98 



THE HUMAN MOTOR 



iii. LIMBS. 



A. Upper Limbs. 



Deltoid Biceps of the arm Brachialis anticus Coracro- 

 brachialis Triceps Extensor radialis Supinator longus- 

 Flexors and extensors of the fingers. 



B. Lower Limbs. 



Vastus externus and internus Rectus femoris Adductor 

 longus and magnus Sartorius gluteus maximus, medius, and 

 minimus. Obturator externus and internus Pectmeus 

 Gastrocnemius Semimembranous Soleus Tibialis postiens. 

 Extensors and abductors of the toes. 



Most of the muscles that we have studied statically have 

 definite shapes, more or less distinct ; some are short and thick, 

 others long. In complete repose they are " relaxed " and develop 

 their full length. This is, however, infrequent. 



71. (iii.) Tendons and Cartilages. Tendons are organs made of 

 elastic fibre, which are fixed at the extremity of 

 muscles, in continuation of the envelope with 

 which they are covered. They are more com- 

 pact than muscles, and by adhering to the 

 rugose surfaces of the bones, they serve as solid 

 points of attachment. They are also denser 

 and only contain, on an average, 67% of water. 

 A well-known example of tendons is the 

 " Achilles tendon " which terminates the lower 

 calf muscles, and is fixed to the heel bone (os 

 calcis) (fig. 106). The resistance of tendons 

 was measured by Wertheim, and later by 

 Triepel. The former obtained the following 

 values for the plantar tendon of man : 



t 



Tm. 106. 



