Quiz on Anatomy and Physiology

Martini: Fundamentals of Anatomy & Physiology 9th Edition
Chapter 13

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1)

The spinal cord is part of the

A)

peripheral nervous system.

B)

somatic nervous system.

C)

central nervous system.

D)

autonomic nervous system.

E)

afferent nervous system.

Answer:

C

2)

The ________ is a strand of fibrous tissue that provides longitudinal support as a component of the coccygeal ligament.

A)

conus medullaris

B)

filum terminale

C)

cauda equina

D)

dorsal root

E)

ventral root

Answer:

B

3)

Spinal nerves are

A)

purely sensory.

B)

purely motor.

C)

both sensory and motor.

D)

interneuronal.

E)

involuntary.

Answer:

C

4)

The spinal cord consists of five regions and ________ segments.

A)

5

B)

12

C)

25

D)

31

E)

The number varies widely among individuals.

Answer:

D

5)

The dorsal root ganglia mainly contain

A)

axons of motor neurons.

B)

axons of sensory neurons.

C)

cell bodies of motor neurons.

D)

cell bodies of sensory neurons.

E)

synapses.

Answer:

D

6)

The dorsal root of a spinal nerve contains

A)

axons of motor neurons.

B)

axons of sensory neurons.

C)

cell bodies of motor neurons.

D)

cell bodies of sensory neurons.

E)

interneurons.

Answer:

B

7)

The ventral root of a spinal nerve contains

A)

axons of motor neurons.

B)

axons of sensory neurons.

C)

cell bodies of motor neurons.

D)

cell bodies of sensory neurons.

E)

interneurons.

Answer:

A

8)

The tough, fibrous, outermost covering of the spinal cord is the

A)

arachnoid.

B)

pia mater.

C)

dura mater.

D)

epidural block.

E)

periosteum.

Answer:

C

9)

After age ________ the vertebral column continues to elongate, but the spinal cord itself does not.

A)

8

B)

12

C)

18

D)

4

E)

1

Answer:

D

10)

If the dorsal root of a spinal nerve is severed,

A)

output to skeletal muscles would be blocked.

B)

output to visceral organs would be blocked.

C)

the spinal cord would not be able to process information at that level.

D)

the brain would not be able to communicate with that level of the spinal cord.

E)

sensory input would be blocked.

Answer:

E

11)

The subdural space lies between

A)

the arachnoid mater and the pia mater.

B)

the pia mater and the dura mater.

C)

the dura mater and the arachnoid mater.

D)

the pia mater and the subarachnoid space.

E)

the endosteum and the periosteum.

Answer:

C

12)

The layer of the meninges in direct contact with the spinal cord is the

A)

dura mater.

B)

subarachnoid space.

C)

arachnoid.

D)

pia mater.

E)

choroid plexus.

Answer:

D

13)

A dorsal and ventral root of each spinal segment unite to form a

A)

cervical enlargement.

B)

lumbar enlargement.

C)

spinal nerve.

D)

spinal meninx.

E)

spinal ganglion.

Answer:

C

14)

In meningitis,

A)

inflammation of the meninges occurs.

B)

bacteria can be the cause.

C)

viruses can be the cause.

D)

CSF flow can be disrupted.

E)

All of the answers are correct.

Answer:

E

15)

Which of the following is true regarding an epidural block?

A)

It is commonly used as a method of pain control during labor and delivery.

B)

It affects only the spinal nerves in the immediate area of the injection.

C)

It can provide sensory and motor anesthesia, depending on the anesthetic selected.

D)

It can provide mainly sensory anesthesia, depending on the anesthetic selected.

E)

All of the answers are correct.

Answer:

E

16)

Cerebrospinal fluid flows within the

A)

filum terminale.

B)

subarachnoid space.

C)

dura mater.

D)

pia mater.

E)

arachnoid mater.

Answer:

B

17)

The spinal cord continues to elongate until about age

A)

20 years.

B)

10 years.

C)

4 years.

D)

6 months.

E)

2 months.

Answer:

C

18)

The specialized membranes that surround the spinal cord are termed the

A)

cranial meninges.

B)

cranial mater.

C)

spinal meninges.

D)

spinal mater.

E)

epidural membranes.

Answer:

C

19)

Blood vessels that supply the spinal cord run along the surface of the

A)

pia mater.

B)

dura mater.

C)

epidural space.

D)

subdural space.

E)

subarachnoid space.

