Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
pages 363
| muscle in succession or at different times. Most muscles are, however, in a mechanical sense units. But in either case the muscle fibers constitute the elementary motor elements. |
 |
FIG. 361– No caption. (See enlarged image) |
 |
FIG. 362– No caption. (See enlarged image) |
 |
FIG. 363– No caption. (See enlarged image) |
The Direction of the Muscle Pull.—In those muscles where the fibers always run in a straight line from origin to insertion in all positions of the joint, a straight line joining the middle of the surface of origin with the middle of the insertion surface will give the direction of the pull (Fig. 361). If, however, the muscle or its tendon is bent out of a straight line by a bony process or ligament so that it runs over a pulley-like arrangement, the direction of the muscle pull is naturally bent out of line. The direction of the pull in such cases is from the middle point of insertion to the middle point of the pulley where the muscle or tendon is bent. Muscles or tendons of muscles which pass over more than one joint and pass through more than |