal nucleus of Clarke

Question 34

Rexed lamina VIII (motor interneurons)

Answer 34

interneurons in the medial aspect of ventral horn that coordinate the activities of lower motor neurons

Question 35

Rexed lamina IX (motor neuron columns)

Answer 35

columns of lower motor neurons that govern limb musculature

Question 36

Rezed lamina X (central gray)

Answer 36

interneurons surrounding the rudiment of the central cord

Question 37

What do interneurons in inhibited circuits do?

Answer 37

contribute to spinal cord motor coordination

Question 38

What do inhibitory interneurons provide:

Answer 38

Reciprocal inhibition | Recurrent inhibition

Question 39

What does reciprocal inhibition do?

Answer 39

Decreases activity in antagonist when an agonist is active, allowing the agonist to act unoppose separates muscles into agonists and antagonists

Question 40

What is recurrent inhibition?

Answer 40

Effects opposite to reciprocal inhibition: inhibition of agonists and synergists, disinhibition of antagonists

Question 41

What are Renshaw cells?

Answer 41

interneurons that produce recurrent inhibition

Question 42

How are Renshaw cells stimulated?

Answer 42

by a recurrent collateral branch from the alpha motor neuron