PNS

Question 1

Connective tissue coverings in PNS

Answer 1

epineurim - tough fibrous sheath
perineurium - bundles fibers into fascicles
endoneurium - encloses each individual axon

Question 2

Anatomical classification of peripheral nerves

Answer 2

cranial nerves - arise from brain

spinal nerves - arise from spinal cord

Question 3

Functional classification of peripheral nerves

Answer 3

mixed nerves - both sensory (afferent) and motor (efferent) fibers
somatic & autonomic

Question 4

Ganglia

Answer 4

neuronal cell bodies:

1. dorsal root ganglia - sensory, somatic, sensations to spinal cord.
2. autonomic ganglia - motor, visceral, sympathetic & parasympathetic

Question 5

Spinal Nerves

Answer 5

31 pairs : 
8 cervical 
12 thoracic 
5 lumbar
5 sacral 
1 coccygeal

Question 6

Spinal nerve roots

Answer 6

ventral roots - only motor fibers (efferent fibers from ventral horn motor neurons)
dorsal roots - only sensory fibers (afferent fibers from dorsal root ganglia)

Question 7

Spinal nerve rami

Answer 7

nerve branches:

1. dorsal ramus - supplies posterior body trunk (mixed) - back
2. Ventral ramus - supplies rest of trunk and limbs (front)

Question 8

clinical importance of dorsal ramus

Answer 8

1. viruses that lie dormant in nerve ganglia (chickenpox, herpes) cause rash and/or pain; affect a pattern defined by a dermatome
2. spinal cord injury - dermatomes affected indicate which nerve has been injured

Question 9

dermatome

Answer 9

skin segment
area of skin innerved by single spinal nerve
dorsal ramus
most overlap - destruction of a single nerve will not cause complete numbness
hilton’s law - nerve innervating a muscle also innervates the joint and skin over joint

Question 10

Ventral ramus

Answer 10

most branch and join to form plexuses 
1. cervical 
2. brachial 
3. lumbar
4. sacral 
thoracic nerves T2-T12 give rise to intercostal nerves

Question 11

cervical plexus

Answer 11

ventral rami of C1-C4
Phrenic nerve
Neck, ear, back of head, shoulders, diaphragm*phrenic

Question 12

Brachial plexus

Answer 12

Ventral rami of C5-T1
Axillary, Musculocutaneous, Median, Ulnar, Radial
upper limb & superior thorax, Shoulder (axillary), arm (musculocutaneous), forearm & hand (ulna, medial, radial)

Question 13

Lumbar plexus

Answer 13

Ventral rami of L1-L4
Femoral nerve (quad), obturator nerve
nerve, abdominal wall & psoas muscle

Question 14

Sacral Plexus

Answer 14

ventral rami of L4-L5, S1-S4
Sciatic nerve (longest & thickest nerve of body), composed of two nerves - tibial and common fibular
buttock, lower limb, pelvic structures and perineum
sciatic nerve - innervates most muscles and skin of lower limb

Question 15

EEG

Answer 15

Electrodes pick up variations in electric potential from coritcal activity
affected by state of arousal of cerebral cortex
Algebraic sum of electrical potential changes occurring from populations of cells

Question 16

rhytmic events in waves arise from

Answer 16

thalamus

activity in thalamus affected by variety of inputs including reticular formation

Question 17

Alpha Waves

Answer 17

8-13 Hz; avg amplitudes 30-50 microV
eyes closed & volunteer relaxed
greater activity, lower alpha activity
strongest over occipital & frontal cortex

Question 18

Beta Waves

Answer 18

13-30 Hz; <20 microV

awake, alert

Question 19

Theta waves

Answer 19

4-8 Hz; <30 microV
normal during sleep, only found in awake children
low theta - decreased arousal and increased drowsiness
high theta - enhanced during memory involved tasks

Question 20

Delta waves

Answer 20

0.5-4 Hz; 100-200 microV
dominant in sleep stages 3 & 4
highest amplitude
EEG artifacts caused by movements of jaw and neck muscles can produce waves in same band

Question 21

Gamma waves

Answer 21

30-50 Hz
existence and importance controversial
higher mental activity - perception and consciousness, disappears under anesthesia
may be involved in integrating aspects to form a picture
enhanced in buddhist monks during meditation & absent schizophrenics