Kidney and Ureter Anatomy

• The presentation covers the anatomy of the kidney and ureter.
• The learning outcomes include describing anatomy, discussing urinary calculi, identifying structures on radiological imaging, and understanding congenital abnormalities.

Posterior Abdominal Wall

• The posterior abdominal wall consists of osteology (five lumbar vertebrae, sacrum, pelvic bones, and ribs 11-12) and muscles (psoas major and minor, quadratus lumborum, and iliacus).
• The hilum of the kidneys is located at the L1 vertebral level.

Transpyloric Plane

• The transpyloric plane passes through L1, halfway between the suprasternal notch and symphysis pubis, or the xiphoid process and umbilicus.
• At the L1 level, the linea semilunaris cuts the costal margin at the 9th costal cartilage.
• Other features at this level include the fundus of the gallbladder, pylorus of the stomach, first part of the duodenum, neck of the pancreas, portal vein formation, superior mesenteric artery origin, hila of kidneys (left higher than right), and hilum of the spleen.

Nerves of the Posterior Abdominal Wall

• Formed from the anterior rami of L1-3 (L4), with a contribution from T12, the lumbar plexus innervates.
• Lateral to the psoas are the subcostal (T12), ilio-hypogastric (L1), ilio-inguinal (L1), lateral cutaneous nerve of the thigh (L2-3), and femoral (L2-4) nerves.
• Medial to the psoas are the obturator (L2-4) and lumbosacral trunk (L4-5) nerves.
• The genitofemoral nerve (L1-2) passes through the psoas.

Surface Anatomy and Position of Kidneys

• The kidneys have a bean shape and are retroperitoneal in the posterior abdominal region, lateral to the vertebral column.
• They extend from approximately the T12 vertebra to the L3 vertebra.
• The right kidney is typically lower than the left. Located around the L1 vertebra, the hilum of each kidney serves as a point of entry.

Anterior Relations of Kidneys

• The right kidney is anteriorly related to the right adrenal gland, liver, peritoneum, right colic flexure, and duodenum.
• The left kidney is anteriorly related to the left adrenal gland, stomach, spleen, pancreas, left colic flexure, and descending colon.

Posterior Relations of Kidneys

• The kidneys are posteriorly related to the psoas, quadratus lumborum, and transversus abdominis muscles.
• The left kidney is related to the 11th and 12th ribs; the right kidney is related to the 12th rib.
• The subcostal vessels and nerves, along with the iliohypogastric and ilioinguinal nerves, run behind the kidneys.

Diaphragm

• It lies posterior to the superior pole of the kidneys.
• The pleural sacs & costodiaphragmatic recesses extend posterior to the kidneys.
• Biopsies in this area must be approached with caution, as it can cause pneumothorax.

Fascia Around the Kidney

• The renal capsule adheres to the kidney surface, preventing infections from spreading.
• The adipose capsule cushions the kidney and helps attach it to the body wall, including the perinephric and paranephric fat layers.
• The renal Gerota's fascia is dense and fibrous, anchoring the kidney and determining stage of renal cancer.
• Suprarenal glands are enclosed in the fascial compartment, separated by a thin septum.

Internal Anatomy of the Kidney

• The renal cortex is a band of pale tissue that surrounds the renal medulla, extending between pyramids and forming renal columns.
• The renal medulla is the inner portion, divided into triangular-shaped renal pyramids with outward-directed bases and inward-projecting apices.
• The apical projection (renal papilla) contains the openings of the papillary ducts and is a surrounded by a minor calyx.
• The minor calyx receives urine from the papillary ducts.
• The major calices are formed by the unification of several minor calices.
• The renal pelvis is the funnel-shaped superior end of the ureters formed by the unification of 2-3 major calices.

Hilum of the Kidney

• The hilum is a deep vertical slit on the medial margin of each kidney.
• It is the entry and exit point for renal vessels, lymphatics, and nerves.
• In the hilum, the vein is anterior, the artery is middle, and the ureter is posterior.
• Renal arteries arise from L1-L2 level.
• The left renal artery usually arises slightly higher, and the right renal artery is longer, passing posterior to the inferior vena cava (IVC).
• The left renal vein is longer and passes between the abdominal aorta and the superior mesenteric artery (SMA).

Renal Arteries

• Each renal artery separates into an anterior and posterior branch.
• The branches are end arteries.
• There are no anastomoses present.
• Blockage or trauma to any arterial branch may cause ischemia and necrosis of the renal parenchyma.

