PRACTICUM IV. THE ABDOMEN OF THE CAT. 



PLATES REQUIRED : VIII, IX, X, XI. 



Si. Preparation of the Specimen. See Pract. Ill, 38. A little 

 cephalad of the dorsal attachment of the diaphragm, transect the spine, 

 etc. , either summarily with a hatchet or cleaver as with the neck (Pract. 

 Ill, i), or more instructively as follows : 



a. Clear the soft part (excepting the aorta, postcava and esophagus) from the ventral 

 side of the spine 3-5 cm. from the diaphragm. 



b. Press the probe point against the spine at short intervals till it enters, indicating 

 the location of an intervertebralfibro-cartilage. 



c. Divide the spinal muscles at this level till bone is reached. 



d. Push the arthrotome transversely into the cartilage and cut it so that the vertebral 

 centrums separate slightly ; Plates I and VIII. 



e. Flex the spine dorsad so as to increase the space ; note the myel and divide it with 

 a scalpel. 



f. Flex the spine still more dorsad from side to side, so as to indicate the location of 

 the rather complex joints between the overlapping processes of the vertebras. Use the 

 arthrotome carefully so as to complete the separation. 



g. When practicable adjacent students should have cats of opposite 

 sexes. 



2. The Diaphragm. The thoracic surface of the diaphragm (PL 

 VIII) should present a marked convexity into the thorax and 4 be approxim- 

 ately smooth ; if it is wrinkled, in the lateral parietes of tile abdomen 

 cut a small slit that may admit the blow-pipe, and inflate the abdomen 

 till the diaphragm is as desired ; prevent the escape of the air by means 

 of a compressor (spring clothes-pin or garment-clasp). 



3. Place the specimen on its back and steady it by means of the 

 leaden cradle. 



a. This is a piece of sheet lead about the size of this page (16X25 cm. 6.5X10 in.) 

 bent across its length so as to form a W with rounded angles ; when inverted it makes a 

 "cradle" which may be adjusted to the size of the cat and the position desired. 



4. Make a drawing of the diaphragm, etc. ; consult PI. VIII and its 

 description ; but draw the specimen and only the featiires it presents. 



a. The peripheral portion, next the spine, ribs and sternum, is 

 muscular. 



b. The fasciculi converge toward a non-muscular area, the CENTRAL 

 TENDON ; this varies somewhat in size and form but is commonly cres- 

 centic, cordate or triradiate. It is sufficiently transparent for the abdom- 

 inal viscera to be seen dimly through it. 



c. The diaphragm is traversed by three tubes, already seen and 

 drawn in Pract. Ill, viz., the POSTCAVA, just ventrad of its middle, and 

 probably full of blood ; the AORTA, near the spine and probably empty ; 

 the ESOPHAGUS, fleshy, corrugated, nearly midway between the two. The 

 phrenic nerves should be looked for ; if pulled gently cephalad there may 

 be recognized some of their branches radiating in the muscular portion of 

 the diaphragm. They should have been represented on PI. VIII. 



d. The cut edge of the PLEURA lining the other portions of the 

 thoracic parietes should be represented by a continuous, sharp line. It is 

 reflected upon the diaphragm and covers most of its surface ; but sinis- 

 trad of the POSTCAVA is an area corresponding to the location of the 

 azygous or fourth lobe of the right lung, about which, under favorable 

 conditions, may be traced the cut or torn edges of the pleura which was 

 reflected to form the ventral and dorsal SEPTUMS (Pract. Ill, 30). 



