Kidney

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1. KIDNEYS Dr. Vibhash Kumar Vaidya

2. INTRODUCTION Synonyms: Ren : kidney (in Latin); Nephros : kidney (in Greek). The kidneys are two bean-shaped, reddish-brown organs within the abdomen situated on the posterior abdominal wall . They are the major excretory organs. R emove the waste products of protein metabolism and excess of water and salts from the blood. E ssential for maintaining the electrolyte and water balance in the tissue fluids of the body. necessary for survival . Dr. Vibhash

3. LOCATION The kidneys lie on the posterior abdominal wall. O ne on each side of the vertebral column, behind the peritoneum. Opposite 12th thoracic and upper three lumbar (T12–L3) vertebrae . They occupy epigastric, hypochondriac, lumbar and umbilical regions. Dr. Vibhash

4. LOCATION….. The right kidney lies at a slightly lower level than the left one due to the presence of liver on the right side. Their long axes are slightly oblique (being directed downward and laterally) so that their upper ends or poles are nearer to each other than the lower poles. Both kidneys move downward in vertical direction for 2.5 cm during respiration. Transpyloric plane passes through the upper part of the hilum of the right kidney and through the lower part of the hilum of the left kidney . Dr. Vibhash

5. SHAPE AND MEASUREMENTS Shape: Bean shaped. Measurements: Length: 11 cm. (left kidney is slightly longer and narrower). Width: 6 cm. Thickness: 3 cm ( anteroposterior ) . Weight: 150 g in males; 135 g in females . Dr. Vibhash

6. EXTERNAL FEATURES Each kidney presents the following external features: Two poles (superior and inferior). Two surfaces (anterior and posterior). Two borders (medial and lateral). A hilum . Dr. Vibhash

7. POLES :- The superior (upper) pole is thick and round and lies nearer to the median plane than the inferior pole. It is related to the suprarenal gland. The inferior (lower) pole is thin and pointed and lies 2.5 cm above the iliac crest. SURFACES :- The anterior surface is convex and faces anterolaterally. The posterior surface is flat and faces posteromedially. (However , in practice it is difficult to recognize anterior and posterior surfaces. This however is done easily by seeing the relationship of structures present at the hilum.) Dr. Vibhash

8. BORDERS:- The medial border - convex above and below near the poles and concave in the middle. It slopes downward and laterally, and presents a vertical fissure in its middle part called hilum/ hilus which has anterior and posterior lips. The lateral border - convex. HILUM:- The medial border (central part) of the kidney presents a deep vertical slit called hilum. It transmits, from anterior to posterior: Renal vein. Renal artery. Renal pelvis . Dr. Vibhash

9. RELATIONS (Anterior) Anterior surface of Right kidney: Right suprarenal gland. Right lobe of the liver. Second part of the duodenum. Hepatic (right colic) flexure. Jejunum. liver and jejunum are separated from the kidney by peritoneum. Anterior surface of the left kidney: Left suprarenal gland. Spleen. Stomach. Pancreas and splenic vessels. Left colic flexure. Jejunum. stomach, spleen, and jejunum are separated from the kidney by peritoneum. Dr. Vibhash

10. Anterior relations of the kidneys . Dr. Vibhash

11. RELATIONS (Posterior) The posterior relations of two kidneys are the same except that right kidney is related to one rib while left kidney is related to two ribs: Four muscles : Diaphragm, quadratus lumborum , psoas major , and transversus abdominis . Three nerves : Subcostal (T12), iliohypogastric (L1), and ilioinguinal (L1). The subcostal nerve is accompanied by the subcostal vessels. One or two ribs : The right kidney is related to the 12th rib whereas the left kidney is related to the 11th and 12th ribs . Dr. Vibhash

12. Posterior relations of the kidneys Dr. Vibhash

13. CAPSULES (COVERINGS) OF KIDNEY From inwards outwards, the kidney is surrounded by four capsules/coverings as: Fibrous capsule (true capsule). Perirenal (perinephric) fat. Renal fascia (false capsule). Pararenal (paranephric) fat . Dr. Vibhash

14. FIBROUS CAPSULE (TRUE CAPSULE ):- It is a thin membrane which closely invests the kidney. It is formed by the condensation of fibrous connective tissue in the peripheral part of the organ. The capsule passes through the hilum to line the renal sinus and becomes continuous with the walls of calyces where they are attached with the kidney . PERIRENAL (PERINEPHRIC) FAT :- It is a layer of adipose tissue, surrounding the fibrous capsule of the kidney. This fatty capsule is thickest at the borders of kidney and is prolonged through hilum into the renal sinus. In chronic debilitating diseases, the depletion of perinephric fat can and toward the lower pole of the kidney. It fills the paravertebral gutter and forms a cushion for the kidney . Dr. Vibhash

15. RENAL FASCIA (FALSE CAPSULE/ FASCIA OF GEROTA ):- It is a fibroareolar sheath, which surrounds the kidney and perirenal fat. It consists of the following two layers: An ill-defined anterior layer (fascia of Toldt ). A well-defined posterior layer (fascia of Zuckerkandl ). Extensions :- Superiorly - the two layers first enclose the suprarenal gland in a separate compartment and then fuse with each other and become continuous with the diaphragmatic fascia. Inferiorly - the two layers remain separate and enclose the ureter. The anterior layer is gradually lost in the extraperitoneal tissue of iliac fossa while the posterior layer blends with the fascia iliaca . Laterally - the two layers unite firmly and become continuous with the fascia transversalis . Medially - the anterior layer passes in front of the kidney and renal vessels and merges with the connective tissue surrounding the aorta and inferior vena cava (IVC). The posterior layer passes behind the kidney and is attached to fascia covering the quadratus lumborum and psoas major . Dr. Vibhash

