THE MUSCLES. 



41 



at each end. They are of various shapes, according .to 

 their position and use. Some are long, some short : some 

 are round, and some flat. In the living body, all the 

 muscles of a limb are bound together 

 and covered by fibrous tissue. 



5. Voluntary muscles are commonly 

 attached to a bone, at one or both ends, 

 by means of a tendon or aponeurosis. 

 A tendon is a glistening cord of fibrous 

 tissue. It is tough, and does not stretch. 

 An aponeurosis differs from a tendon 

 in being flat. If the muscle is flat, it 

 ends in an aponeurosis : if it is round, 

 it tapers down to a tendon. 



6, There are more than five hun- 

 dred muscles in the body. Most of 

 them are in pairs, the two sides of the 

 body being alike. The smallest is the 

 stapedius, a muscle in the ear, which 

 is only one-sixth of an inch in length : 

 the longest is the sartorius, which ex- 

 tends from the hip to the leg below 

 the knee, and is over eighteen inches 

 in length. 



The biceps of the arm has two heads, 

 both arising from the shoulder-blade, 

 and is inserted into the radius just below the elbow. 

 The great muscles which pass from the breast-bone to 

 the upper end of the arm are called pectorals. The 

 gastrocnemius constitutes a large part of the calf of the 

 leg. Its tendon, called the tendon of Achilles, is inserted 

 into the heel, and is the largest tendon in the body. 