Answer:

A

20)

Samples of CSF for diagnostic purposes are normally obtained by placing the tip of a needle in the

A)

dura mater.

B)

arachnoid mater.

C)

epidural space.

D)

subarachnoid space.

E)

cerebral ventricles.

Answer:

D

21)

In an adult, the conus medullaris is found at about

A)

T6.

B)

T10.

C)

L1.

D)

L5.

E)

C1.

Answer:

C

22)

Bill contracts a viral disease that destroys cells in the posterior gray horns in his spinal cord. As a result, which of the following would you expect?

A)

loss of sensation in his torso

B)

inability to breathe

C)

problems with moving his arms

D)

uncontrollable sweating of his feet

E)

problems with moving his legs

Answer:

A

23)

The white matter of the spinal cord is mainly

A)

unmyelinated axons.

B)

neuroglia.

C)

Schwann cells.

D)

myelinated and unmyelinated axons.

E)

nodes of Ranvier.

Answer:

D

24)

The gray horns of the spinal cord contain mainly

A)

nerve tracts.

B)

columns.

C)

meninges.

D)

nerve cell bodies.

E)

funiculi.

Answer:

D

25)

The posterior horns of the spinal cord contain mainly

A)

sensory nuclei.

B)

somatic motor nuclei.

C)

autonomic motor nuclei.

D)

nerve tracts.

E)

sympathetic nuclei.

Answer:

A

26)

The anterior horns of the spinal cord contain mainly

A)

sensory nuclei.

B)

somatic motor nuclei.

C)

autonomic motor nuclei.

D)

nerve tracts.

E)

sympathetic nuclei.

Answer:

B

27)

Nerve tracts or fasciculi make up the

A)

central canal.

B)

posterior gray horns.

C)

gray commissures.

D)

white columns.

E)

anterior gray horns.

Answer:

D

28)

In the spinal cord, white matter is separated into ascending and descending tracts organized as

A)

nuclei.

B)

ganglia.

C)

columns.

D)

nerves.

E)

horns.

Answer:

C

29)

The outward projections from the central gray matter of the spinal cord are called

A)

wings.

B)

horns.

C)

pyramids.

D)

fibers.

E)

tracts.

Answer:

B

30)

Axons crossing from one side of the spinal cord to the other within the gray matter are found in the

A)

anterior gray horns.

B)

lateral gray horns.

C)

posterior gray horns.

D)

gray commissures.

E)

white commissures.

Answer:

D

31)

The white matter of the spinal cord contains

A)

bundles of axons with common origins, destinations, and functions.

B)

bundles of dendrites with common origins, destinations, and functions.

C)

sensory and motor nuclei.

D)

both axons and dendrites.

E)

interneurons.

Answer:

A

Figure 13-1 The Spinal Cord
Use Figure 13-1 to answer the following questions:

32)

Identify the structure labeled "1."

A)

anterior white column

B)

lateral white column

C)

lateral white horn

D)

median commissure

E)

posterior white column

Answer:

E

33)

Identify the structure labeled "4."

A)

posterior gray column

B)

dorsal gray ganglion

C)

posterior white column

D)

posterior gray horn

E)

anterior gray horn

Answer:

D

34)

Identify the structure labeled "10."

A)

anterior white commissure

B)

anterior median fissure

C)

anterior white column

D)

anterior gray commissure

E)

anterior white horn

Answer:

D

35)

What is the function of the structure labeled "12"?

A)

control of skeletal muscle

B)

somatic sensory receiving

C)

visceral sensory receiving

D)

control of visceral effectors

E)

ascending pathway

Answer:

B

36)

What is the function of the structure labeled "14"?

A)

control of skeletal muscle

B)

somatic sensory processing

C)

control of visceral effectors

D)

somatic motor control

E)

visceral sensory processing

Answer:

C

37)

Where do somatic motor neurons reside?

A)

10

B)

12

C)

13

D)

14

E)

15

Answer:

E

38)

Where are the white columns of the spinal cord?

A)

4, 5, 6

B)

1, 2, 3

C)

7, 11

D)

12, 13

E)

8

Answer:

B

39)

The outermost connective-tissue covering of nerves is the

A)

endoneurium.

B)

endomysium.

C)

perineurium.

D)

epineurium.

E)

epimysium.

Answer:

D

40)

The preganglionic fibers that connect a spinal nerve with an autonomic ganglion in the thoracic and lumbar region of the spinal cord and carries visceral motor fibers that are myelinated form the

A)

white rami communicantes.

