Exam 1 Flashcards
What dermatome does the clavicle correlate with?
C4
What dermatomes correlate with the nipples?
T4-T5
What dermatomes correlate with the xiphoid?
T6-T8
What dermatomes correlate with the inferior border of the scapula?
T7
What dermatomes correlate with the umbilicus?
T10
What dermatomes correlate with the Superior border of the iliac crest?
L4
What dermatomes correlate with the perineum?
S2-S5
What are the 3 classes of nerves?
motor, sensory and autonomic.
What class of nerves transmit sensations such as touch and pain to the spinal cord and from there to the brain.
sensory
What class of nerves Controls the caliber of blood vessels, heart rate, gut contraction and other functions not under conscious control.
autonomic - the PNS and SNS
What class of nerves convey messages for muscles to contract and when they are blocked muscle paralysis results.
motor
What is the goal of every regional anesthetic
Sensory anesthesia (or analgesia)
What is local anesthetics Mechanism of action
Local anesthetics bind to sodium channels, in the inactivated-closed state, thus preventing them from converting to activated-open or rested-closed.
When are Sodium channels not permeable to sodium and can not propagate an action potential.
in the inactivated-closed state
LAs diffuse through What
the lipid bilayer of the cell [the uncharged portion)
What does the charged portion of LA’s do once the uncharged portion diffuses through the lipid bilayer?
the charged portion accesses the Na+ channel and prevents an action potential from forming by blocking Na+ entry into the cell (the cell remains non depolarized)
Though local anesthetics bind to sodium channels in the inactivated- closed state, they only gain access during?
the activated-open state
What is Differential Blockade
Local anesthetics act on nerves at a different (or “differential”) rate, depending on The thickness of the nerve. Thicker nerves need more LA (exception to the rule is B pre-ganglionic sympathetic fibers)
Motor fibers are (blank) than sensory fibers and therefore it is possible to get sensory anesthesia, without getting muscle paralysis.
larger
What fibers are the most susceptible to conduction blockade
Preganglionic type B (despite being larger than type C fibers.)
Myelin makes the nerve fiber more or less susceptible to conduction blockade?
more
How many nodes of Ranvier does it take to block conduction?
approx 3
As nerve size increases what happen to the nodes of Ranvier?
the nodes are more spread out and it’s harder to block them
What is Nerve Fiber TypeA Alpha”s Function
Proprioception, large motor