122 



THE HUMAN JBODT. 



consists of a proper striped muscular tissue, which is its es- 

 sential part, but which is supported by connective tissue, 

 nourished by blood-vessels and lymphatics, and has its ac- 

 \tivity governed by nerves; so that a great variety of things 

 go to form the complete organ. 



A loose sheath of areolar connective tissue, called the 

 | perimysium, envelops each muscle, and from this parti- 

 tions run in and subdivide the belly into bundles orfasci- 

 \ cult which run from tendon to tendon, or for the whole 

 length of the muscle when it has no tendons. The coarse- 

 ness or fineness of butcher's meat depends upon the size of 

 these primary fasciculi, which differs in different muscles 

 of the same animal. These larger fasciculi are subdivided 



by finer connective-tissue- 

 membranes into smaller 

 ones (as shown in Fig. 52, 

 which represents a few pri- 

 mary fasciculi of a muscle 

 and the secondary fasciculi 

 into which these are di- 

 vided), each of which con- 

 sists of a certain number of 



muscular fibres bound to- 

 showing the secondary fasciculi of which gether by very fine con- 

 nective tissue and envel- 

 microscopic blood - vessels. 

 Where a muscle tapers the fibres in the fasciculi become- 

 less numerous, and when a tendon is formed disappear 

 altogether, leaving little but the connective tissue. 



Histology of Muscle. For the present we need only 

 concern ourselves with the muscular fibres. Each of these is 

 from eight to thirty-five millimeters (-J- to 1J inch) long, 

 but only from 0.034 to 0.055 mm. ( T |^- to ^ inch) in 

 diameter in its widest part, and tapering to a point at each 

 (end. Hence in long muscles with terminal tendons, no 

 fibre runs the whole length of a fasciculus, which may be a 

 foot or more long, but the fasciculus is made up of many 

 successive fibres, the narrow end of each fitting in between 

 the ends of those which follow it. In short or penniform 



FIG. 52. A small bit of muscle com- 

 posed of four primary fasciculi. A, 

 natural size; B. the same magnified, 



the primary are composed. 



oped in a close network of 