B)

gray rami communicantes.

C)

dorsal ramus.

D)

ventral ramus.

E)

dermatomes.

Answer:

A

41)

The postganglionic fibers that connect an autonomic ganglion in the thoracic or lumbar region with the spinal nerve and contain postganglionic fibers that innervate glands in the body wall or limbs are

A)

white rami communicantes.

B)

gray rami communicantes.

C)

dorsal ramus.

D)

ventral ramus.

E)

dermatomes.

Answer:

B

42)

Postganglionic fibers of the autonomic nervous system that innervate internal organs do not rejoin the spinal nerve but form

A)

dorsal rami.

B)

ventral rami.

C)

white rami.

D)

gray rami.

E)

sympathetic nerves.

Answer:

E

43)

Which of the following associations is incorrect?

A)

8 cervical spinal nerves

B)

11 thoracic spinal nerves

C)

5 lumbar spinal nerves

D)

5 sacral spinal nerves

E)

1 coccygeal spinal nerve

Answer:

B

44)

The ________ of each spinal nerve innervates the skin and muscles of the back.

A)

white ramus communicantes

B)

gray ramus communicantes

C)

dorsal ramus

D)

ventral ramus

E)

dermatome

Answer:

C

45)

Muscles of the neck and shoulder are innervated by spinal nerves from the ________ region.

A)

cervical

B)

thoracic

C)

lumbar

D)

sacral

E)

coccygeal

Answer:

A

46)

The ventral rami of spinal nerves C5 to T1 contribute fibers to the ________ plexus.

A)

cervical

B)

brachial

C)

lumbar

D)

sacral

E)

thoracic

Answer:

B

47)

In which plexus does the ulnar nerve arise?

A)

cranial

B)

cervical

C)

brachial

D)

lumbar

E)

sacral

Answer:

C

48)

In the condition ________, a virus infects dorsal root ganglia, causing a painful rash whose distribution corresponds to that of the affected sensory nerves as seen in their dermatomes.

A)

myasthenia gravis

B)

neuronal damage

C)

shingles

D)

chickenpox

E)

Hodgkin's disease

Answer:

C

49)

The layer of connective tissue that surrounds a fascicle within a peripheral nerve is the

A)

perineurium.

B)

epineurium.

C)

endoneurium.

D)

epimysium.

E)

endosteum.

Answer:

A

50)

Spinal nerves from the sacral region of the cord innervate the ________ muscles.

A)

shoulder

B)

intercostal

C)

abdominal

D)

leg

E)

facial

Answer:

D

51)

The ________ innervates the ventrolateral body surface, structures in the body wall, and the limbs.

A)

white rami communicantes

B)

gray rami communicantes

C)

dorsal ramus

D)

ventral ramus

E)

dermatomes

Answer:

D

52)

The obturator nerve is distributed to the

A)

adductors of the hip.

B)

skin over the perineum.

C)

extensors of the hip.

D)

skin over buttocks.

E)

biceps femoris.

Answer:

A

53)

A viral disease that destroys the cells of the anterior gray horn will

A)

lead to skeletal muscle weakness or paralysis.

B)

interfere with position sense.

C)

mainly interfere with crude touch and temperature sense.

D)

block autonomic regulation.

E)

affect visceral motor function.

Answer:

A

54)

The complex, interwoven network formed by contributions from the ventral rami of neighboring spinal nerves is termed a(n)

A)

dermatome.

B)

autonomic nerve.

C)

lateral nerve.

D)

tract.

E)

plexus.

Answer:

E

55)

Each of the following nerves originates in the lumbar plexus, except the ________ nerve.

A)

saphenous

B)

sciatic

C)

femoral

D)

obturator

E)

genitofemoral

Answer:

B

56)

The ________ nerve, which arises in the cervical plexus, innervates the diaphragm.

A)

ansa cervicalis

B)

lesser occipital

C)

radial

D)

phrenic

E)

sciatic

Answer:

D

57)

The layer of connective tissue that surrounds individual axons within a peripheral nerve is termed the

A)

endoneurium.

B)

perineurium.

C)

aponeurium.

D)

metaneurium.

E)

subneurium.

Answer:

A

58)

The ventral rami form four major plexuses, including all of the following, except the ________ plexus.

A)

brachial

B)

lumbar

C)

sacral

D)

nuchal

E)

cervical

Answer:

D

59)

If a person has a crush injury to the C3-C5 spinal segments, you would expect that he

A)

might be unable to breathe on his own.

