12 MOTION MUSCLE AND NEKVE. 



In order to understand the subject better, let us look at 

 the muscles of a rabbit's leg. The dressed rabbits found in 

 the markets will serve very well, but it is better not to have 

 the skin removed until just before studying the muscle. Two 

 students maj 7 " conveniently work together. 



Muscle and Nerve. 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 termi- 

 nation 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 scal- 

 pel. Remove any fat that may be in the way. Deeply im- 

 bedded 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 ? 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 ex- 

 tends, 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 in- 

 sertion. 



