998 THE URINARY ORGANS. 



to open into a plexus of efferent lymphatic vessels which are contained in the 

 capsule. 



In the medullary portion the fibrous stroma seems to be collected together 

 into a much closer arrangement, and forms bundles of connective tissue Avhich are 

 loosely applied to the large plexus of veins of which this part of the organ mainly 

 consists. In the interstices lie a number of cells compared by Frey to those of 

 columnar epithelium. They are coarsely granular, do not contain any fat- 

 molecules, and some of them are branched. Luschka has affirmed that these 

 branches are connected with the nerve-fibres of a very intricate plexus which is 

 found in the medulla : this statement has not been verified by other observers, 

 for the tissue of the medullary substance is less easy to make out than that of the 

 cortical, owing to its rapid decomposition. 



The numerous arteries which enter the suprarenal bodies from the sources 

 mentioned below penetrate the cortical part of the gland, where they break up 

 into capillaries in the fibrous septa, and these converge to the very numerous veins 

 of the medullary portion, which are collected together into the suprarenal vein, 

 which usually emerges as a single vessel from the centre of the gland. 



The arteries supplying the suprarenal capsules are numerous and of large 

 size ; they are derived from the aorta, the phrenic, and the renal ; they sub- 

 divide into numerous minute branches previous to entering the substance of the 

 gland. 



The suprarenal vein returns the blood from the medullary venous plexus, and 

 receives several branches from the cortical substance ; it opens on the right side 

 into the inferior vena cava, on the left side into the renal vein. 



The lymphatics terminate in the lumbar glands. 



The nerves are exceedingly numerous, and are derived from the solar and 

 renal plexuses, and, according to Bergmann, form the phrenic and pneumogastric 

 nerves. They enter the lower and inner part of the capsule, traverse the cortex, 

 and terminate round the cells of the medulla. They have numerous small ganglia 

 developed upon them, from which circumstance the organ has been conjectured to 

 have some function in connection with the sympathetic nervous system. 



THE CAVITY OF THE PELVIS. 



The cavity of the pelvis is that part of the general abdominal cavity which is 

 below the level of the linea ilio-pectinea and the promontory of the sacrum. 



Boundaries. It is bounded behind by the sacrum, the coccyx, the Pyriformis 

 muscle, and the great sacro-sciatic ligaments ; in front and at the sides by theossa 

 pubis and ischia, covered by the Obturator muscles ; above, it communicates with 

 the cavity of the abdomen ; and below, the outlet is closed by the triangular 

 ligament, the Levatores ani and Coccygei muscles, and the visceral layer of the 

 pelvic fascia, which is reflected from the wall of the pelvis on to the viscera. 



Contents. The viscera contained in this cavity are the urinary bladder, the 

 rectum, and some of the generative organs peculiar to each sex, and some convo- 

 lutions of the small intestines ; they are partially covered by the peritoneum, 

 and supplied with blood-vessels, lymphatics, and nerves. 



THE BLADDER. 



The bladder is the reservoir for the urine. It is a musculo-membranous sac 

 situated in the pelvis, behind the pubes, and in front of the rectum in the male, 

 the cervix uteri and vagina intervening between it and that intestine in the female. 

 The shape, position, and relations of the bladder are greatly influenced by age, 

 sex, and the degree of distention of the organ. During infancy it is conical in 

 shape, and projects above the upper border of the ossa pubis into the hypogastric 

 region. In the adult, when quite empty and contracted, it is cup-shaped, and on 

 vertical median section its cavity, with the adjacent portion of the urethra, pre- 

 sents a Y-shaped cleft, the stem of the Y corresponding to the urethra. It is 





