536 PHYSIOLOGY/ 



within the protoplasm so as to form an almost continuous layer 

 beneath the sarcolemma. 



Relation to Tendons. When a muscle terminates in a tendon, it 

 is found that the muscular fibers either run in the same direction as 

 the fibers of the tendon or join with the tendon at an acute angle. 

 According to Toldt, the delicate connective-tissue elements covering 

 the several muscular fibers pass from the latter directly into the con- 

 nective-tissue elements of the tendon. According to another author, 

 the ends of the muscular fibers are believed to be fastened to the 

 smooth tendons by means of a special cement. However, it is prob- 

 able that the areolar tissue which lies between the tendon-fibers 

 passes between the ends of the muscular fibers to be gradually lost 

 in the interstitial connective-tissue. 



Blood-vessels of Muscle, The blood-vessels to the muscles are 

 very numerous. The average muscle leads such an active life that 

 its nourishment and repair material must be in proportionate rela- 

 tion. Unlike the organs, as the kidney and spleen, which usually 

 are supplied by one artery and vein, muscles receive several branches 

 from various arteries which pierce the muscle at different points 

 along its course. 



The artery and vein usually are in close proximity, being held 

 in position by the connective tissue upon the perimysium. The capil- 

 laries lie between the muscle-fibers in the endomysium, but outside 

 of the sarcolemma. Here the capillaries are small, and form a fine 

 network with narrow, oblong meshes, which are stretched out in the 

 direction of the fibers. The capillaries have both longitudinal and 

 transverse vessels. The lymph that is destined to support the sar- 

 cous substance must pass through the sarcolemma to reach the same. 



Muscle Nerve-supply. The nerve-supply to muscles is both 

 motor and sensory. Each muscle-filer receives a motor nerve-fiber. 

 The trunk of the motor nerve, as a rule, enters the muscle at its 

 geometrical center (Schwalbe) ; thus, the point of entrance in a long, 

 spindle-shaped muscle lies near its middle. At this "geometrical 

 center" there is the point of least disturbance during contraction of 

 the muscle. After the trunk of the nerve pierces the muscle it pro- 

 ceeds to divide dichotomously until there are just as many nerve- 

 fibers as muscle-fibers. A nerve-fiber now enters each muscle-fiber, 

 to do which, of course, it must pierce the sarcolemma. The point 

 of entrance forms an eminence known as Doyere's eminence, or 

 motorial end-plate. At this point the sheath of the nerve-fiber 

 becomes continuous with the sarcolemma. The eminence itself con- 



