234 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM 



Tendo Achillis, broad at first, contracts to within 1| inches 

 of the heel, then expands, and is inserted into the middle and 

 lower parts of the posterior surface of the tuberosity of the 

 os calcis, a bursa having all the characters of a synovial mem- 

 brane, with vascular and fatty synovial tufts, separating it 

 from the upper part of this surface. 



2. M. Plantaris. Origin, femur above the external condyle 

 and from the posterior ligament of the knee-joint. Muscular 

 belly 3 to 4 inches long, and the long, slender tendon turns 

 in between the gastrocnemius and soleus to the inner border 

 of the tendo Achillis, and inserted by its side into the calcaneum 



May join tendo Achillis, end in fascia of the leg or internal 

 annular ligament, or be enclosed in the tendo Achillis. Absent 

 in 7.5 per cent. It is the remains of a superficial flexor of the 

 digits, like the palmaris longus. 



3. M. Popliteus. Origin, round tendon, 1 inch long, from 

 the groove on the outer surface of the external condyle of 

 the femur, within the capsule of the joint, in contact with the 

 semilunar cartilage, and by muscular fibers from the ligamen- 

 tum popliteus arcuatum. Fibers pass down and are inserted 

 into the triangular surface of the tibia above the oblique line, 

 and into the aponeurosis over the muscle. The tendon is 

 in the groove on the femur only in full flexion. Henle gives 

 origin below and insertion above. 



The Deep Muscles (Flexors) 



1. M. Flexor Longus Digitoruni Pedis (Perforans). Origin, 

 inner portion of the posterior surface of the tibia for the middle 

 two-fourths of its length, from the aponeurosis over the tibialis 

 posticus. Descends behind the internal malleolus, passes 

 forward and obliquely outward, having crossed the tibialis 

 posticus tendon in the leg, and now crossing that of the flexor 

 longus hallucis, in each case superficially. It divides into four 

 parts for terminal phalanges of the four lesser toes. The whole 

 arrangement of the vincula accessoria, etc., is as for the fingers. 



2. M. Tibialis Posticus, beneath the two long flexors. 

 Origin, posterior surface of the interosseous membrane, outer 

 part of the posterior surface of the tibia below the oblique 

 line to the middle of the bone, whole inner surface of the fibula, 

 and from the aponeurosis over it. Tendon along the inner 



