PNS

Question 1

_____ branches of peripheral nerves supply the skin and subcutaneous tissues; ______ branches supply the muscles, tendons, and joints.

Answer 1

Cutaneous; muscular

Question 2

What do anterior rami supply? What do posterior rami supply?

Answer 2

Anterior (for plexuses) = Supply anterior/lateral trunk and extremities
Posterior = Supply skin and muscles at and around the spine

Question 3

What is the function of movement of nerves?

Answer 3

1. Helps maintain the health of nerves
2. Promotes blood flow in a nerve
3. Promotes movement of axoplasm

Question 4

What does the motor component of cutaneous branches of peripheral nerves innervate?

Answer 4

1. blood vessels
2. sweat glands
3. m’s that make hair stand up

Question 5

What does the motor component of muscular branches of peripheral nerves innervate?

Answer 5

1. skeletal muscle

2. blood vessels in muscle

Question 6

What does the sensory component of muscular branches of peripheral nerves innervate?

Answer 6

1. joint receptors
2. GTOs
3. muscle spindles
4. pain receptors in m’s
   (Kinesthesia, proprioception, pain)

Question 7

What can happen with excess lengthening of neural tissue?

Answer 7

Tensile stress develops in neural structures; Excessive stretch can damage connective structures and axons

Question 8

What happens when peripheral nerves are at rest? when they are lengthened?

Answer 8

Axons wrinkle within the endoneurium;
With lengthening of a nerve:
1.Tubes of endo-, peri- and epineurium stretch
2. Axons unwrinkled
3. Fascicles glide relative to each other

Question 9

Provides cutaneous sensory information from the posterior scalp to the clavicle.
Innervates the anterior neck muscles and diaphragm.

Answer 9

Cervical plexus:
C1-C4
Deep to SCM

Question 10

Entire upper limb is innervated by the branches.

Answer 10

Brachial plexus:
C5-T1
Between anterior and middle scalene m’s, deep to the clavicle and into the axillary region

Question 11

Branches innervate the skin and muscles of the anterior and medial thigh

Answer 11

Lumbar plexus:
L1-L4
Forms in psoas major

Question 12

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

Answer 12

Sacral plexus:

part of L4 – S4

Question 13

Dermatomes:
Face – 
Remainder of head – 
Nipple line – 
Umbilicus –

Answer 13

Face - Trigeminal (CN5)
Remainder of head – C2
Nipple line – T4
Umbilicus – T10

Question 14

Dermatomes of UE:
C4 – 
C5 – 
C6 – 
C7 – 
C8 –
T1 –

Answer 14

C4 – top of shoulder
C5 – shoulder and lateral arm
C6 – lateral forearm and first 2 digits
C7 – Middle digit
C8 – 4th and 5th digits
T1 – Medial arm and forearm

Question 15

Dermatomes of LE:
L2 – 
L3 –  
L4 – 
L5 – 
S1 – 
S2, S3, S4

Answer 15

L2 – anterolateral thigh
L3 – anteromedial thigh and knee
L4 – anteromedial shin
L5 – anterolateral shin and top of foot to big toe
S1 – small toe, lateral foot, sole and calf
S2, S3, S4 perineal region

Question 16

Where are disc herniations most common? what nerve roots are involved?

Answer 16

Cervical and lumbosacral;

Nerve root involved usually corresponds to the lower of the adjacent two vertebrae

Question 17

Even without an action potential, the presynaptic terminal continuously releases small amounts of Ach, one vesicle at a time; This produces small depolarizations in the muscle. What is the small depolarization called?

Answer 17

Miniature End Plate Potentials (MEPPS)

Question 18

What is the fiction of mEPPs? What does the loss of mEPPs indicate and produce?

Answer 18

Function - promote muscle health
If there are no mEPPs:
- Nerve is injured
- Muscle atrophy (fast and drastic, as in LMN injury)

Question 19

autoimmune disease that damages ACh receptors at the neuromuscular junction; Repeated use of a muscle leads to increasing weakness.

