URINARY SYSTEM KIDNEYS AND URETERS Dr Rania Gabr

1- Describe the normal site, size, shape and position of the kidney 2- Delineate the surface anatomy of the kidney 3- Describe the facsia surrounding the kidney 4- Describe the blood supply of the kidney 5- Describe the beginning termination, and parts of the ureter 6- Discuss the normal sites of ureteric constrictions OBJECTIVES

Organs of the Urinary System

Organs of the Urinary system Kidneys Ureters Urinary bladder Urethra

Kidneys

Location and External Anatomy of Kidneys Bean shaped organs Located retroperitoneally They are largely under cover of the costal margin Lateral to T12–L3 vertebrae R kidney lower than L (due to R lobe of liver) kidney levels change during respiration and postural changes Average kidney 12 cm tall, 6 cm wide, 3 cm thick tilted: superior poles are closer to midline than inferior

Hilum Medial border has a hilum The hilum extends into a large cavity called the renal sinus. The hilum transmits the : from the front backward (V.A.U.A.) 1-renal vein, 2-two branches of renal artery, 3-ureter, and 4-the third branch of renal artery .

Renal fascia and fat From inward to outward 1- Fibrous capsule: It is adherent to the kidney. 2- Perirenal fat : It covers the fibrous capsule 3- Renal fascia: it encloses the kidneys and suprarenal glands. 4- Pararenal fat : it lies external to the renal fascia, and forms part of the retroperitoneal fat. N.B. The last 3 structures support the kidney in position.

Posterior relations 1- Diaphragm, (last intercostal space) 2- Costodiaphragmatic pleural recess. 3- Twelfth rib, 4- Psoas major muscle, 5- Quadratus lamborum m., 6- Transversus abdominis m., Subcostal nerve (T12), Iliohypogastric (L1) nerve. Ilioinguinal (L1) nerve ( Last rib + 4muscles + 3 nerves) NB. The left kidney reaches up to the 11th rib.

Anterior relations Right Kidney : 1- Right suprarenal gland 2- Liver, 3- Second part of the duodenum 4- Right colic flexure 5- Coils of small intestine Left Kidney : 1- Left suprarenal gland, 2- Stomach, 3- Spleen, 4- Pancreas, 5- Left colic flexure, 6- Descending colon 7- Coils of jejunum

Internal anatomy outer cortex: pale, inner medulla 6-18 conical renal pyramids apex - renal papilla projects into the renal sinus renal columns extensions from cortex inward to renal sinus between adjacent renal pyramids

ureter enters the renal sinus, it expands to form a chamber called - renal pelvis pelvis branches to form 2-3 major calyces branch further to form 6-8 minor calyces Each minor calyx surrounds the papilla of a renal pyramid ducts within papilla connect to wall of the calyx and discharge urine produced in the cortex and medulla Urine passes through the calyces into the ureter

Blood Supply Single renal artery arises just inferior to the origin of the superior mesenteric artery between vertebrae LI and LII The left renal artery usually arises a little higher than the right, and the right renal artery is longer and passes posterior to the inferior vena cava.

Multiple renal veins contribute to the formation of the left and right renal veins, both of which are anterior to the renal arteries Importantly, the longer left renal vein crosses the midline anterior to the abdominal aorta and posterior to the superior mesenteric artery and can be compressed by an aneurysm in either of these two vessels.

Arterial supply of the kidney The renal artery arises from the aorta at the level of the second lumbar vertebra. Each renal artery divides into five segmental arteries that enter the hilum of the kidney, four in front and one behind the renal pelvis. They are distributed to different segments of the kidney.

Branches of Segmental arteries 1. Interlobar arteries - pass through renal columns and reach junction between medulla and cortex. It gives the : 2. Arcuate arteries run parallel with the base of the pyramids. It gives the : 3. Interlobular arteries move up into the cortex and branch to form the afferent arteriole

Nephron Each Nephron is associated with two capillary beds: The glomerulus and The peritubular capillary bed. The glomerulus is both fed and drained by arterioles. The afferent arteriole, which arises from an interlobular artery, is the "feeder vessel," and the efferent arteriole receives blood that has passed through the glomerulus. The peritubular capillaries unite to form the interlobular veins, arcuate vein, interlobar vein, renal vein The Renal Vein exits at hilus and joins the IVC Functional unit of the kidney, 1 million nephrons per kidney!

Vascular components of nephron Made up of blood vessels: 1. Glomerulus - network of capillaries within Bowman’s capsule 2. Afferent arteriole - leading into glomerulus 3. Efferent arteriole - leading out of glomerulus 4. Peritubular capillaries - surrounding tubules 5. Vasa recta - specialised loops of blood vessels around long Loop of Henle (juxtamedullary nephrons) Nephrons: 85% are cortical, 15% are juxtamedullary

Tubular components of nephron Glomerular (Bowman’s) capsule – Proximal convoluted tubule – Loop of Henle - hair-pin loop thin descending limb, thick ascending limb 4. Distal convoluted tubule - last section

Venous drainage Both renal veins drain to the inferior vena cava. The left is three times longer than the right (7.5 cm and 2.5 cm). Lymph Drainage: Lateral aortic lymph nodes 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.

Ureters

Ureters Definition: It is a muscular tube transporting urine from kidney to urinary bladder. Length: 20-30 cm long Beginning: It begins as a continuation of renal pelvis.

COURSE IN ABDOMEN: It descends anterior to psoas major muscle (opposite the tips of lumbar transverse processes). It passes over the pelvic brim , crosses the end (bifurcation) of common iliac artery to enter the pelvis. Pyelogram (colour-enhanced)

COURSE IN PELVIS & TERMINATION: It runs downward & backward to the level of ischial spine. It curves forward to open in upper lateral angles of the base of urinary bladder. It runs obliquely for ¾ inch in wall of bladder before opening (valve-like part).

Sites of constriction of the ureters: 1- At the origin: junction of the ureter and the renal pelvis (Ureteropelvic junction) 2- Where the ureters cross the common iliac arteries at the pelvic brim 3- During their entery through the wall of the urinary bladder: Vesiciureteric junction Stones become lodged in these sites

PARTS: 1- Abdominal 2- Pelvic 3- Intramural ARTERIAL SUPPLY: Renal artery Gonadal artery Common iliac artery Internal iliac artery

Nerve supply From: 1- Renal plexus 2- Aortic plexus 3- Superior hypogastric plexus 4- Inferior hypogasrtic plexus Through nerves that follow the blood vessels

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