Ch. 12: Peripheral NS

Question 1

Peripheral Nerve

Answer 1

• distal axon projections

- After nerve leaves spinal canal

Question 2

Cervical Plexus

Answer 2

• C1-C4

- motor, sensory, sympathetic to neck and tops of shoulders

Question 3

Brachial Plexus

Answer 3

• C5-C8, T1

- Motor, sensory, sympathetic to arms

Question 4

Sacral Plexus

Answer 4

• L4-S4

- motor, sensory and parasympathetic to back and bottom of legs

Question 5

Damage to spinal nerve causes:

Answer 5

• minor weakness to 1+ muscles
• (b/c Mm are innervated by more than one spinal level)

-sensory loss in dermatomal pattern

Question 6

Damage to Peripheral Nerve Causes:

Answer 6

• paralysis to 1+ Mm
• (b/c a muscle is only supplied by one peripheral nerve)

-sensory loss in peripheral pattern

Question 7

Spinal Nerve at risk from:

Answer 7

• bulging disc

- collapse of intervetebral foramen

Question 8

Lumbar Plexus

Answer 8

• L1-L4

- motor, sensory, sympathetic to front of legs

Question 9

Principles of a plexus

Answer 9

• one peripheral nerve gets axons from many different spinal levels
• one spinal level sends axons to many different peripheral nerves

Question 10

Spinal Nerve

Answer 10

• joining of one spinal level
• all sensory, motor and autonomic
• dividing line between central and peripheral NS
• dermatomal/myotomal pattern when damaged

Question 11

Rami

Answer 11

• ventral
• dorsal
• communicating

Question 12

Axon Connective Sheaths

Answer 12

• endoneurium
• perineurium
• epineurium

Question 13

Nerves and movement

Answer 13

• nerves love blood, space and movement
• Movement increases blood flow, facilitates gliding of N, and axoplasmic transport
• nerve axons have wrinkling in endoneurium to allow movement

Question 14

If nerves can’t move:

Answer 14

the axons stick to connective tissue and shorten

Question 15

Dysfunction of peripheral Nn

Answer 15

• Sensory changes
• Motor changes
• Autonomic changes

Question 16

Autonomic changes
(peripheral nerve damage)

Answer 16

• decreased function
• decreased sympathetic function

(there is no parasympathetic in peripheral nerves)

Question 17

NMJ

Answer 17

• EPSP only

- atrophy of denervation if axons die

Question 18

Sensory Changes

damage to pheripheral nerve

Answer 18

• location depends on where it’s damaged
• depends on how much damage
• Anesthetic/Analgesic or both

Question 19

Motor damage

to peripheral nerve

Answer 19

• location depends on what’s damaged

- severity depends on how much damage

Question 20

changes following denervation

Answer 20

• fibrillations

- trophic changes (to nerve, muscle, skin)

Question 21

Traumatic Axonopathy

Answer 21

• axon and myelin degenerate, but connective tissue tube remains
• Wallerian degeneration distal
• Recovery: good

Question 22

Axon regrowth rate

Answer 22

1 inch/month

Question 23

Multiple mononeuropathy

Answer 23

-involves 2+ discrete Nn in different body parts

Question 24

Classification of peripheral neuropathies

Answer 24

• mononeuropathy
• multiple mononeuropathy
• Polyneuropathy

Question 25

Traumatic Myelinopathy

Answer 25

- temporary disruption of conduction along axon membrane - axon intact - demyelination possible - Recovery: excellent - +Tine's sign (b/c demyelinated areas upregulate mechanoreceptors)

Question 26

Severance

Answer 26

- axon/myelin degenerate and connective tissue tube is severed - wallerian degeneration distal - Recovery: fair - axons may not find connective tissue tube (can form neuroma) - may go into other tube and become nonfunctional

Question 27

Polyneuropathy

Answer 27

- decreased sensory, motor, autonomic starting distal and working to proximal - no peripheral or dermatomal pattern

Question 28

Causes of Polyneuropathy

Answer 28

- diabetes - Alcoholism (nutritional deficiencies) - autoimmune (guillain barre)

Question 29

Mononeuropathy Levels

Answer 29

- traumatic myelinopathy - traumatic axonopathy - severance