Peripheral Nervous System - Sachen Flashcards
3 layers of peripheral nerve connective tissue
- Epineurium - whole nerve
- Supplied by vasa nervorum
- Perineurium - fascicles
- Endoneurium - fibers
A-alpha fibers
Large, proprioception and somatic motor
A-beta fibers
Large-ish, touch and pressure
A-gamma fibers
Medium, muscle spindle motor
A-delta fibers
Small-ish, pain/cold/touch
B fibers
Small-ish, pre-ganglionic autonomics
C fibers
Tiny, UNMYELINATED, pain/temp/reflexes, post-ganglionic sympathetics
2 main fiber types in peripheral neuropathies (NOT including DM)
A-alpha
C fibers
Parts of a peripheral nerve that can be affected (6)
- Cell body
- Nerve root
- Axon
- Myelin sheath
- Connective tissue
- Blood supply
Wallerian degeneration
Sever a nerve –> distal degeneration
Most common cervical nerve roots affected by a radiculopathy (w/ percentages)
Most common lumbosacral nerve roots affected (w/ percentages)
C7 = 60% C6 = 25%
L5 = 50% S1 = 45%
Causes of radiculopathy
Structural - discs, osteophytes, tumors, etc
Non-structural - DM, infections (ex. WNV), etc
Pain in shoulder
Loss of sensation in lateral arm
Weak shoulder abduction
Loss of biceps reflex
C5 radiculopathy
Pain in shoulder
Loss of sensation in lateral arm and digits 1, 2
Weak shoulder abduction and elbow flexion
Loss of biceps +/- brachioradialis reflexes
C6 radiculopathy
Shoulder/arm/forearm pain
Loss of sensation in 3rd digit
Weak UE extension muscles
Loss of triceps reflex
C7 radiculopathy
Shoulder/arm/forearm pain
Loss of sensation in digits 4, 5
Weak finger abduction and flexion
C8 radiculopathy
Pain in knee, anterior lateral thigh, medial calf
Loss of sensation in medial calf
Weak hip flexion, knee extension
L4 radiculopathy
Pain in dorsal thigh, lateral calf
Loss of sensation in lat calf, dorsal foot
Weak hamstrings, anterior leg mm
L5 radiculopathy
Pain in posterior thigh and calf
Loss of sensation in lateral calf and lateral foot
Weak hamstrings and posterior leg muscles
S1 radiculopathy
Cervical nerve roots exit (above/below) the numbered vertebra
Above (C5 root btwn C4 & C5)
Thumb/index finger
C6
Middle finger
C7
4th/5th finger
C8
Medial forearm
T1
Nipple line
T4
Umbilicus
T10
Inguinal area
L1
Medial calf
L4
Lateral calf
L5