Assume you have a 10-lb weight in your right hand. Explain why it is easier to flex the right elbow when your forearm is supinated than when it is pronated.

Mr. Ahmadi, an out-of-shape 45-year-old man, was advised by his physician to lose weight and to exercise on a regular basis. He followed his diet faithfully and began to jog daily. One day, while on his morning jog, he heard a snapping sound that was immediately followed by a severe pain in his right lower calf. When his leg was examined, a gap was seen between his swollen upper calf region and his heel, and he was unable to plantar flex that ankle. What do you think happened? Why was the upper part of his calf swollen?

Name two muscles in each of the following compartments or regions:

a. thenar eminence (ball of thumb)

b. posterior compartment of forearm

c. anterior compartment of forearm—deep muscle group

d. anterior muscle group in the arm

e. muscles of mastication

As Kendra's coach watched her sail over the high jump bar, he contracted his right orbicularis oculi muscle, raised his arm, and contracted his opponens pollicis. Was he pleased or displeased with her performance? How do you know?

When Mrs. O'Brien returned to her doctor for a follow-up visit after childbirth, she complained that she was incontinent (having problems controlling her urine flow) when she sneezed. The physician asked his nurse to give Mrs. O'Brien instructions on how to perform exercises to strengthen the muscles of the pelvic floor. To which muscles was he referring?

What class of lever system do the following activities describe?

a. The soleus muscle plantar flexes the foot.

b. The triceps brachii is strained while doing pushups.