3.14 Ch. 12.1

Question 1

peripheral nerves consist of

Answer 1

parallel bundles of axons surrounded by three connective tissue sheaths

Question 2

3 connective tissue sheaths of peripheral nerves

Answer 2

• endoneurium
• perineurium
• epineurium

Question 3

endoneurium

Answer 3

Separates individual axons.

Question 4

perineurium

Answer 4

Surrounds fascicles

Question 5

epineurium

Answer 5

Encloses the entire nerve trunk

Question 6

peripheral nerves supply

Answer 6

• visceral

- somatic structures

Question 7

somatic peripheral nerves

Answer 7

usually mixed and include sensory, autonomic, and motor axons

Question 8

cutaneous branches supply

Answer 8

• skin

- subcutaneous tissues

Question 9

muscular branches supply

Answer 9

• muscles
• tendons
• joints

Question 10

peripheral axon classification

Answer 10

• speed of conduction

- diameter

Question 11

nerve plexuses formed by

Answer 11

anterior rami

Question 12

What are the plexuses?

Answer 12

• cervical
• brachial
• lumbar
• sacral

Question 13

cervical plexus innervates

Answer 13

• anterior neck muscles

- diaphragm

Question 14

cervical plexus provides cutaneous sensory info from

Answer 14

posterior scalp to the clavicle

Question 15

brachial plexus innervates

Answer 15

entire UE

Question 16

lumbar plexus innervates

Answer 16

skin and muscles of anterior and medial thigh

Question 17

sacral plexus innervates

Answer 17

posterior thigh and most of the leg and foot

Question 18

What type of axons does the sacral plexus contain?

Answer 18

parasympathetic

Question 19

How does movement affect nerve health?

Answer 19

promotes blood flow through the nerves and flow of axoplasm through the axons

Question 20

How does movement affect the axoplasm?

Answer 20

causes it to thin and flow more easily

Question 21

Where do motor axons synapse with motor fibers?

Answer 21

at NMJ

Question 22

summation of action potentials and NMJ

Answer 22

no summation needed to depolarize the postsynaptic membrane

Question 23

depolarization of motor axon in a normal motor unit

Answer 23

every depolarization releases sufficient ACh to initiat AP in the innervated muscle fibers

Question 24

Signs of peripheral nerve damage

Answer 24

• sensory
• autonomic
• motor

**All signs are in a peripheral nerve distribution.

Question 25

sensory changes in peripheral nerves

Answer 25

decreased or lost sensation

abnormal sensations

• hyperalgesia
• dysesthesia
• paresthesia
• allodynia

Question 26

autonomic changes: signs depend on

Answer 26

pattern of axonal dysfunction

Question 27

autonomic changes: single nerve dysfunction signs

Answer 27

usually observed only if the nerve is completely severed

Question 28

autonomic changes: many nerves

problems include:

Answer 28

difficulty regulating

• BP
• HR
• sweating
• bowel/bladder functions
• impotence

Question 29

motor changes: signs of peripheral nerve damage

Answer 29

paresis

paralysis

Question 30

EMG activity for denervated muscles

Answer 30

recordings show no activity for +/- 1 week after injury

Question 31

What happens to muscle fibers with peripheral nerve damage?

Answer 31

• muscle atrophy progresses rapidly

- fibers develop a sensitivity to ACh along muscle membrane (get fibrillation)

Question 32

fibrillation and lesions

Answer 32

fibs are not diagnostic of a specific lesion

Question 33

When do trophic changes begin in denervated tissues?

Answer 33

when nerve supply is interrupted

Question 34

appearance of tissues with trophic changes

Answer 34

• muscles atrophy
• skin becomes shiny
• nails become brittle
• subcutaneous tissues thicken
• ulceration

Question 35

trophic changes and neurological/blood flow issues

Answer 35

• poor healing
• neurogenic joint damage
• blood supply changes
• loss of sensation
• lack of movement