nerve elements Flashcards
_________ neurons (aka somatosensory), _________ neurons (aka motor), and __________ nerves are the components of a peripheral nerve
afferent
efferent
autonomic
PNS order of physical size
peripheral nerve > afferent and efferent fibers > fascicles (bundles of axons) > individual nerve fibers (aka axons)
functional unit is the
axon
________ cells surround the axon
schwann
_______ ______ are around the axons and between the axon and schwann cells
myelin sheaths are around the axons (in myelinated nerves) and between the axon and schwann cells
______ of _______ are interspersed among the axon at spaces that are not myelinated
nodes of ranvier
these nodes, or axon intervals, have _______ gated ______ ________ that propagate the nerve conduction and are primary site for LA action
voltage
Na channels
electrical impulses are conducted by localized depolarizations which transmit an electrical signal. resting membrane potential is negative _____ to _____ mV
-60 to -90
_________ gated _______ channels are the primary mediator for influx of ______ which propagates depolarization
voltage gated Na channels
Na
there are three states of the Na channel:
- activated open
- inactivated closed
- rested closed
LAs have the ability to block the channels in the ____ ____ _____ only
first two states only (activated open and inactivated closed)
the inability of the nerve to fire during inactivated state, the refractory period, prevents ______ _______ of the nerve impulses
retrograde conduction
nerve fibers can be _______ or __________
myelinated or unmyelinated
generally, myelinated are _____ fibers, have _______ conduction, and are associated with _______ and ______ function
larger
faster
motor and sensory function
unmyelinated fibers generally have _______ conduction and transmit ________, _______, and ________ impulses
slower
pain
temp
autonomic
nerve fiber size is classified as ___, ____, and _____, with ______ being the largest and _______ being the smallest
A, B, and C
A
C
A fibers have subgroups of _______, ________, _______, and ________ fibers, and are the most myelinated
alpha
beta
gamma
delta
alpha fibers functionality includes ______ _______ and _______-
motor signals
proprioception
beta fibers functionality includes ______, _______, and ______ recognition
motor, touch, and pressure
gamma fibers carry ______
reflexes
delta fibers transmit _______ and ________
pain and temp
B fibers have less myelination and carry _______ _______
autonomic signals
C fibers are smallest fibers and are unmyelinated, they carry ______ and _______ signals
pain and temp
with LAs, the ________ and ______ _______ the fibers are generally harder to block
larger and more myelinated
the order of blockade is generally:
B fibers, C fibers, A delta fibers followed by the heavily myelinated fibers
recovery from LA occurs in reverse order
CNS communication from the body (sensory) is through the ____________ aspect of the cord
dorsolateral
CNS communication to the body occurs through the __________ from the _________ aspect of the cord
ventral root
ventrolateral
2 roots converge to form a spinal nerve before dividing into the ______ and _______ _____ innervating the anterior and posterior structures
dorsal and ventral rami
spinal nerves are comprised of ____ pairs: ____ cervical and ____ thoracic, ____ lumbar, _____ sacral, and ____ coccygeal nerve
31 pairs
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
the vertebral bone components have multiple _________ of which the clinician should be aware
projections
_____ levels
_____ cervical, _____ thoracic, ______ lumbar _____, sacral, and _____ coccyx
33 levels
7 cervical
12 thoracic
5 lumbar
5 sacral
4 coccyx
spinous processes are directed _______ at the cervical levels while _______ at the lumbar levels
caudad
straight
C6 correlates with
cricoid cartilage
C7 is the
most prominent cervical level called “vertebral prominens”
T2 correlates with the
superior angle of the scapula and sternal notch
T4 is the
plane of ludwig that correlates carina and angle of Louis
T7 is the
inferior angle of the scapulae
T9 is the
Xiphoid
T10 correlates with the
umbilicus
L4 correlates with the
superior iliac crest
spinal nerves and their level of origin are not always exactly in line with the ______ _______ of the body where they provide coverage. the ______ _______ will show a different spinal nerve level than the vertebral height
surface landmark
dermatome chart
brachial plexus is formed by ____-_____ between the _______ and ______ _______ muscles
C5-T1
anterior and middle scalene
radial nerve forms from _____-_____. functionally operates the ______, supination of the ________, extension of the _______, abduction of the ______, and extension of ______ ______
C5-T1
triceps
forearm
wrist
thumb
other fingers
median nerve forms by _______ and _______ cords and follows the track of the brachial artery lying medially to it. functionally it flexes the _________, pronates the ________, flexes the _______, flexes the ______&______, abducts the ______
lateral and medial cords
flexes the elbow
pronates the forearm
flexes the wrist
flexes the fingers and thumb
abducts the thumb
ulnar nerve - formed by ____-____, follows the _____ ______ following the posterior aspect of the medial epicondyle. flexion of the _____, ______, and ____ _______, adduction of ________, adduction of ________, flexion of ______
C8-T1
follows the brachial artery
flexion of the wrist, ring, and small fingers
adduction of fingers
adduction of thumb
flexion of thumb
spinal nerves travel in the intercostal spaces and to the thoracic and abdominal compartments and are called _______ ________
intercostal nerves
femoral nerve develops from _____-_____
L2-L4
sciatic nerve is formed from _______ (___-___) and _____ ______ ______ (___-___)
tibial (L4-S3)
common peroneal nerves (L4-S2)
sciatic nerve functionally extends the _____, flexes the _____, plantar flexes ______, dorsiflexes ____ and all movement of the toes.
sciatic nerve functionally extends the hips, flexes the knee, plantar flexes the ankle, dorsiflexes the ankle, and all movement of toes
