Mammalia. 151 



covered by a thin, glistening membrane, the muscle sheath. 

 Study the shapes of the muscles. 



2. In the hind limb of the rabbit observe the heel cord, or, 

 Achilles tendon, passing upward from the heel along the back 

 of the leg. The tendon is the termination of the calf muscle, 

 which lies on the back of the shin bone. Trace this muscle 

 toward the body, and note that it passes between two large, flat 

 muscles, one on the inner, the other on the outer, back part of 

 the thigh. Separate these two flat muscles, using mainly the 

 handle of the scalpel. Remove any fat that may be in the way. 

 Deeply embedded between these muscles is a white cord, the 

 sciatic nerve. Trace this nerve toward the body, cutting away 

 any muscles or soft tissue covering it. How far can you trace 

 it? Now follow the nerve outward. Is it of the same size 

 throughout? What are its relations to the muscles? 



3. Study carefully the calf muscle, its shape, color, covering, 

 ends, etc. The end by which its tendon is attached to the heel 

 bone is the insertion ; the other, less movable end is the origin. 

 From what bone does it arise, and by how many tendons ? Cut 

 across the muscle at its thickest part, the belly of the muscle, 

 and study its structure. Note that the tendons at the ends 

 of the muscle are continuous with the muscle sheath and 

 with the partitions running through the muscle. Pull the tendon 

 toward the body ; this straightens, or extends, the foot ; the calf 

 muscle is therefore called an extensor muscle. With the handle 

 of the scalpel loosen the muscle on the front of the shin bone ; 

 prove that its action is to bend, or flex, the foot. It is a flexor. 

 Find its origin and insertion. 



4. By further dissection find how the different movements of 

 the toes are effected. 



5. Cut into the knee joint. Observe the liquid, the synovia, 

 which oils the joint. Rub a drop of it between the thumb and finger. 



6. Observe the glistening bands which hold the ends of the 

 bones together. These are the ligaments. Carefully study 

 their arrangement and uses. 



