EPHE 380 – Motor Control
Scenario: Walking down a 45 degree slope with a surfboard under my left arm and a large mountaineering backpack on my back. I was walking down the trail to Sombrio Beach which is about a 1.5k hike down a steep trail to the ocean. I had a surfboard under my right arm, an axe in my left hand, and a large 40 litre hiking backpack fully loaded with supplies on my back. About half way down there is a left turn in the trail which has a declining gradient of approximately 30 degrees. Since water runs down the trail there is a grove etched out in the middle where fist sized rocks are littered and tree roots are exposed. I was fairly fatigued and not paying attention when I took the left turn and caught my right foot on an outlying root sending me stumbling down the hill. I discarded my surfboard and axe and struggled to keep my balance amidst the rocky terrain. Since I had forward momentum from tripping down the hill, when I discarded my surfboard it flew forward onto the path ahead of me about 6 feet down the trail. I stumbled a few times and then had to react quickly to jump over the surf board which lay perpendicular to my forward progress. After jumping over the surfboard I was able to regain control of my body and slow myself down to a stop and go collect my belongings. What underlying control mechanisms did my central and peripheral nervous system have to utilize in order to maintain my balance and forward progress, in a situation where I was physically fatigued and off balance on treacherously rocky and muddy downhill terrain? Answer:
The first five minutes of the walk were going smoothly with my vestibular system coordinating information about the gradient of decline to the MOTOR AREAS in my brain which was sending this information to my muscles. My muscle spindles were actively regulating my step distance through stretch receptors in my hips, sending signals via Ia afferents regarding the velocity...
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