Chapter 12

Question 1

What is included in the peripheral nervous system?

Answer 1

cranial nerves

peripheral nerves

Question 2

Cranial nerves:

Answer 2

arising from the brain and brainstem

Question 3

Peripheral nerves:

Answer 3

including all neural structures (axons of sensory, motor, and autonomic neurons) distal to the spinal nerves e.g., the median and tibial nerves

Question 4

What are the three connective tissue sheaths of peripheral nerves?

Answer 4

endoneurium
perineurium
epineurium

Question 5

Endoneurium:

Answer 5

Separates individual axons

Question 6

Perineurium:

Answer 6

Surrounds bundles of axon (fascicles)

Question 7

Epineurium:

Answer 7

Encloses the entire nerve trunk.

Question 8

Function of peripheral nerves:

Answer 8

Supply both the viscera (autonomic) and somatic structures

Question 9

What kind of axons are somatic peripheral nerves?

Answer 9

sensory
autonomic
motor

Question 10

What do cutaneous branches supply?

Answer 10

the skin and subcutaneous tissues, including sensory and autonomic related information

Question 11

What do muscular branches supply?

Answer 11

the muscles, tendons, and joints

Question 12

How are peripheral axons classified?

Answer 12

according to diameter and speed of conduction

Question 13

What are some examples of peripheral nerves?

Answer 13

Ia, Ib, II, Aα, and C

Question 14

From where does the cervical plexus arise?

Answer 14

arising from ant. rami of C1-C4

Question 15

What forms the brachial plexus?

Answer 15

formed by ant. rami of C5-T1

Question 16

What forms the lumbar plexus?

Answer 16

from ant. rami of L1-L4

Question 17

What forms the sacral plexus?

Answer 17

from (part of L4) – S4

Question 18

Function of cervical plexus:

Answer 18

Provides cutaneous sensory information from the posterior scalp to the clavicle

Question 19

What does cervical plexus innervate?

Answer 19

Innervates the anterior neck muscles and diaphragm.

Question 20

What is innervated by the brachial plexus?

Answer 20

Entire upper limb is innervated by the brachial plexus branches.

Question 21

What does the lumbar plexus unnervate?

Answer 21

the skin and muscles of the anterior and medial thigh

Question 22

What does the sacral plexus innervate?

Answer 22

Innervates the posterior thigh and most of the leg and foot; contains parasympathetic axons

Question 23

What does movement of promote?

Answer 23

blood flow

flow of axoplasm through the axons

Question 24

What does blood flow throughout the nerves do?

Answer 24

supply nutrition and oxygen and to remove waste from neural tissues

Question 25

What does flow of axoplasm through the axon do?

Answer 25

facilitates transport of chemicals from the axons and surrounding structures to the cell body & vice versa

Question 26

Where do motor axons synapse with muscle fiber?

Answer 26

at neuromuscular junctions

Question 27

What are signs of peripheral nerve damage?

Answer 27

sensory autonomic motor

Question 28

What does sensory changes include?

Answer 28

decreased or lost sensation

Question 29

What is included in abnormal sensation?

Answer 29

Hyperalgesia Dysesthesia Paresthesia Allodynia

Question 30

What do autonomic changes depend on?

Answer 30

the pattern of axonal dysfunction

Question 31

Autonomic changes in a single nerve:

Answer 31

Signs are usually observed only if the nerve is completely severed

Question 32

Autonomic changes in many nerves:

Answer 32

Problems may include difficulty regulating blood pressure, heart rate, sweating, bowel and bladder functions, and impotence.

Question 33

Signs of motor changes in peripheral nerves

Answer 33

paresis or paralysis

Question 34

Mononeuropathy:

Answer 34

Involves a single nerve and is considered a focal dysfunction

Question 35

Multiple mononeuropathy

Answer 35

Involves several nerves and is multifocal

Question 36

Polyneuropathy

Answer 36

Involves many nerves and is a generalized disorder that typically has a distal and symmetrical presentation.

Question 37

Classification of traumatic injuries to peripheral nerves:

Answer 37

Traumatic myelinopathy Traumatic axonopathy Traumatic severance

Question 38

What is traumatic myelinopathy?

Answer 38

loss of myelin limited to the site of injury.

Question 39

What is affected by myelinopathy?

Answer 39

function of large diameter axons

Question 40

What causes traumatic myelinopathy?

Answer 40

focal compression

Question 41

What does traumatic axonopathy disrupt?

Answer 41

Wallerian degeneration; occurs distal to the lesion.

Question 42

What does axonopathies affect?

Answer 42

all sizes of axons; reflexes, somatosensation, and motor functions are significantly reduced or absent

Question 43

Why are regenerating axons able to reinnervate appropriate targets?

Answer 43

because myelin and connective tissues remain intact

Question 44

When does traumatic severance occur?

Answer 44

when nerves are physically divided by excessive stretching or a laceration.

Question 45

What is affected in traumatic severance?

Answer 45

Axons and connective tissue

Question 46

What happens when axons and connective tissue are completely interrupted?

Answer 46

immediate loss of sensation and/or muscle paralysis in the area supplied.

Question 47

In traumatic severance, when does Wallerian degeneration begin?

Answer 47

distal to the lesion 3 to 5 days later. Then axons in the proximal stumps begin to sprout

Question 48

What does multiple mononeuropathy involve?

Answer 48

Involves two or more nerves in different parts of the body | -asymmetrical presentation

Question 49

When does multiple mononeuropathy occur?

Answer 49

when diabetes or vasculitis (inflammation of blood vessels) cause ischemia of the nerves

Question 50

What are the hallmark signs of polyneuropathy?

Answer 50

symmetrical involve-ment of sensory, motor, and autonomic fibers, often progressing from distal to proximal

Question 51

Where doe symptoms typically being in polyneuropathy?

Answer 51

begin in the feet and then appear in the hands and areas of the body supplied by the longest axons

Question 52

What are the causes of polyneuropathy?

Answer 52

not trauma or ischemia; can be toxic, metabolic or autoimmune common causes: diabetes, nutritional deficiencies secondary to alcoholism and autoimmune diseases

Question 53

What is Charcot-Marie-Tooth diease?

Answer 53

common inherited for of polyneuropathy

Question 54

What does Charcot-Marie-Tooth diease cause?

Answer 54

paresis of muscles distal to the knee with resulting foot drop, step-page gait, frequent tripping, and muscle atrophy ;in progression, muscle atrophy and paresis affect the hands.

Question 55

What does therapy for Charcot-Marie-Tooth diease involve?

Answer 55

strengthening, stretching, conditioning, muscle, joint and skin protection

Question 56

Myasthenia gravis:

Answer 56

an autoimmune disease that damages ACh receptors at the neuromuscular junction

Question 57

What is myopathy?

Answer 57

intrinsic to muscles

Question 58

What is intact in myopathy?

Answer 58

Sensation and autonomic function remain intact because the nervous system is not affected by myopathy.

Question 59

What can nerve conduction study (NCS) differentiate between?

Answer 59

processes between primarily demyelinating (myelinopathy) and damaging axon (axonopathy) UMN and LMN paresis mononeuropathy and polyneuropathy Local conduction block and Wallerian degeneration

Question 60

What signs correlate highly with electrodiagnostic evidence of peripheral neuropathy?

Answer 60

Absence of ankle jerk reflex despite facilitation Impaired vibration Impaired position sense of the great toe