/. , 



THE MUSCULAR SYSTEM. 243 



special envelope of connective tissue, and, several together, 

 united by stronger membranes into tertiary fasciculi, which, 

 lastly, in a greater or less number, unite and constitute the 

 separate bellies of the muscle, or muscles themselves. If the 

 muscular fasciculi are placed in the same plane, they constitute 

 the membranous or flat muscles ; and when disposed in a thick 

 bundle, the elongated or columnar muscles. The muscles con- 

 sequently are aggregations of numerous, larger and smaller 

 secondary and tertiary fasciculi, the sheaths or perimysium of 

 which constitute a y\%. 94, 



connected system, in 

 which that portion 

 which surrounds the 

 entire muscle, as the ffc/5 

 perimysium externum >^ 

 or muscular sheath vt§ 

 [vagina muscularis), %E 

 is to be distinguished 

 from the more inter- c 



nal elements imme- ?' 



diately surrounding the larger and smaller fasciculi and the 

 muscular fibres — the perimysium internum. The thickness of 

 the secondary fasciculi varies from ~ to |'"; that of the tertiary 

 and still larger bundles, which are most evident in muscles 

 with coarse fibres (gluttons maximus, deltoideus), is so various, 

 and the division of the muscle in these more remote con- 

 stituents is so arbitrary, that there is nothing specially to be 

 said with respect to them. 



The muscular sheaths or envelopes, perimysium, composed of 

 connective tissue, which are for the double purpose of conveying 

 the vessels and nerves of the muscles, and of connecting the 

 muscular fibres and supporting them when in action, vary in 

 thickness according to the greater or less size of the groups of 

 fasciculi surrounded by them. They are always, however, 

 delicate, dull-white, non-glistening tunics, consisting of common 

 connective tissue, and minute, isolated or anastomosing elastic 

 fibres, of at most 0001"' in thickness, the latter occurring in 



Fig. 94. Transverse section from the rectus capitis anticiis major of Man, x 350 

 diam.: a, external perimysium ; b, perimysium internum; c, primitive fasciculus and 

 secondary muscular fasciculus. 