B)

could walk without difficulty.

C)

would have full range of motion in all extremities.

D)

would be in a coma.

E)

would have difficulty chewing and moving the tongue.

Answer:

A

60)

As the ________ nerve approaches the knee, it divides into two branches, the fibular nerve and the tibial nerve.

A)

perineal

B)

femoral

C)

brachial

D)

pudendal

E)

sciatic

Answer:

E

61)

Mary is in an automobile accident and suffers a spinal cord injury. She has lost feeling in her lower body. Her doctor tells her that swelling is compressing a portion of her spinal cord. Which part of her cord is likely to be compressed?

A)

the anterior gray horns

B)

the anterior gray commissures

C)

ascending tracts

D)

descending tracts

E)

the anterior white commissures

Answer:

C

62)

The brachial plexus gives rise to all of the following nerves, except the

A)

radial.

B)

median.

C)

ulnar.

D)

musculocutaneous.

E)

phrenic.

Answer:

E

Figure 13-2 Spinal Nerves
Use Figure 13-2 to answer the following questions:

63)

Identify the structure labeled "2."

A)

ventral root

B)

dorsal ramus

C)

spinal nerve

D)

ventral ramus

E)

white ramus

Answer:

D

64)

Identify the structure labeled "3."

A)

spinal nerve

B)

gray ramus

C)

white ramus

D)

dorsal ramus

E)

ventral ramus

Answer:

B

65)

Identify the neuron inside the structure labeled "3."

A)

preganglionic neuron

B)

postganglionic neuron

C)

somatic motor neuron

D)

sensory neuron

E)

interneuron

Answer:

B

66)

Identify the structure labeled "4."

A)

spinal nerve

B)

gray ramus

C)

white ramus

D)

dorsal ramus

E)

ventral ramus

Answer:

C

67)

Identify the structure labeled "5."

A)

autonomic nerve

B)

autonomic ganglion

C)

rami communicantes

D)

dorsal root ganglion

E)

ventral root

Answer:

C

68)

Identify the structure labeled "6."

A)

autonomic nerve

B)

sympathetic ganglion

C)

dorsal root ganglion

D)

rami communicantes

E)

ventral root

Answer:

B

69)

Identify the structure labeled "8."

A)

peripheral nerve

B)

dorsal ramus

C)

spinal nerve

D)

ventral root

E)

dorsal root

Answer:

C

70)

What is the function of the structure labeled "12"?

A)

somatic motor control

B)

visceral motor control

C)

somatic sensory input

D)

visceral sensory input

E)

sensory receptor for pain

Answer:

B

71)

What is the function of the structure labeled "13"?

A)

sensory receptor for pain

B)

visceral sensory input

C)

somatic motor control

D)

somatic sensory input

E)

visceral motor control

Answer:

C

72)

Which branch carries motor neurons to structures on the back of the body trunk?

A)

1

B)

2

C)

5

D)

7

E)

11

Answer:

A

73)

In which structure are sensory cell bodies located?

A)

4

B)

6

C)

5

D)

10

E)

12

Answer:

D

74)

Recognized neuronal circuit patterns include all of the following, except

A)

convergent.

B)

divergent.

C)

multipolar.

D)

reverberating.

E)

parallel processing.

Answer:

C

75)

All of the following are true of neural reflexes, except that they

A)

are automatic motor responses.

B)

are the simplest form of behavior.

C)

help preserve homeostasis.

D)

cannot be modified by the brain.

E)

involve at least two neurons.

Answer:

D

76)

Reflexes based on synapses formed during development are ________ reflexes.

A)

visceral

B)

innate

C)

acquired

D)

somatic

E)

vegetative

Answer:

B

77)

Reflexes can be classified according to all of the following, except

A)

their development.

B)

where information processing occurs.

C)

the motor response.

D)

the complexity of the neural circuit.

E)

whether they are sensory or motor.

Answer:

E

78)

All of the following are true of muscle spindles, except that they

A)

are found within skeletal muscle.

B)

consist of specialized fibers called intrafusal fibers.

C)

are found in tendons.

D)

are the receptor for the stretch reflex.

E)

are innervated by gamma motor neurons.

Answer:

C

79)

The reflex that prevents a muscle from exerting too much tension is the ________ reflex.

