DEEP AND POSTERIOR PARTS OF THE ABDOMEN. 1075 



removal of the surrounding adipose tissue not to injure their substance, 

 which is easily torn (p. 939) : after they have been carefully cleaned, these 

 bodies may be examined by incisions into their substance. 



The aorta and inferior vena cava are then to be dissected, and also the 

 common and external iliac arteries and veins, together with the kidneys and 

 ureters. The branches of the aorta to be examined are the inferior phrenic, 

 the cceliac axis, the superior mesenteric, the suprarenal, the renal, the 

 spermatic, the inferior mesenteric, the origins of the four pairs of lumbar 

 arteries, and, continuing the direction of the aorta from its point of bifurca- 

 tion, the middle sacral artery. The two common iliac arteries and veins 

 7nust at this time be cleaned, also the ureters ; and the dissection may be 

 carried down along the external iliac vessels, as far as the origin of the epi- 

 gastric and circumflex iliac arteries ; in doing which the relations of the 

 iliac arteries and veins will be carefully observed (pp. 418, 473, and 477). 

 The position and relations of the kidneys are now to be examined, and 

 more particularly the position of the renal artery, renal vein, and ureter, 

 as they enter the gland (p. 926). The kidneys having been removed from the 

 body, are to be opened by a transverse vertical section, to exhibit the pelvis, 

 calyces, and pyramids, the cortical and internal tubular substances, and the 

 Malpighian glomeruli : the fibrous tunic which invests the kidney is also to 

 be observed. The receptaculum chyli or commencement of the thoracic 

 duct will be found beneath the right crus of the diaphragm (p. 487), as 

 also the commencement of the vena azygos in connection with some of the 

 lumbar veins (p. 469). 



7. Upper and Posterior Wall of the Abdomen. The diaphragm is now 

 to be dissected (p. 243). Anteriorly will be found its attachments to the 

 six lower ribs interdigitating with those of the trausversalis muscle ; poste- 

 riorly will be found the two crura and the ligamenta arcuata externa and 

 interna ; while the fibres passing from all those parts will be traced to their 

 connection with the central tendon ; and the openings for the aorta, oeso- 

 phagus, and vena cava inferior will be examined. The surface of the psoas 

 magnus muscle is next to be cleaned, as well as that of the psoas parvus 

 lying superficial to it (if it be present) (p. 272) ; and, emerging from the 

 fibres of the psoas magnus, the genito-crural nerve will be found and 

 followed downwards. The nerves of the lumbar plexus will be observed 

 principally on the outer and inner aspects of the psoas muscles (p. 660). 

 The fibres of these muscles are to be dissected away from the nerves. In 

 addition to the communicating branches of the plexus, there will be 

 observed, proceeding from the anterior division of the first lumbar nerve, 

 the ilio-hypogastric and ilio-inguinal nerves, often united into one ; from 

 the second lumbar nerve the external cutaneous and genito-crural nerves ; 

 from the second, third, and fourth lumbar nerves together, the anterior 

 crural and the obturator nerves ; and, lastly, the lumbo-sacral cord, formed 

 by the union of a part of the fourth with the whole of the fifth nerve 

 (p. 658). On the bodies of the vertebrae will be found the lumbar part of 

 the chain of sympathetic ganglia ; the branches of communication between 

 which and the spinal nerves are to be dissected (p. 696). 



At this time the dissectors ought to revert to the arrangement of the 

 posterior part of the trans versalis muscle. This they will find to be con- 

 tinued into an aponeurosis which is connected behind with three layers ; of 

 these the most posterior is the fascia lumborum observed in the dissection 

 of the back, the second lies in front of the erector spinse muscle, and the 

 foremost is a much thinner membrane placed in front of the quadratus 



4 A 2 



