Matt is sitting in a chair at a table anxiously waiting for his Chinese takeout to arrive. The doorbell rings and Matt moves from his chair to go to the door to meet the delivery person. In the process of moving from his chair to ultimately sitting back in his chair and eating his sweet and sour chicken with rice, 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 jumps over his couch, takes several steps forward, grabs the door knob, turns it 180 degrees clockwise and pulls open the door. Once he has the food in hand, he turns back around, walks back to his chair and sits down. He divides the food into two bowls for both Maria and himself. He grasps the chicken and rice with a set of chopsticks, 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 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.

Describe in order and in detail the following movements.

  1. Stand up from a sitting position
  2. While standing upright, turn around 180 degrees to face opposite direction
  3. Jumping over the couch and taking several steps forward.
  4. Reach forward and grasp a door knob.
  5. Turn a door knob 180 degrees clockwise
  6. Sit down in a chair.
  7. Grasp the chopsticks.
  8. Raise the chicken and rice from a bowl to mouth.
  9. Bite, chew and then swallow a portion of the food.

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?

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