Kidney Anatomy and Function

• Urinary System Function: Removes excess water, salts, and protein metabolism products from the blood while maintaining its pH.
• Structures of the urinary system: Kidneys, ureters, urinary bladder, and urethra.

Kidney Location and Features

• Retroperitoneal in location
• Located against the psoas major muscle.
• Span from T12 to L3.
• Dimensions: 11cm x 6cm x 3cm
• Weight: 150g in males, 135g in females.
• Key external features: Superior pole, inferior pole, medial margin, lateral margin, renal hilum, anterior surface, posterior surface.

Kidney Anterior Relations

• Suprarenal area.
• Hepatic area(Right)
• Duodenal area (Right)
• Colic area (Right)
• Splenic area (Left)
• Gastric area (Left)
• Pancreatic area (Left)
• Jejun area (Left)
• Small intestines

Kidney Posterior Relations

• Extends to the eleventh and twelfth ribs.
• Crosses the first lumbar transverse processes.
• Lateral arcuate ligament
• Subcostal vessels and nerve
• Iliohypogastric nerve
• Ilioinguinal nerve

Layers Surrounding the Kidney (From Inside Out)

• Fibrous capsule (superficial and deep layers, the deep layer lines the renal sinus and continues with the walls of the calyces)
• Adipose capsule (perirenal fat)
• Renal fascia
• Pararenal fat (retroperitoneal)

Other Anatomical Considerations

• The kidney is invested by a fibrous renal capsule.
• The renal capsule is embedded in the adipose capsule (perirenal fat).
• The adipose capsule is thicker on the posterior side of the kidney.

Renal Fascia Details

• Encloses the kidney.
• Surrounds the fibrous and adipose capsules and the suprarenal gland.
• It is a continuation of subperitoneal fascia.
• It adheres to the parietal peritoneum.
• The anterior lamina blends medially anterior to the abdominal aorta and inferior vena cava.
• The posterior lamina continues with the fascia of psoas major medially.
• Connects to the transversalis fascia laterally, blending with the prevertebral fascia posteriorly.
• It is continuous with the diaphragmatic fascia superiorly and the iliac fascia inferiorly.

Cortex of the Kidneys

• Cortex is where the urine is filtered through the Bowman's capsule.
• Contains stria medullaris (Ferrein's pyramid = medullary ray).

Medulla of the Kidneys

• Medulla is where urine is collected.
• Contains renal columns which are cortical parts between two Malpighi pyramids.

Renal Sinus Components

• Renal calyces (minor and major)
• Renal pelvis
• Vessels and nerves
• Adipose tissue

Renal Arterial Branching

• Segmental artery
• Interlobar artery
• Arcuate artery
• Interlobular (cortical radiate) artery (includes capsullar branches)
• Afferent glomerular artery
• Capillaries
• Efferent glomerular artery
• Aa recti (from eff glomerular and arcuate arteries)

Renal Lobe

• A cortical lobule (renal lobule) consists of the nephrons grouped around a single medullary ray.
• Drains into a single collecting duct.

Vessels Supplying the Kidney

• Renal artery originates from the abdominal aorta at the level of the intervertebral disc between L1-2.
• Renal arteries and renal fascia hold kidneys in place.

Renal Vein

• Path of urine drainage: Nephron -> Collecting duct -> Minor calyx -> Major calyx -> Renal pelvis -> Ureter -> Urinary bladder

Innervation of the Kidneys

• Renal nerve plexus involves the aorticorenal ganglion, least splanchnic nerve, and vagus nerve.
• Sympathetic constrict the vessels lessens the amount of blood, reducing the amount of filtrated urine.

Upper and Lower Urinary Systems

• Upper: Consists of the renal calyces, the renal pelvis, and the ureter.
• Lower: Urinary bladder and urethra.

Ureters Overview

• Retroperitoneal location.
• Extends between the renal pelvis and bladder
• Length is 25-30 cm.
• Three parts: Abdominal, Pelvic, and Intramural (approximately 2 cm).
• Normal constrictions: At the ureteropelvic junction (beginning), at crossing the pelvic brim andwhere it traverses the bladder wall (intramural part).
• Constricted areas are potential sites of obstruction by ureteric stones (calculi).

Bladder Openings

• Opening of Right ureter
• Opening of Left ureter

Abdominal Part of Ureters

• Between the renal pelvis.
• Terminates at the line where the common iliac vessels cross to enter the pelvis.
• Medially related to the psoas major muscle.
• Anteriorly crossed by the testicular/ovarian artery.
• Right ureter: Relates to the descending part of the duodenum, right colic, and iliocolic vessels.
• Left ureter: Relations include the jejunum and left colic vessels.

Female Ureter

• The ureters are closely related to the ovaries within the pelvis.
• Watch out not to damage the ureters during surgery related to the ovaries.
• The ureters cross the uterine arteries posteriorly about 2 cm superior to the ischial spine.
• This relationship should be a great consideration during hysterectomy when removing both uterus and the uterine arteries.

Male Ureter

• The vas deferens crosses the ureters anteriorly.

Arterial Supply of the Ureters

• Renal artery
• Abdominal aorta
• Testicular (ovarian) artery
• Common iliac artery
• Internal iliac artery
• Superior vesical artery
• Inferior vesical artery (in males)
• Uterine artery (in females)

Veins of the Ureters

• Form a venous network around the ureter.
• Follow the arteries.
• Renal vein
• Inferior vena cava
• Endopelvic vein plexus

Innervation of the Ureters

• Renal plexus, aortic plexus, and superior hypogastric plexuses (T10-L1).
• Pelvic splanchnics (S2-4).