Muscle twitch response and recruitment, summation and tetanus
Exercise 1: The effects of nerve stimulation
1. To explore the motor and sensory effects of electrical stimuli on a student volunteer, using the nerves of the forearm.
2. To examine the position where a largest muscular twich response with the lowest pulse current can be generated. This position is kept constant to determine results in exercises 2 and 3.
Refer to Human Biology Practical Manual
The position giving the largest muscular twitch response with the lowest pulse current can be generated.
A. Describe briefly what you have done for this section. (maximum 100 words)
Powerlab unit is used as a stimulator. Instead of recording, muscular responses are observed by watching hand of volunteer. Stimulus Isolator command is chosen and the settings are set in effect. The stimulator is switched off to disconnect the Isolated Stimulator terminals. The Start button in the Chart View is then clicked. The bar stimulus electrode is placed correctly over the volunteer’s ulnar nerve at the wrist. The Stimulator is switched on. Twitch contractions affecting thumb and fingers are observed. Small adjustments to placing of electrodes are done and position giving the largest twitches is kept constant throughout the experiment.
B. What are the observations that you have made? (maximum 150 words)
The bar stimulus electrode is applied with adequate amount of cream before the chart view started. The bar stimulus electrode was placed over the ulnar nerve at the wrist of the volunteer. The chart had been set up to monitor and the stimulator was activated. The bar stimulus electrode was moved over different positions at the wrist of the volunteer. The thumb of the volunteer twitch at different strength. The twitch of the thumb of...