It was Saturday night, and Devon had too many beers. He was standing on the second floor balcony, loudly boasting that he was going to do a swan dive into the swimming pool. Everybody told him not to dive because he was too drunk and the pool was too shallow. Devon wouldn't listen because he wanted to show off to the new coed. Shouting, "Look at me!" he jumped off the balcony and dove into the pool. He struck his head on the bottom and broke his neck. Although he survived the accident, Devon cannot move any part of his body or feel any sensations from his shoulders down. However, all his other sensory and motor functions are completely normal. (Be very clear, use the terms afferent and efferent when needed, and indicate direction of neural transmission.) I GIVE YOU THIS ANSWER IN THE VIDEO LECTURE ON THE NERVOUS SYSTEM!
A. Why doesn't Devon have any sensations below his shoulders? (Hint: It is always best to start your description where the sense of touch starts in your body, in the skin.)
B. Why can't Devon move his muscles below his shoulders? (Hint: it is always best to start where movement signals start, in the primary motor cortex in the frontal lobes.)