A)

stretch

B)

tendon

C)

flexor

D)

crossed extensor

E)

reciprocal

Answer:

B

80)

Spinal interneurons inhibit antagonist motor neurons in a process called

A)

a crossed extensor reflex.

B)

a stretch reflex.

C)

a tendon reflex.

D)

reciprocal inhibition.

E)

reverberating circuits.

Answer:

D

81)

The ________ reflex complements the flexor reflex by activating contralateral muscles.

A)

stretch

B)

tendon

C)

flexor

D)

crossed extensor

E)

reciprocal

Answer:

D

82)

The flexor reflex

A)

prevents a muscle from overstretching.

B)

prevents a muscle from generating damaging tension.

C)

moves a limb away from a painful stimulus.

D)

usually depends on cranial neurons.

E)

is an example of a monosynaptic reflex.

Answer:

C

83)

In which of the following would the delay between stimulus and response be greater?

A)

a monosynaptic reflex

B)

a polysynaptic reflex

Answer:

B

84)

All of the following are true of polysynaptic reflexes, except that they

A)

are arranged according to dermatomes.

B)

are intersegmental in distribution.

C)

involve reciprocal innervation.

D)

have reverberating circuits that prolong the reflexive motor response.

E)

involve pools of interneurons.

Answer:

A

85)

Tina falls while climbing a tree and lands on her back. Her frightened parents take her to the emergency room, where she is examined. Her knee-jerk reflex is normal and she exhibits a plantar reflex (negative Babinski reflex). These results suggest that

A)

Tina has injured one of her descending nerve tracts.

B)

Tina has injured one of her ascending nerve tracts.

C)

Tina has a spinal injury in the lumbar region.

D)

Tina has a spinal injury in the cervical region.

E)

Tina suffered no damage to her spinal cord.

Answer:

E

86)

Which of the following is not true about a positive Babinski reflex?

A)

normal in newborns

B)

abnormal in adults

C)

a sign of injury to descending spinal tracts

D)

why you close your eyes when you sneeze

E)

flaring of the toes when the sole is stroked

Answer:

D

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

87)

The dura mater tapers inferiorly to form the ________.

Answer:

coccygeal ligament

88)

The condition in which a person loses all feeling and movement of the arms and legs due to spinal cord injury is termed ________.

Answer:

quadriplegia

89)

The loss of feeling and movement of the legs is termed ________.

Answer:

paraplegia

90)

The ________ separates the dura mater from the walls of the vertebral canal.

Answer:

epidural space

91)

The dorsal root contains ________ neurons.

Answer:

sensory

92)

Blood vessels traveling within the ________ space deliver oxygen and nutrients to the spinal cord.

Answer:

subarachnoid

93)

During the procedure known as a(n) ________, a needle is inserted into the subarachnoid space in the inferior lumbar region.

Answer:

lumbar puncture (or spinal tap)

94)

The white ramus and the gray ramus collectively are called the ________.

Answer:

rami communicantes

95)

Suppose that you feel something brushing against your abdomen. The sensory information would be carried to the spinal cord over a ________ ramus.

Answer:

ventral

96)

The specific strip of skin that is innervated by a specific spinal nerve is called a(n) ________.

Answer:

dermatome

97)

A complex, interwoven network of nerves is called a(n) ________.

Answer:

plexus

98)

The nerve crucial for breathing that originates within the cervical plexus is called the ________ nerve.

Answer:

phrenic

99)

In ________, one neuron synapses on several postsynaptic neurons.

Answer:

divergence

100)

In ________, axon collaterals extend back toward the source of the impulse and further stimulate the earlier neurons.

Answer:

reverberation

101)

The neural "wiring" of a single reflex is called a(n) ________.

Answer:

reflex arc

102)

________ reflexes activate skeletal muscles. (Note: Be sure to capitalize the first letter of your answer).

Answer:

Somatic

103)

The most complicated spinal reflexes are called ________.

Answer:

intersegmental reflex arcs

104)

Reflexes that activate muscles on the same side of the body as the stimulus are called ________.

Answer:

ipsilateral

105)

Reflexes that activate muscles on the opposite side of the body as the stimulus are called ________.

Answer:

contralateral

106)

In a(n) ________ reflex, a sensory neuron synapses directly on a motor neuron.

Answer:

monosynaptic

107)

A(n) ________ reflex has at least one interneuron placed between the sensory and motor neurons.

Answer:

polysynaptic

ESSAY. Write your answer in the space provided or on a separate sheet of paper.

108)

What would happen if the dorsal root of a spinal nerve were completely transected?

