1. Because the pectoralis major flexes the shoulder, adducts and medially rotates the humerus, depresses the pectoral girdle, and elevates the ribs, its absence would make such actions as climbing, pushing, and throwing difficult. Some synergists that could partially take over these functions include the latissimus dorsi, teres major and minor, coracobrachialis, subscapularis, and anterior portion of the deltoid. (The information to answer this is in tables 11.10 and 11.11. In table 11.11, each column that lists the pectoralis major also lists other muscles that perform the same or similar actions.)

2. If the left sternocleidomastoid were removed, for example, it would make it more difficult to bow the head and especially to look down toward the right foot.

3. Tick paralysis presents a threat of suffocation if it affects the thoracic respiratory muscles. (Entire herds of livestock are occasionally killed by tick-caused respiratory arrest.)

4. The triceps surae (gastrocnemius and soleus muscles) and calcaneal tendon are affected because they are more stretched when a person walks flat-footed than they are in a person wearing high heels.

5. The quadriceps femoris is the prime mover of knee extension and the gluteus maximus is the prime mover of hip extension; both are used in straightening the legs.

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