Unit 5,6

determine the avg motor nerve fiber conduction velocity under two dif temps

• EMG recording electrodes on belly of 1st dorsal interosseous and MCP joint
• Ground electrode on back of wrist
• Ulnar nerve stimulated at wrist and elbow (cathode distally)
• Distance between elbow and wrist cathodes measured (mm)

• Forearm in plastic bag, ice on top for 30 min
• Ulnar nerve stim at elbow wrist

• Cooling slows avg NCV bc the enzymes which dictate the rate of ATP regeneration slow down
• which slows the Na/K pump
• Increases time needed to generate AP
• Decreasing the avg motor nerve fiber conduction velocity

****Cooling nerve slows NCV therefore taking longer time for the AP to reach the muscle creating delay in the appearance of the M-wave

• determined the impact of changing length of lever arm on the load needed to achieve static equilibrium
• determined the impact of changing the length of the lever arm on myometer readings during MVC (iso) biceps

up

down

biceps force and lever arm A

load force and lever arm B

• Load arm
• load force to axis of rotation (elbow joint)

• effort arm
• length from biceps tendon to axis of rotation

load force placed on 3 dif positions on lever arm A to equal 90 degree angle both theta and phi

• if weight increase proportionally to the degree of shortening of lever arm A
• ---then load torques equal
• ---muscle force values equal

• 3 restraining strap positions
• 3 MVC with 5 min rest, holding forearm at 90° (angle theta)

perpendicular distance from the pt where force exerted to the axis of rotation  bc we couldn’t measure the angle btw biceps tendon and axis of forearm

• weight increase proportionally to the degree of shortening of lever arm A
• ---then myometer torques equal
• ---muscle fore values equal