SECT. 79, 80.] MUSCULAR SYSTEM. I45 



sheaths form a connected system, the perimysium, of which the 

 part externally surrounding the entire muscle is distinguished 

 as perimysium externum, or the muscular sheath, strictly so 

 called, from the portion immediately inclosing the larger and 

 smaller bundles, and the muscular fibres — the perimysium in- 

 ternum. The thickness of the secondary muscular bundles varies 

 from £"' to Y't that of the tertiary, and still larger bundles, 

 which are most obvious in muscles of apparently coarse texture 

 {glutceus ma.vimus, deltoideus), is so variable, and the division of 

 these larger constituents of a muscle so arbitrary, that there is 

 nothing specially to be said concerning them. The perimysium 

 consists of ordinary connective tissue, and fine elastic fibres. In all 

 muscles, especially in those of lax structure, fat-cells often occur 

 in large numbers in the perimysium. 



§ 79. Connection of the Muscles with other parts. — The muscular 

 fibres are connected with the moveable structures, the bones, 

 cartilages, articular capsules, the skin, etc., either immediately or 

 by the interposition of fibrous parts, such as tendons, aponeuroses, 

 certain portions of muscular fascise and ligaments. Those muscles, 

 which are entirely, or only at one extremity attached without the 

 intervention of tendons, constitute, upon the whole, the minority. 

 Where muscular fibres arise immediately from bone (obliqui, iliacus, 

 psoas, glutcei, etc.) or from cartilage (transversus abdominis, dia- 

 phragma), or are immediately inserted into these parts (serrati, 

 omo-hyoideus, sterno-hyoideus, muscles of the ear), they proceed 

 only as far as the periosteum or perichondrium, and terminate with 

 blunt extremities upon these membranes, into whose fibres they 

 are not continued, nor do they come into immediate contact with 

 the bones and cartilages. "When muscles extend to the skin, 

 they either lie flat underneath it without any direct connection, or 

 spread out in its substance in form of larger and smaller bundles 

 (muscles of the face), and appear to be attached to its bundles of 

 connective tissue ; as has been observed in the levator labii supe- 

 riors of the rat, by Busk and Huxley. 



§ 80. The tendons are glistening, white, or yellowish structures, 

 almost entirely composed of connective tissue. They are divided, 

 according to their form, into the funicular, or proper tendons, and 

 the membranous ap>oneuroses (centrum tendineum, galea cranii, 

 tendons of the abdominal muscles, latissimus, cucullaris, etc.). 

 These two forms — not strictly separated by external characters — 



