484 DISSECTION OF THE ABDOMEN. 



consists of a thin membrane, lined by flattened epithelium, with plexuses 

 of bloodvessels ramifying on the exterior. 



Bloodvessels and nerves of the testicle. The branches of the spermatic 

 artery supply offsets to the epididymis, and pierce the back of the testicle 

 to enter the posterior part of the mediastinum. The vessels are finely 

 divided in the vascular structure lining the interior of the tunica albugi- 

 nea; and offsets are continued on the fine septa to the seminal tubules, on 

 which they are distributed in capillary plexuses. 



The spermatic vein begins by radicles in the plexuses around the seminal 

 tubes, and issues from the gland at the posterior part, being there joined 

 by veins from the epididymis. As it ascends along the cord its branches 

 form the spermatic plexus ; it joins the vena cava on the right side, and 

 the renal vein on the left (p. 492). 



The arrangement of the lymphatics in the testicle is unknown ; external 

 to that body they ascend on the bloodvessels, and join the lumbar glands. 



The nerves are derived from the sympathetic, and accompany the arte- 

 ries to the testis : their ending has not been seen. 



Vessels of the vas deferens. A special artery is furnished to the excre- 

 tory duct from the upper or lower vesicle, and reaches as far as the testis, 

 where it anastomoses with the spermatic artery. Veins from the epididy- 

 mis enter the spermatic vein. The nerves are derived from the hypogastric 

 plexus. 



SECTION V. 



DIAPHRAGM WITH AORTA AND VENA CAVA. 



Directions. After the body is replaced in its former position on the 

 Back, the student should prepare first the diaphragm, next the large ves- 

 sels and their branches, and then the deep muscles of the abdomen. 



Dissection. For the dissection of the diaphragm it will be necessary to 

 remove the peritoneum, defining especially the central tendinous part, and 

 the fleshy processes or pillars which are fixed to the lumbar vertebrre. 

 Whilst cleaning the muscle the student should be careful of the vessels and 

 nerves on the surface, and of others in and near the pillars. 



On the right side two aponeurotic bands or arches, near the spine, 

 which give attachment to the muscular fibres, should be dissected : one 

 curves over the internal muscle (psoas); the other extends over the exter- 

 nal muscle (quadratus), and will be made more evident by separating the 

 fascia covering the quadratus from it. 



The DIAPHRAGM (fig. 168, A ) forms the vaulted movable partition be- 

 tween the thorax and the abdomen. It is fleshy externally, where it is 

 attached to the surrounding ribs and the spinal column, and has its tendon 

 in the centre. 



The origin of the muscle is at the circumference, and is similar on each 

 aide of the middle line. Thus, it is connected by fleshy slips with the pos- 

 terior part of the xiphoid cartilage, and the inner surface of the six lower 

 ribs ; with two aponeurotic arches between the last rib and the spinal 

 column one being placed over the quadratus lumborum, and the other 

 over the psoas muscle ; and, lastly, it is connected with the lumbar verte- 

 brae by a thick muscular part or pillar. From this extensive origin the 