16. Capsules (coverings) of the kidney: A, as seen in vertical section through posterior abdominal wall in the lumbar region; B , as seen in cross section through posterior abdominal wall in the lumbar region . Dr. Vibhash

17. PARARENAL (PARANEPHRIC) FAT :- It is a layer of fat lying outside the renal fascia. It consists of considerable quantity of fat being more abundant posteriorly and toward the lower pole of the kidney. It fills the paravertebral gutter and forms a cushion for the kidney . Dr. Vibhash

18. INTERIOR OF KIDNEY When the kidney is split longitudinally, it presents the kidney proper and the renal sinus . Kidney Proper:- The naked eye examination of the kidney proper presents an outer cortex and an inner medulla. The cortex is located just below the renal capsule and extends between the renal pyramids as renal columns (columns of Bertini ). The cortex appears pale yellow with granular texture. The medulla is composed of 5–11 dark conical masses called renal pyramids (pyramids of Malpighi). The apices of renal pyramids form nipple-like projections-the renal papillae which invaginate the minor calyces . Dr. Vibhash

19. Renal Sinus:- It is a cavity of considerable size present within the kidney. It takes up a large part of the interior of the kidney and opens at the medial border of the kidney as hilus . It contains: 1. Greater part of the renal pelvis, major and minor calyces. 2. Renal vessels, lymphatics , and nerves. 3. Fat . The sinus is lined by the continuation of the true capsule of the kidney. Numerous nipple-like elevations (renal papillae ) indent the wall of the sinus. The renal pelvis within the sinus is divided into two or three large branches, called major calyces, which further divides to form 5–11 short branches called minor calyces . Dr. Vibhash

20. ARTERIAL SUPPLY The kidneys are supplied by the renal arteries. Usually there is one renal artery for each kidney--arise directly from the abdominal aorta. A bout 30% individuals accessory renal arteries are also found . Renal artery divides into anterior and posterior divisions. The anterior division supplies apical, upper, middle, and lower segments. P osterior division supplies only posterior segment. The branches supplying the sgements are called segmental arteries . Dr. Vibhash

21. Vascular Segments According to Graves (1954), on the basis of distribution of major branches of the renal artery each kidney is anatomically divided into five vascular segments. Each segment has its own artery and between the segments there is no anastomosis . These segments are as follows: Apical consists of the medial side and the anterior part of the superior pole. Upper includes the remainder of the upper pole and the upper part of the anterior aspect. Middle includes lower part of the anterior aspect and lies between the upper and lower segments. Lower consists of the whole of lower pole. Posterior consists of the whole of posterior aspect of the kidney between the apical and lower segments . The junction between the areas supplied by the anterior and posterior divisions of the renal artery is called Brödel’s line (an important anatomical landmark). It is on the posterior aspect of the kidney at the junction of medial 2/3 and lateral 1/3 . It is a functional avascular plane between the posterior segment medially and the upper and middle segments, hence suitable site for surgical incision to remove the renal stones ( nephrolithotomy ). Dr. Vibhash

22. Dr. Vibhash

23. VENOUS DRAINAGE The venous blood from the kidneys is drained by the renal veins (right and left ). LYMPHATIC DRAINAGE The lymphatics from the kidney drain into the para-aortic lymph nodes at the level of origin of the renal arteries (L2). NERVE SUPPLY Each kidney is supplied by the renal plexus of nerves which reach the kidney along the renal artery. The renal plexus consists of both sympathetic and parasympathetic fibres. The sympathetic fibres are derived from T10–L1 spinal segments. parasympathetic fibres are derived from both vagus nerves. Dr. Vibhash

24. CLINICAL ANATOMY Floating kidney (hypermobility of the kidney): The kidney is kept in position by the perirenal fat and renal fascia . However, each kidney moves up and down with respiration . If the amount of perinephric fat is reduced, the mobility of the kidney becomes excessive (floating kidney) and may reduce the symptoms of the renal colic caused by the kinking of the ureter. A floating kidney can move up and down but not from the side to side within the renal fascia. Renal trauma: kidneys are well protected by the lower ribs, lumbar muscles and vertebral column, still a severe blunt injury of the abdomen may crush the kidney against the last 11th and/or 12th ribs, and the vertebral column . The penetrating injuries are usually caused by stab or gunshot wounds. Since about 25% of the cardiac output passes through the kidneys, the severe renal injury can lead to rapid blood loss. Blood from the ruptured kidney or pus in a perirenal abscess first distends the renal fascia, then trickles downward within the fascial compartment and may reach the pelvis . Dr. Vibhash

25. Transplantation of kidney: It is done in chronic renal failure in selected cases. The donor kidney is placed retroperitoneally in the iliac fossa with hilum parallel to the external iliac vessels. The renal artery is anastomosed end to end to the internal iliac artery and renal vein is anastomosed end to side to the external iliac vein. The ureter is implanted into the urinary bladder ( ureterocystostomy ). Dr. Vibhash

26. Thank You…!!!! Dr. Vibhash