THE MUSCULAR SYSTEM. 239 



nuclei, and 2 to 6 minute opaque fat-granules, occasionally occur ; the 

 cells afterwards disappear, and the nuclei, which, on the addition of 

 acetic acid, appear a little yellowish, become more and more elongated, 

 and transformed into long, slender, straight, or slightly-curved fibres, 

 which are, finally, conjoined into long nuclear fibres; these fibres, how- 

 ever, upon the whole are rare. The elongated nuclei are not always 

 placed in a straight line, one behind the other, but frequently in an ob- 

 lique, and in various other directions. In this way are produced serpen- 

 tine nuclear fibres, which, even when fully formed, are still surrounded 

 with isolated fat-granules, and lie as it were in vacant spaces in the con- 

 nective, tissue. In this case, consequently, the nuclear fibres are not 

 formed from the nuclei of the cells, from which the connective tissue is 

 formed, but from special cells of a temporary nature; which circum- 

 stance, were the fact of general application, would make it intelligible, 

 that nuclear fibres may both surround the secondary fasciculi of connec- 

 tive tissue, and also exist without any such tissue (membranous reticular 

 expansions of nuclear fibres, "Micr. Anat.," II. 1, p. 226)]. 



B. Ligaments of the tendons. The tendons are retained in their posi- 

 tions by various ligaments. Independently of certain ligamentous por- 

 tions of the fasciae, which, being attached to the bones, form tubular 

 processes around tendons, or otherwise confine them, there are the so- 

 called tendinous sheaths (lig. vaginalia tendinum), as for instance on the 

 flexor tendons of the fingers and toes, where they are formed of nume- 

 rous successive narrow bands, which in these situations serve to strengthen 

 the mucous sheaths. Other ligaments to be referred to this class, are 

 the lig. carpi proprium, the trochlea, and the retinacula tendinum. 



0. Mucous bursce and sheaths, bursar mucosce et vaginae synoviales. 

 Where muscles or tendons, in their movements, rub upon hard parts 

 (bones, cartilages), or on other muscles, tendons, and ligaments, there 

 are found, between the parts in question, spaces filled with a slightly 

 viscid fluid, which, according to Virchow (Wurzb. "Verb." II. 281), 

 contain not mucus, but a material very similar to colloid matter, and 

 which anatomists have been used to regard as lined with a special mem- 

 brane, a synovial membrane. These spaces are said to constitute closed 

 sacs of a rounded or elongated form, which either simply invest the 

 opposed surfaces of bones and tendons, bones and muscles, &c., bursce 

 mucosce; or in the form of double, although connected tubes, cover at 

 the same time the surface of the tendons, and of the parts between 

 which the tendons play, vagince synoviales. The truth of the matter 

 is this, that it is only the smallest of these spaces which are lined with 

 a continuous membrane; most of them are in many situations without 

 such a lining. With respect to the mucous bursse, those appertaining to 

 the muscles (psoas, iliacus, deltoid, &c.), are, eminently, to be consi- 

 dered as continuous sacculi, whilst in those belonging to the tendons, a 