Answer 19

Myasthenia gravis

Question 20

causes blocks the release of ACh from the motor axon; Produces acute, progressive weakness, with loss of stretch reflexes; sensation remains intact

Answer 20

Botulism

Question 21

Disorder intrinsic to muscle;l Paresis; Often more proximal than distal weakness; NOT due to dysfunction of the nervous system

Answer 21

Myopathy

i.e., muscular dystrophy

Question 22

Disorders of peripheral nerves

Answer 22

neuropathy

Question 23

What are the sensory changes seen in neuropathies?

Answer 23

• Include decreased or lost sensation.
• Abnormal sensations include the following:
  Hyperalgesia
  Dysesthesia
  Paresthesia
  Allodynia

Question 24

What are the autonomic changes seen in neuropathies?

Answer 24

Single nerve: Signs are usually observed only if the nerve is completely severed.

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

Question 25

What are the motor changes seen in neuropathies?

Answer 25

1. paresis or paralysis
2. If the muscle is denervated, electromyogram (EMG) recordings show no activity for +/-1 weeks after the injury.
3. Muscle atrophy progresses rapidly
4. Fibrillations

Question 26

What are the trophic changes seen in neuropathies?

Answer 26

1. Changes that occur in the denervated tissues: Skin becomes shiny, Nails become brittle, Subcutaneous tissues thicken
2. Changes in blood supply, sensation and lack of movement: Ulceration of cutaneous and subcutaneous tissues, Poor healing of wounds, Increased risk of infection, Neurogenic joint damage

Question 27

Involves a single nerve and is considered a focal dysfunction

Answer 27

Mononeuropathy

Question 28

Involves several nerves and is multifocal (i.e., asymmetrically involves individual nerves); Individual nerves are affected, producing a random, asymmetrical presentation of signs

Answer 28

Multiple mononeuropathy

Question 29

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

Answer 29

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

Question 30

What are the three categories of mononeuropaties?

Answer 30

1. Traumatic myelinopathy - Neurapraxia
2. Traumatic axonopathy - Axonotmesis
3. Severance - Neurotmesis

Question 31

Refers to the loss of myelin limited to the site of injury; interfere with the function of large-diameter axons; cause is focal compression of a peripheral nerve (can be due to repeated mechanical stimuli)

Answer 31

Traumatic myelinopathy

- recovers

Question 32

With recovery from traumatic myelinopathy, what is the difference you see in schwaan cells as they regenerate?

Answer 32

They come back much shorter

Question 33

Disrupts axons and Wallerian degeneration; occurs distal to the lesion; affect all sizes of axons; reflexes, somatosensation, and motor functions are significantly reduced or absent; regenerating axons are able to reinnervate appropriate targets because myelin and connective tissues remain intact

Answer 33

Traumatic axonopathy

- recovers

Question 34

Occurs when nerves are physically divided by excessive stretching or a laceration; Axons and connective tissue are completely interrupted; If proximal and distal nerve stumps are apposed and scarring does not interfere, some sprouts enter the distal stump and are guided to their target tissue in the periphery

Answer 34

Severance

• results in immediate loss of sensation and/or m paralysis
• poor recovery

Question 35

What may cause multiple mononueropathy?

Answer 35

vasculitis

Question 36

What are causes of polyneuropathy?

Answer 36

Cause can be toxic, metabolic, or autoimmune.

• Most common causes include diabetes, nutritional deficiencies secondary to alcoholism, and autoimmune diseases
• Variety of therapeutic drugs, industrial and agricultural toxins, and nutritional disorders can cause polyneuropathy

Question 37

The most common inherited polyneuropathy; Generally causes 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; Onset typically occurs in adolescence or in young adults but varies with the type

Answer 37

Charcot-Marie-Tooth disease

Question 38

What are the causes of diabetic polyneuropathy?

Answer 38

1. vascular changes
2. metabolic changes
   - usually distal symmetrical polyneuropathy

Question 39

What part of the nerve is injured in diabetic polyneuropathy? what functions are predominantly affected?

Answer 39

axons and myelin sheaths;

Sensory neurons: Decreased sensations, Pain, Paresthesias, Dysesthesias

Question 40

What type of exercises may enhance sensory and motor recovery? what may delay functional recovery/

Answer 40

Enhance - endurance exercise

Delay - resistance training