Ureters

• Muscular tubes transport urine from the kidneys to the bladder.
• Arising from the renal pelvis, the ureters carry urine from the renal pelvis to the bladder.
• Descending inferiorly and medially (~30cm).
• As it passes inferiority, the renal pelvis narrows through the hilum and becomes continuous with the ureter at the ureteropelvic junction.
• The ureters descend retroperitoneally on the medial aspect of the psoas major muscle and along the tips of the transverse processes of the L1-L5 vertebrae.
• At the pelvic brim, the ureters cross either the end of the common iliac artery or the beginning of the external iliac artery and enter the pelvic cavity.
• They enter the bladder at the level of the ischial spine.
• In males, the ureter is crossed by the vas deferens; in females, it is crossed by the uterine artery.

Ureter Constrictions

• Located at the ureteropelvic junction.
• Where the ureters cross the pelvic brim.
• Where the ureters enter the wall of the bladder.

Ureter Blood Supply, Histology, and Innervation

• The blood supply comes from renal, gonadal, common iliac, and the internal iliac arteries and its branches, and the abdominal aorta.
• Histologically, the ureters consist of transitional epithelium (waterproof and distensible).
• Renal, aortic, superior hypogastric, and inferior hypogastric plexuses innervate (nerves follow the blood supply).
• Visceral efferents have both sympathetic and parasympathetic components.
• Visceral afferents return to the T11 to L2 spinal cord level, referring pain to corresponding cutaneous areas ("loin to groin" pain).

Ureteric Calculi

• Tips of L1-L5 processes and sacroiliac joint on X-Rays can identify ureters.
• Kidney stones (Urinary calculi): vast majority are composed of Calcium Oxalate +/- Phosphate and can been seen using X-Rays.

Vesico-Ureteric Reflux

• Retrograde flow of urine from the bladder to the ureter or kidney.
• Primary VUR is congenital, where the intramural region of ureter is too short to cause a valve effect.
• Secondary VUR is often due to states of high pressure voiding, such as with posterior urethral valves, neuropathic bladder, or through a duplex collecting system.
• Recurrent UTIs are often associated

Hydronephrosis

• Hydronephrosis is the distention and dilatation of the renal pelvis and calyces.
• Caused by an aberrant artery crossing over the ureteropelvic junction, stone, enlarged prostate, pregnancy or cancer of the cervix.

Bifid Collecting System

• This term refers to complexity to upper pole obstruction, calculi and reflux disease.
• Weigert-Meyer Rule: In complete duplex collecting systems, duplicated ureters insert separately into the bladder where the upper pole ureter is the ectopic ureter and its orifice inserts inferomedially to the lower pole normal ureter.

Kidney Defects

• These include pelvic kidney and horseshoe kidney, and duplex collecting ducts.

Adrenal Glands

• They lie immediately superior and anterior to the superior pole of each kidney, but are functionally unrelated.
• These glands are surrounded by perinephric fat and enclosed by renal fascia.
• The outer cortex which is regulated by the Pituitary, Hypothalamus and Renin-Angiotensin Axis
• Clinical manifestations when there is an issue with the Cortex, could cause Cushing's Syndrome; Conn's Disease; Addison's Disease
• The medulla contains chromaffin cells to produce adrenaline and noradrenaline (catecholamines); clinical conditions tied tot he medulla include Phaeochromocytoma or Waterhouse Friderichsen

Adrenal Gland Relations

• For the left adrenal gland, it is medially related to the Coeliac trunk and left crus of diaphragm, laterally the medial kidney aspect and upper pole and renal hilum, anteriorly related to the lesser sac and stomach and posteriorly related to the diaphragm.
• For the right adrenal gland, it is medially related to the inferior vena cava, laterally related to the upper renal pole, anteriorly related to the bare area of the liver, and posteriorly related to the diaphragm.

Adrenal Gland Blood Supply & Venous Drainage

• Includes the Superior suprarenal arteries via inferior phrenic artery, middle suprarenal artery via abdominal aorta and Inferior suprarenal arteries via renal artery.

Lymphatic Drainage

• The abdominal aorta and the cisterna chyli drain into the lymphatic system to remove unwanted products.
• Kidney waste drains to lumbar nodes near the origin of the renal artery, upper ureter drains to lumbar nodes, the middle ureter drains to common iliac nodes and the Inferior ureter drains to external and internal iliac nodes