748 A MANUAL OF ANATOMY 



inferior vena cava, whilst that of the left is situated fully 

 I inch from the aorta. This border is concave, and presents 

 a longitudinal fissure, called the hilum, which extends over about 

 its middle third. It presents two somewhat thick lips, anterior 

 and posterior, and it leads to a cavity within the organ, called the 

 sinus. It transmits the following structures in order from before 

 backwards : the branches of the renal vein, the branches of the 

 renal artery, with branches of the renal sympathetic plexus and 

 lymphatics, and the pelvis of the kidney. 



The side to which a kidney belongs may be ascertained in the 

 following way : if the organ is held with that end dowTiwards towards 

 which the ureter is naturally inclined, and that surface backwards 

 which coincides with the pelvis at the hilum, the convex border will 

 then indicate the side to which the organ belongs. 



Varieties — Form. — The kidneys may be much elongated, or somewhat 

 round, or triangular. The lobulated condition, which is characteristic of the 

 kidney in early life, may persist in the adult. 



Size. — One kidney may be diminished in size, in which cases there is a 

 proportionate increase in the other organ. 



Position. — It is very rare to find the kidneys higher than usual, but one or 

 both not infrequently extend into the iliac fossa, or over the pelvic brim. 



Number — Diminution. — One kidney (usually the left) may be entirely 

 suppressed, in which cases the solitary kidney usually occupies its normal 

 position, and may, or may not, be of large size. Increase. — The number 

 may be increased to three, the additional organ being lateral, or median, in 

 position. 



Horseshoe Kidney. — This condition is brought about by the fusion of the 

 lower parts of the organs, the connecting band of renal substance extending 

 across the vertebral column. 



Preternatural Mobility. — The kidney is usually anchored in its normal 

 position by its capsule and the adjacent viscera, but it is sometimes movable, 

 which may be due to one of two causes : (i) the capsule may be very loose, 

 giving rise to the condition known as movable kidney ; or (2) the organ may 

 be attached to the posterior abdominal wall by a peritoneal fold, called the 

 meso-nephron, in which case the condition known as floating kidney occurs, 

 this being said to be more frequent on the right side. 



For the structure and development of the kidney, see Index. 



Ureter.- — The ureter is the excretory duct of the kidney, and it 

 conveys the urine to the bladder. It is a cylindrical, thick-walled 

 tube, like a goose-quill, its average length being about 12 inches, 

 and its diameter about ^ inch. The ureter proper commences, 

 towards the lower end of the kidney, where it is the continuation of 

 the pelvis, and it terminates in the bladder. The pelvis is funnel- 

 shaped and flattened from before backwards. It lies partly in the 

 sinus, where it receives the calices, and partly outside the hilum, 

 where it lies behind the other transmitted structures. Its direc- 

 tion is downwards and inwards, and, having become narrow, it 

 passes into the ureter proper towards the lower end of the kidney. 



The ureter proper passes downwards and inwards behind tht 

 peritoneum, in contact with the posterior abdominal wall. T 

 rests at first upon the psoas magnus and its sheath, being hen 

 crossed superficially by the spermatic (or ovarian) vessels, whici 



