3.7 PNS stuff 2 Flashcards
“unmyelinated”
shares myelin with other cells
each PNS axon is myelinated and coated with
endoneurium
fascicle
bundle of axons coated with perineurium
epineurium
coats bundle of fascicles (nerve)
mesoneurium
- coats the epineurium
- connective tissue that protects the fascicles
perineurium
- continuous with arachnoid mater
- forms the blood nerve barrier
blood nerve barrier
protective mechanism to keep toxins from getting into the nerves
ramus
division/offshoot of a spinal nerve
ventral rami innervate
lateral anterior regions
dorsal rami innervate
paravertebral (midline posterior) and intercostals
in a PNS nerve bundle, there what signals are happening?
afferents AND efferents
peripheral nerves (signals)
- peripheral nerve ⟺ viscera (autonomic)
- peripheral nerve ⟺ somatic » motor
sensory » somatic
sensory » cutaneous
cutaneous » sweat glands, arterioles, sympathetic efferents
muscular
can be either muscular or can get proprioceptive input
What are the plexuses?
- cervical
- brachial
- lumbar
- sacral
cervical plexus consists of
C1-C5
» skin of neck, back of scalp
» deep neck muscles
C3-C5 »
phrenic nerve
phrenic nerve innervates
diaphragm
most important output of the cervical plexus
phrenic nerve
brachial plexus runs from
C5-T1
5 major nerves of brachial plexus
- musculocutaneous
- axillary
- median
- radial
- ulnar
musculocutaneous nerve
- bicep
- brachialis
- overlying skin
axillary nerve
- deltoid
- teres minor
- overlying skin
median nerve
- anterior forearm
- skin of lateral hand
radial nerve
- triceps and overlying skin
- back of forearm
*follows radius
ulnar nerve
- medial part of hand
- forearm
- overlying skin
lumbar plexus levels
- L1-L4
2 major nerves of lumbar plexus
- femoral nerve
- obturator nerve
femoral nerve:
- anterior leg
- quad
- overlying skin
femoral nerve branch
forms saphenous nerve (bottom part of leg)
obturator nerve
- adductors
- overlying skin
sacral plexus levels
L4-S4
major nerve of sacral plexus
sciatic nerve
sciatic nerve consists of
- tibial nerve
- peroneal nerve
tibial nerve
- posterior thigh
- posterior LE
- foot
- overlying skin
peroneal nerve
- lower anterolateral leg
- deep foot muscles
- overlying skin
5 major things that can happen with PNS lesions
- paralysis
- paresis
- loss of sensation
- muscle weakness (atrophy)
- reduced or absent reflexes
