Matt is sitting in a chair at a table anxiously waiting for his pizza to arrive. The doorbell rings and Matt moves from his chair to go to the door to meet the pizza delivery guy. In the process of moving from his chair to ultimately sitting back in his chair and eating his pizza he has to progress through a series of motions. First he must stand upright from his sitting position in the chair. He turns around 180 degrees to face the door. Then he takes several steps forward, grabs the door knob, turns it 180 degrees clockwise and pulls open the door. Once he has the pizza in hand, he turns back around, walks back to his chair and sits down. He places a piece of pizza on plates for both he and Maria. He grasps his slice of pizza, raises it to his mouth, takes a bite, which he then chews and swallows.
All the actions that Matt made to move from the chair to the door and back to the table involved the contraction of voluntary skeletal muscles that are each innervated by a specific nerve and each of which cross a specific joint or set of joints to produce a specific action. The series of above actions took Matt less than 3 minutes to complete.
A. Describe in order and in detail the following movements.
Stand up from a sitting position
While standing upright, turn around 180 degrees to face opposite direction
Take several steps forward.
Reach forward and grasp a door knob
Turn a door knob 180 degrees clockwise
Sit down in a chair
Raise a grasped piece of pizza from a plate to mouth
Bite, chew and then swallow a portion of the pizza
Break down each of the above actions into an ordered series of joint movements. Actually do the actions yourself and note which joints move in what order. What muscles produces these movements and what specific nerve innervates that muscle or groups of muscle?
B. Which cranial nerve is concern with the maintenance of balance?
C. On the way to the doorknob, Matt stepped on a sharp nail. What type of reflex will he trigger? Trace the pathway from stepping on the nail to withdrawing his foot from the stimulus.