MUSCULAR SYSTEM. 277 



The muscles are connected with other parts of the body 

 almost always by means of tendons. These consist, as has been 

 stated, of connective-tissue fibrils, which are joined together by 

 means of interfibrillar cement substance to form primary bundles. 

 Many of these are combined by interfascicular cement substance 

 to make up secondary tendon bundles (Fig. 203). The char- 

 acteristic tendon cells lie between the primary bundles. The 



FIG. 203. 



Tenc 



tissue septa 



Connective- Tendon cells 





L <&. S --> 

 Part of a cross-section of a human tendon (popliteal muscle). X 210. 



secondary bundles are surrounded by loose connective tissue 

 containing elastic fibres and joined together to form tertiary 

 bundles. The whole tendon is surrounded by a connective- 

 tissue capsule, the so-called peritenonium. The tendon sheath 

 consists of connective tissue lined on the inner surface with a 

 layer of flat cells. 



The intimate connection between muscle and tendon is 

 brought about by the direct transition of the perimysium into 

 the connective tissue of the tendon (Fig. 204). In cases in 

 which the muscle is fastened to the periosteum or fasciae, the 

 perimysium alone effects the union by passing over directly 

 into the periosteum or fascia. 



The blood-vessels of tendons are not abundant. They run 

 in the loose connective tissue between the tendon bundles. 

 The lymph-vessels form a rich plexus on the surface of the 

 tendon. The nerves end on the tendons partly by means of 