Answer:

The dorsal roots contain axons of sensory neurons, so input from those afferents within the severed root would not be transmitted to the CNS and thus this lesion would result in a complete loss of feeling from the body region served by the afferent fibers in that dorsal root.

109)

While playing football, Ramón is tackled hard, and as he tries to get up, he finds that he has difficulty flexing and adducting his left thigh and extending his left leg. Which nerve innervating the lower limb may be damaged, and how would the damage affect sensory perception in Ramón's left leg?

Answer:

Ramón has a damaged left femoral nerve. This nerve also supplies sensory innervation to the skin on the anteromedial surface of the thigh and medial surfaces of the leg and foot, so he will also experience numbness in those regions.

110)

What is a reflex arc? What components must be present to qualify?

Answer:

A reflex arc is the wiring pattern of neurons that underlie a particular reflex. A reflex arc consists of three elements at the minimum: (1) a sensory receptor and neuron to carry afferent information to the CNS; (2) an excitatory synapse on a motor neuron; (3) the motor neuron to generate an action potential and conduct the impulse to an effector such as a skeletal muscle motor unit.

111)

Sometimes, when it is difficult to initiate a knee-jerk reflex by tapping the patellar tendon, a patient will be asked to voluntarily make a fist. Then the reflex will be easily evoked. What does this illustrate about the relation between voluntary and involuntary reflex movement?

Answer:

Descending motor tracts that excite the motor neurons that activate forearm and hand muscles also send excitatory impulses to motor neurons lower down the spinal cord. These EPSPs spatially summate with the excitatory inputs from the muscle spindles to quadriceps motor neurons, bringing the quadriceps neurons to threshold, and thus generate a brisk "knee jerk" response.

1)

C

2)

B

3)

C

4)

D

5)

D

6)

B

7)

A

8)

C

9)

D

10)

E

11)

C

12)

D

13)

C

14)

E

15)

E

16)

B

17)

C

18)

C

19)

A

20)

D

21)

C

22)

A

23)

D

24)

D

25)

A

26)

B

27)

D

28)

C

29)

B

30)

D

31)

A

32)

E

33)

D

34)

D

35)

B

36)

C

37)

E

38)

B

39)

D

40)

A

41)

B

42)

E

43)

B

44)

C

45)

A

46)

B

47)

C

48)

C

49)

A

50)

D

51)

D

52)

A

53)

A

54)

E

55)

B

56)

D

57)

A

58)

D

59)

A

60)

E

61)

C

62)

E

63)

D

64)

B

65)

B

66)

C

67)

C

68)

B

69)

C

70)

B

71)

C

72)

A

73)

D

74)

C

75)

D

76)

B

77)

E

78)

C

79)

B

80)

D

81)

D

82)

C

83)

B

84)

A

85)

E

86)

D

87)

coccygeal ligament

88)

quadriplegia

89)

paraplegia

90)

epidural space

91)

sensory

92)

subarachnoid

93)

lumbar puncture (or spinal tap)

94)

rami communicantes

95)

ventral

96)

dermatome

97)

plexus

98)

phrenic

99)

divergence

100)

reverberation

101)

reflex arc

102)

Somatic

103)

intersegmental reflex arcs

104)

ipsilateral

105)

contralateral

106)

monosynaptic

107)

polysynaptic

108)

The dorsal roots contain axons of sensory neurons, so input from those afferents within the severed root would not be transmitted to the CNS and thus this lesion would result in a complete loss of feeling from the body region served by the afferent fibers in that dorsal root.

109)

Ramón has a damaged left femoral nerve. This nerve also supplies sensory innervation to the skin on the anteromedial surface of the thigh and medial surfaces of the leg and foot, so he will also experience numbness in those regions.

110)

A reflex arc is the wiring pattern of neurons that underlie a particular reflex. A reflex arc consists of three elements at the minimum: (1) a sensory receptor and neuron to carry afferent information to the CNS; (2) an excitatory synapse on a motor neuron; (3) the motor neuron to generate an action potential and conduct the impulse to an effector such as a skeletal muscle motor unit.

111)

Descending motor tracts that excite the motor neurons that activate forearm and hand muscles also send excitatory impulses to motor neurons lower down the spinal cord. These EPSPs spatially summate with the excitatory inputs from the muscle spindles to quadriceps motor neurons, bringing the quadriceps neurons to threshold, and thus generate a brisk "knee jerk" response.