CHAPTER III. 



ON THE MUSCLES. 



MUSCLES are the moving organs of the animal frame : they con- 

 stitute by their size and number the great bulk of the body, upon 

 which they bestow form and symmetry. In the limbs they are situated 

 around the bones, which they invest and defend, while they form to 

 some of the joints a principal protection. In the trunk they are spread 

 out to enclose cavities, and constitute a defensive wall capable of yield- 

 ing to internal pressure, and again returning to its original form. 



Their colour presents the deep red which is characteristic of 

 flesh, and their form is variously modified, to execute the varied 

 range of movements which they are required to effect. 



Muscle is composed of a number of parallel fibres placed side by 

 side, and supported and held together by a delicate web of 

 cellular tissue ; so, that if it were possible to remove the muscular 

 substance, we should have remaining a beautiful cellular frame- 

 work, possessing the exact form and size of the muscle without its 

 colour and solidity. Towards the extremity of the organ the mus- 

 cular fibre ceases, and the cellular structure becomes aggregated 

 and modified, so as to constitute those glistening fibres and cords 

 by which the muscle is tied to the surface of bone, and which are 

 called tendons. Almost every muscle in the body is connected 

 with bone, either by tendinous fibres, or by an aggregation of those 

 fibres constituting a tendon ; and the union is so firm, that, under 

 extreme violence, the bone itself rather breaks than permits of the 

 separation of the tendon from its attachment. In the broad muscles 

 the tendon is spread so as to form an expansion, called aponeurosis 

 (owro, long ; vsugov* nervus a nerve widely spread out). 



Muscles present various modifications in the arrangement of their 

 fibres in relation to their tendinous structure. Sometimes they are 

 completely longitudinal, and terminate at each extremity in tendon, 

 the entire muscle being fusiform in its shape ; in other situations 

 they are disposed like the rays of a fan, converging to a tendinous 

 point, as the temporal, pectoral, glutei, &c., and constitute a radiate 

 muscle. Again, they are penniform, converging like the plumes of 

 a pen to one side of a tendon which runs the whole length of the 

 muscle, as in the peronei ; or bipenniform, converging to both sides 

 of the tendon. In other muscles the fibres pass obliquely from the 

 surface of a tendinous expansion spread out on one side, to that of 

 another extended on the opposite side, as in the semi-membranosus ; 

 or they are composed of penniform or bipenniform fasciculi as in the 

 deltoid, and constitute a compound muscle. 



The nomenclature of the muscles is defective and confused, and 

 is generally derived from some prominent character which each 



* The ancients named all the white fibres of the body nt/ga ; the term has since been 

 limited to the nerves. 



