SECT. 82.] MUSCULAR SYSTEM. I49 



invest single muscles or groups of muscles with tlicir tendons, 

 and have generally the structure of tendons and aponeuroses, 

 especially where they are connected with muscular fibres and 

 tendons; frequently, however, they contain, in their connective 

 tissue, a larger number of fine elastic fibres, or even a very close 

 network of larger elastic elements. The latter structure occurs 

 wherever the fascia? are destined to form a firm enveloping mem- 

 brane for the muscles without impeding them in their various 

 changes of form, particularly, therefore, in the middle of the 

 limbs. 



B. Ligaments of the Tendons. — Besides certain ligamentous 

 parts of the fascia?, which, being attached to bones, surround the 

 tendons or otherwise confine them, there are the so-called tendinous 

 sheaths (Ugg. vaginalia tendinum), as, for example, those of the 

 tendons of the flexors of the fingers and toes, where they consist 

 of numerous small bands arranged in succession, and strengthening 

 the synovial sheaths. Other ligaments comprehended in this sec- 

 tion are the lig. carpi proprium, the trochlea, and the retinacula 

 tendinum. 



C. Synovial Bursa? and Synovial Sheaths. — Wherever muscles or 

 tendons, in performance of their movements, rub against hard 

 structures (bones, cartilages) or against other muscles, tendons and 

 ligaments, there are found between the parts concerned spaces 

 filled with a small quantity of viscid fluid, which, according to Vir- 

 chow, is not mucus, but a substance very similar to colloid matter. 

 These spaces are usually regarded by anatomists as being lined by 

 a special membrane, the synovial membrane. But, in point of fact, 

 only the smaller number of these spaces are covered throughout by 

 a continuous membrane, the majority being destitute of it in 

 many places. AVith regard to the synovial bursa?, those of the 

 muscles (psoas, iliacus, deltoideus, etc.) approach most to the con- 

 dition of continuous sacs; whereas those of the tendons exhibit 

 only an incomplete membrane, and are destitute of it precisely on 

 those parts which glide upon each other. The same observation ap- 

 plies to the synovial sheaths, among which only the common sheaths 

 of the flexors of the fingers and toes present, in a certain measure, 

 the form of a so-called serous sac, although, even here, there are 

 many parts of the tendinous surface devoid of all membranous in- 

 vestment. In most of the synovial sheaths, and in many synovial 

 bursa?, there are occasionally reddish, fringed processes, which, in 

 form and structure, entirely resemble those in the joints, and are 

 nothing but vascular processes of the synovial membrane. 



