Kidneys Location & Description
The waste products leave the kidneys as urine which passes down the ureters to the urinary bladder which is located within the pelvis. The urine leaves the body in the urethra. The kidneys are reddish brown and lie behind the peritoneum high up on the posterior abdominal wall on either side of the vertebral column. They are largely under cover of the costal margin. The right kidney lies slightly lower than the left kidney because the large size of the right lobe of the liver. With contraction of the diaphragm during respiration, both kidneys move downward in a vertical direction by as much as 1 inch (2.5 cm ) . On the medial concave border of each kidney is a vertical slit that is bounded by thick lips of the renal substance and is called the hilum. The hilum extends into a large cavity called the renal sinus. The hilum transmits from front backward: The renal vein; two branches of the renal artery; ureter; the 3rd branch of the renal artery ( V.A.U.A. ) ; lymph vessels and sympathetic fibers . 1 2 3 &sinus Covering: Fibrous capsule: It surrounds the kidney and is closely applied to its outer surface. Perirenal fat: It covers the fibrous capsule. Renal fascia: It is a condensation of connective tissue that lies outside the perirenal fat and enclose the kidneys and suprarenal glands. It is continuous laterally with the fascia transversalis. Pararenal fat: It lies external to the renal fascia. It is in a large quantity. It forms part of the retroperitoneal fat. N. B.2 & 3 and 4 support the kidneys and hold them in position on the posterior abdominal wall. Renal Structure Each kidney has a dark brown outer cortex and a light brown inner medulla The medulla is composed of about a dozen ( 12 ) renal pyramids, each having its base oriented toward the cortex and its apex ( renal papilla ) projecting medially. The cortex extends into the medulla between adjacent pyramids as the renal columns. Extending from the bases of the renal pyramids into the cortex are striation(medullary rays ). The renal sinus is the space within the hilum. It contains the upper expanded end of the ureter ( renal pelvis ) which divided into 2 or 3 major calyces, each of which divides into 2 or 3 minor calyces. Each minor calyx is indented by the apex of the renal pyramid ( renal papilla). Anterior Relations of the Right Kidney
The suprarenal gland; liver; second part of the duodenum; right colic flexure and coils of small intestine. Anterior Relation of the left Kidney The suprarenal gland; spleen; stomach; pancreas; left colic flexure and coils of the jejunum. N.B. many of the structures are directly in contact with the kidneys, whereas other are separated by visceral layers of peritoneum. Posterior Relation of the Right Kidney
The diaphragm; costodiaphragmatic recess of the pleura; 12th rib; psoas; quadratus lumborum; transversus abdominis muscles; subcostal (T 12 ); iliohypogastric and ilioinguinal nerves ( L1 ). Posterior Relation of the Left Kidney As the right except that it lies higher than the right. So, it is related to 11th and 12th ribs. N.B. the right kidney lies at a slightly lower level than the left kidney and the lower pole may be palpated in the right lumbar region at the end of deep inspiration in a person with poorly developed abdominal musculature. Arteries The renal artery arises from the aorta at the level of the 2nd lumbar vertebra. Each renal artery usually divides into 5 segmental arteries that enter the hilum of the kidney, 4 in front and one behind the renal artery. Lobar arteries arise from each segmental artery one for each renal pyramid. Before entering the renal substance each lobar artery gives off 2 or 3 interlobar arteries. The interlobar arteries run toward the cortex on each side of the renal pyramid. At the junction of the cortex and medulla, the interlobar arteries give off the arcuate arteries which arch over the bases of the pyramids. The arcuate arteries give off several interlobular arteries that ascend in the cortex. The afferent glomerular arterioles arise as branches of the interlobular arteries. Veins Clinical Notes Renal Pain
The renal vein emerges from the hilum in front of the renal artery and drains into the inferior vena cava. Lymph Drainage Lateral aortic lymph nodes ( para- aortic ) around the origin of the renal artery. Nerve Supply Renal sympathetic plexus. The afferent fibers that travel through the renal plexus enter the spinal cord in the 10th ; 11th and 12th thoracic nerves. Clinical Notes Renal Pain It varies from a dull ( not sharp ) ache to a severe pain in the flank that may radiate downward into the lower abdomen. It can result from stretching of the kidney capsule or spasm of the smooth muscle in the renal pelvis. The afferent nerve fibers pass through the renal plexus around the renal artery and ascend to the spinal cord through the lowest splanchnic nerve in the thorax and the sympathetic trunk. They enter the spinal cord at the level of T12 . Pain is commonly referred along the distribution of the subcostal nerve ( 12 ) to the flank and the anterior abdominal wall. Renal Mobility The kidney are maintained in their normal position by intra- abdominal pressure and by their connections with the perirenal fat ; renal fascia and pararenal fat . Each kidney moves slightly with respiration. If the amount of the perirenal fat be reduced , the mobility of the kidney may become excessive and produce symptoms of renal colic caused by kinking of the ureter. Excessive mobility of the kidney leaves the suprarenal gland undisturbed because both kidney and suprarenal are enclosed within a separate compartment in the renal fascia. Also, any of them can separate easily during operations. Kidney Trauma The kidney are well protected by the lower ribs; lumbar muscles and vertebral column. However, a severe blunt applied to abdomen may crush the right kidney against the last rib & the left kidney against the last 2 ribs and vertebral column. Because 25 % of the cardiac outflow passes through the kidneys, renal injury can result in rapid blood loss. The lower pole of the right kidney can