Practicum I. The Skin Muscles. 



Fig. i. Diagram of a Cat as prepared for practicum purposes. The hair was removed 

 by immersion in water at about 80 C. (,176 F. ). The skin and most of the flesh have been 

 cut from the legs and hips, and the tail abbreviated. At the right heel is seen a part of 

 the TENDO ACHILLIS, the large tendon by which the muscles of the "calf of the leg" 

 were inserted. The special object of the figure is to indicate the crucial incision by means 

 of which the skin muscle is to be exposed. 



a. When the four flaps of skin have been lifted they may be cut off 

 with the scissors. There will then be exposed a quadrangular area of the 

 SKIN-MUSCLE, recognizable by its pale red color and from the sparseness 

 of its fascicles (bundles of fibers). Even if it has been divided by the 

 crucial incision it may be cut out as a thin sheet, separated by FAT and 

 CONNECTIVE TISSUE from an ental, thicker muscle, the LATISSIMUS, 

 whose fascicles run in nearly the same direction ; see PL II, just dorsad 

 of the word ABDOMEN. 



b. If the foregoing operations fail on the left side, repeat on the right 

 with additional precautions. 



c. On the neck, from a point about midway of its length and dorso- 

 ventral diameter (on PI. II coinciding nearly with the dorsal end of the 

 line between the Eand the c of NECK), cut caudad along the middle of the 

 left side to the root of the tail, or to the cut margin of the skin in case it 

 and the flesh have been removed from the hips and legs. This incision 

 should divide both the skin and the skin-muscles. On the neck and 

 shoulder no great harm would result from cutting too deeply, but on the 

 thorax care should be taken not to cut the latissimus, and on the abdo- 

 men there is danger of opening that cavity prematurely. 



d. Grasp the cut edge of skin and skin-muscle, at the dorsal side of 

 area exposed in (a\ and dissect them up from the latissimus, remember- 

 ing that the latter has a free margin extending obliquely toward the arm 

 in continuation of the line shown in PI. II. On the neck and shoulders 

 some irregularities and adhesions will be encountered, but no serious dif- 

 ficulties. In this way "skin" the left side dorsad as far as the meson. 



13. Do the same for the ventral half of the left side, noting three fea- 

 tures : (2) The MAMMARY GLAND, a whitish, lobulated organ, quite large 

 in nursing females, and extending the whole length of the abdomen and 

 upon the thorax ; (2) the series of NIPPLES connected therewith ; (3) the 

 narrowing and thickening of the latissimus near the arm ; (4) the 

 PECTORAL MUSCLES, thicker and darker than the skin-muscles and having 

 a direction from the meson latero-cephalad (PI. III). 



