THE MUSCLES. 79 



communis digitorum muscle signifies by its name that it is 

 the common extensor of the digits. 



DISSECTION OF THE MUSCLES. 



Since the other systems are of more importance from the 

 standpoint of comparative anatomy and physiology than the 

 muscular, only the more important muscles will be described. 

 Great care should be exercised in removing the skin of the 

 cat, in order that such superficial muscles as the platysma 

 myoides on the neck and side of the face, and occipito- 

 frontalis, may not be cut away. The skin is attached to 

 the underlying muscles by the superficial fascia, a fibrous 

 areolar tissue, which contains the subcutaneous fat more or 

 less abundant in all specimens. The deep fascia is the 

 fibrous and membranous layer of dense tissue lying close 

 against the muscles and dipping down between them. The 

 stronger parts of this fascia are called aponeuroses. 



Directions for Dissection. Dissection does not mean 

 the cutting up, but the intelligent separation of one organ 

 from another and the removing of known portions to study 

 the deeper structures more carefully. The muscles should 

 not be cut loose from their origin or insertion, but merely 

 separated from each other by cutting the deep fascia in 

 the longitudinal direction of the muscle. If it is neces- 

 sary to remove a muscle for displaying those beneath, it 

 should be cut transversely in the middle and the two parts 

 reflected. No portion of a muscle or other tissue should be 

 removed without knowing what it is and noticing carefully 

 its relation to the surrounding parts. The specimen under 

 dissection should be securely nailed to the tray so that the 

 muscles are made tense. When the parts become dry, they 

 should be thoroughly wet with water. If the formalin in 

 which the specimen has been preserved is irritating to the 

 mucous membrane of the dissector, a half liter of 5% 

 ammonium hydrate should be poured over the specimen. 



