42 ANATOMY OF THE RABBIT 



muscle and that in order to be used intelligibly there must be 

 a common agreement on the applications of the two terms. If 

 the student will recall having seen screen doors closed by means 

 of a long, coiled spring, or piece of strong elastic (which he will 

 assume is a muscle), one end of which was attached to the 

 doorpost and the other to a point on the door near the latch, 

 he will be able to comprehend the rules underlying the distinc- 

 tion between origin and insertion of muscles in man and the 

 rabbit. In this explanation the door post (to which the 

 hinges of the screen door are fastened) furnishes the fixed, or 

 proximal attachment for one end of the '^ muscle " (the spring) — 

 the origin, while the freely moving edge of the door furnishes 

 the distal or movable attachment for the '' muscle" (the 

 spring) — the insertion. The term attachment may mean 

 either origin or insertion, but does not differentiate between 

 these terms. The free sides, or edges, of a muscle are called 

 margins or borders and the area between the two margins, the 

 bulging part, is called the belly of the muscle. 



E. THE NAMES OF MUSCLES 



The names of muscles are usually derived from the origin, 

 insertion, situation, direction of fibers, form, or function of 

 the muscle, and for this reason, the name designates not only 

 the muscle, but often also suggests its relations and functions. 



F. SKINNING THE RABBIT 



The skin is a natural protection for the soft tissues, and 

 since several days will be spent in dissecting the muscles, it is a 

 good plan to remove the skin from only the region in which the 

 dissection is being done and to leave it in place on the remaining 

 regions of the specimen so as to delay exposure of those parts to 

 active dessication as long as possible. For this reason, it is the 

 best plan to remove the skin from the various parts of the body 

 as directed in the following instructions. 