be palpated in the right lumbar region at the end of deep inspiration in a person with poorly developed abdominal muscles. The normal left kidney which is higher than the right is not palpable. Surface Anatomy: On the anterior abdominal wall the hilum of each kidney lies on the transpyloric plane, about 3 fingerbreadths from the midline. On the back, the kidneys extend from the 12 thoracic spine to the 3rd lumbar spine. The hili are opposite the spine of the 1st lumbar vertebra. Draw oblique line, so that: Its upper end is 2.5 cm lateral to the median plane. Its center is 5 cm lateral to median plane. Its lower end is 7.5 cm lateral to the median plane. Ureter The 2 ureters are muscular tubes that extend from the kidneys to the posterior surface of the urinary bladder. The urine is propelled along the ureter by peristaltic contractions of the muscle coat which are assisted by the filtration pressure of the glomeruli. Each ureter measures about 10 inch ( 25 cm ) long. It has 3 constrictions along its course: Where the renal pelvis joins the ureter Where it is kinked as it crosses the pelvic brim. Where it pierces the bladder wall. The renal pelvis is a funnel- shaped expanded upper end of the ureter. It lies within the hilum of the kidney and receives the major calyces Itemerges from the hilum of the kidney and runs vertically downward behind the parietal peritoneum which is adherent to it on the psoas muscle which separates it from the tips of the transverse processes of the lumbar vertebrae. It enters the pelvis by crossing the bifurcation of the common iliac artery in front of the sacroiliac joint. Posterior Relations of the Right Ureter
The ureter then runs down the lateral wall of the pelvis to the region of the ischial spine and turns forward to enter the lateral angle of the urinary bladder. Posterior Relations of the Right Ureter Right psoas muscle which separates it from the lumbar transverse processes. The bifurcation of the right common iliac artery. Posterior Relations of the Left Ureter Left psoas muscle and the bifurcation of the left common iliac artery. Anterior Relation of the Right ureter
The 2nd part of the duodenum; terminal part of the ileum; right colic and ileocolic vessels; right testicular or ovarian vessels and the root of the mesentery of the small intestine. Anterior Relation of the Left ureter The sigmoid colon; sigmoid mesocolon; left colic vessels and the left testicular or ovarian vessels. N.B. The inferior mesenteric vein lies along the medial side of the left ureter. Arteries Veins Lymph Drainage Nerve Supply
The upper end is supplied by the renal artery The middle portion is supplied by the testicular or ovarian artery. The pelvic part is supplied by the superior vesical artery. Veins Venous blood drains into the corresponding veins. Lymph Drainage The lymph drains into the lateral aortic nodes and the iliac nodes. Nerve Supply Renal; gonadal in the abdomen and hypogastric plexuses in the pelvis. Afferent fibers travel with the sympathetic nerves and enter the spinal cord in the 1st & 2nd lumbar segments Clinical Notes Ureteric Stones Renal Colic
There are 3 sites of anatomic narrowing of the ureter where stones may be arrested. Most stones, although radiopaque, are small enough to be impossible to see definitely along the course of the ureter on plane radiographic examination. An intravenous pyelogram is usually necessary. The ureter runs down in front of the tips of the transverse processes of the lumbar vertebrae, crosses the region of the sacroiliac joint, swings out to the ischial spine and then turns medially to the bladder. Renal Colic The renal pelvis and ureter send their afferent nerves into the spinal cord at segments T11 and 12 and L1 and 2. In renal colic, strong peristaltic waves of contraction pass down the ureter in an attempt to pass the stone onward. The spasm of the smooth muscle causes an agonizing colicky pain which is referred to the skin areas that are supplied by these segments of the spinal cord ( flank; loin and groin ). When a stone enters the low part of the ureter, the pain is felt at a lower level and is often referred to the testis or the tip of the penis in the male and labium majus in the female. Sometimes ureteral pain is referred along the femoral branch of the genitofemoral nerve ( L1 and 2 ) to the front of the thigh . The pain is often so severe that afferent pain impulses spread within the central nervous system giving rise to nausea. Suprarenal gland They are yellowish; ductless and retroperitonealglands. They lie on the upper poles of the kidneys. They are surrounded by renal fascia, but are separated from the kidneys by the perirenal fat. Each gland has yellow cortex and a dark brown medulla. The cortex of the glands secretes hormones that include mineral corticoids which are concerned with the control of fluid and electrolyte balance. Glucocorticoids which are concerned with the control of the metabolism of carbohydrates; fat; and proteins and small amounts of sex hormones which probably play a role in the prepubertal development of the sex organs. The medulla of the suprarenal glands secretes the catecholamines epinephrine and norepinephrine. The right suprarenal gland:
It is pyramidal shaped and caps the upper pole of the right kidney. It lies behind the right lobe of the liver and extends medially behind the inferior vena cava. It rests posteriorly on the diaphragm. The left suprarenal gland: It is crescentic in shape and extends along the medial border of the left kidney from the upper pole to the hilus. It lies behind the pancreas; lesser sac and stomach and rests posteriorly on the diaphragm. Arteries Veins Lymph Drainage Nerve Supply
They are inferior phrenic artery; aorta and renal artery. Veins A single vein emerges from the hilum of each and drains into the inferior vena cava on the right and into the renal vein on the left. Lymph Drainage The lymph drains into the lateral ( para ) aortic nodes. Nerve Supply Preganglionic sympathetic fibers derived from the splanchnic nerves supply the glands. Most of the nerves end in the medulla of the gland.