Chapter 14: Spinal Cord and Spinal Nerves

Question 1

Major functions of the spinal cord and nerves

Answer 1

• structural and functional link between the brain and the rest of the body
• exhibits some functional independence from the brain

Question 2

2 types of conduction (spinal) pathways

Answer 2

1- sensory pathways
2- motor pathways

Question 3

Sensory pathways

Answer 3

ascend towards the brain through the spinal cord

Question 4

Motor pathways

Answer 4

descend from the brain through the spinal cord

Question 5

3 Characteristics of pathways

Answer 5

• most pathways intersect while traveling through the white matter of the spinal cord
• consists of paired tracts
• are composed of two or three neurons working together

Question 6

What is a dermatome?

Answer 6

a segment of skin supplied by a single spinal nerve and can help localize damage to one or more spinal nerves and is involved in visceral pain; all spinal nerves except C1

Question 7

Referred pain

Answer 7

pain from one organ referred to a dermatome

Question 8

What does it mean to be contralateral?

Answer 8

stimulus on one side and response on the other

Question 9

What does it mean to be ipsilateral?

Answer 9

stimulus and response on the same side

Question 10

2 types of sensory pathway receptors

Answer 10

1- somatosensory receptors
2-visceral sensory receptors

Question 11

2 kinds of somatosensory receptors

Answer 11

1- tactile receptors
2- proprioceptors

Question 12

Tactile receptors

Answer 12

detect characteristics of an object

Question 13

Proprioceptors

Answer 13

detect stretch in joints, muscles, tendons

Question 14

Visceral sensory receptors

Answer 14

detect changes in an organ

Question 15

Characteristics of sensory pathways

Answer 15

• somatosensory pathways: carry signals from skin, muscles, joints
• visceral sensory receptors: carry signals from viscera

Question 16

Characteristics of sensory pathways

Answer 16

• at least 2, maybe 3 sensory neurons in the path
• use a series of neurons to relay signals to brain

Question 17

Primary (1st order) neuron

Answer 17

detects stimuli with dendrite receptors within the posterior root ganglion

Question 18

Secondary neuron

Answer 18

is an interneuron located within the dorsal gray horns of the spinal cord or brainstem nucleus; integrates sensory info and directs to appropriate brain regions

Question 19

Tertiary neuron

Answer 19

an interneuron located in the thalamus; consolidates sensory info deemed “important” by the thalamus and transfers to the appropriate sensory cortex

Question 20

Characteristics of motor pathways

Answer 20

• control effectors such as skeletal muscles
• start in brain and include at least two neurons

Question 21

2 types of motor pathways neurons

Answer 21

1- upper motor neuron
2- lower motor neuron

Question 22

Upper motor neuron

Answer 22

cell body within the cerebral cortex or nuclei of the brainstem; excites or inhibits the activity of the lower motor neuron

Question 22

Lower motor neuron

Answer 22

cell bodies housed within the anterior/ventral horn of the spinal cord or nuclei of the brainstem; always excitatory; axons exit CNS; excites a muscle and cause contraction

Question 23

Main properties of a reflex

Answer 23

• a stimulus is required to initiate a reflex
• the response is rapid; it involves a chain of only a few neurons
• the response is preprogrammed; always the same
• the response is involuntary; no intent or awareness of the reflex before it happens

Question 24

Shingles

Answer 24

- reactivation of chickenpox - rash and blisters along the dermatome

Question 25

Reflexes

Answer 25

rapid, preprogrammed, involuntary responses of muscles or glands to a stimulus

Question 26

What is a reflex arc?

Answer 26

the neural "wiring" of a single reflex

Question 27

The 5 steps involved in the activation of a reflex?

Answer 27

1- a stimulus activates a receptor 2- generates a nerve signal that travels by sensory neurons to the CNS 3- information processed by interneurons of CNS (only if it is a polysynaptic reflex) 4- motor neuron sends the nerve signal to an effector 5- the effectors (muscle or gland) resond

Question 27

Reflex classifications

Answer 27

- spinal or cranial - somatic or visceral - monosynaptic or polysynaptic - ipsilateral or contralateral - innate or acquired

Question 28

Spinal or cranial

Answer 28

is the spinal cord or brain the reflex integration center?

Question 29

Somatic or visceral

Answer 29

is the effector a skeletal muscle or is it cardiac muscle, smooth muscle, a gland?

Question 30

Monosynaptic or polysynaptic

Answer 30

do sensory neurons synapse directly with motor neurons or are they interneurons in the reflex arc?

Question 31

Ipsilateral or contralateral

Answer 31

are receptor and effector on the same side of the body or on opposite sides?

Question 32

Innate or acquired

Answer 32

are you born with the reflex or do you develop it after birth?

Question 33

What is a monosynaptic reflex?

Answer 33

simplest reflex with no interneuron

Question 34

What is a polysynaptic reflex?

Answer 34

more complex and always involves at least 1 interneuron

Question 35

4 common spinal reflexes

Answer 35

1- stretch reflex 2- golgi tendon reflex 3- withdrawal reflex 4- crossed-extensor reflex

Question 36

Stretch reflex

Answer 36

reflexive contraction of a muscle after it is stretched; stretch is detected by a muscle spindle proprioceptor

Question 37

Tendon reflex

Answer 37

prevents muscles from contracting excessively

Question 38

Withdrawal reflex

Answer 38

pulls a body part away from a painful stimulus

Question 39

Crossed-extensor reflex

Answer 39

occurs in conjunction with withdrawal reflex; allows the opposite side limb to support body weight while hurt limb withdrawals

Question 40

Stretch reflex classified as

Answer 40

- spinal - somatic - monosynaptic - ipsilateral - innate

Question 41

Golgi tendon reflex classified as

Answer 41

- spinal - somatic - polysynaptic - ipsilateral - innate

Question 42

Withdrawal reflex classified as

Answer 42

- spinal - somatic - polysynaptic - ipsilateral - innate

Question 43

Crossed-extensor reflex classified as

Answer 43

- spinal - somatic - polysynaptic - contralateral - innate

Question 44

Hypoactive reflex

Answer 44

diminished or absent; may indicate damage to the spinal cord, muscle disease, or damage to the neuromuscular junction

Question 45

Hyperactive reflex

Answer 45

abnormally strong response; may indicate damage to the brain and spinal cord, especially if accompanied by clonus (rhythmic oscillating movements with reflex testing)

Question 46

Reciprocal inhibition

Answer 46

inhibiting antagonistic muscle contraction

Question 47

Reciprocal activation

Answer 47

stimulation of alpha motor neurons of antagonistic muscles

Question 48

Muscle spindle

Answer 48

stretch receptors that signal the length and changes in length of muscles