Kidneys, Adrenal Glands & Ureters PDF - Anatomy Study Guide

Urinary System At the end of your study, you should be able to:  Describe the structure of the kidneys, their immediate anatomic relations, and neurovascular supply  Understand the arrangement of perirenal fat, pararenal fat, and renal fascia  Describe the structure of the suprarenal glands a...

Urinary System At the end of your study, you should be able to:  Describe the structure of the kidneys, their immediate anatomic relations, and neurovascular supply  Understand the arrangement of perirenal fat, pararenal fat, and renal fascia  Describe the structure of the suprarenal glands and their neurovascular supply  Describe the course of the ureters, points of constriction along their path, and their neurovascular supply Organs of the Urinary System Upper urinary tract: Kidneys and ureters Lower urinary tract: urinary bladder and the urethra Functions of the Kidneys  Regulation of water balance (osmoregulation).  Regulation of pH (acid-base balance) and inorganic ion balance (sodium, potassium and calcium).  Excretion of metabolic and nitrogenous waste products in urine.  Hormonal function (secretion of erythropoietin, renin– angiotensin system to control blood pressure, secretion of vitamin D active metabolite, calcitriol (1,25 dihydroxycholecalciferol)  Gluconeogenesis (formation of glucose from amino acids and other precursors). Location and External Anatomy of Kidneys  Paired reddish brown bean-shaped organs  Retroperitoneal on the posterior abdominal wall, lateral to the vertebral column  Extend from T12–L3 vertebrae  Measure 12 cm tall, 6 cm wide, 3 cm thick (about the size of a clenched fist), weighs 130-150g  male kidneys slighter larger than female  Right kidney is slightly lower (1.2 cm) than the left owing to the right lobe of the liver.  the left is little longer and narrower than the right  the transpyloric plane passes thru’ superior part of right hilum & inferior part of left hilum  The site for transplanting a kidney is in the iliac fossa of the greater pelvis Location and External Anatomy of Kidneys  Each has two surfaces (anterior and posterior), two borders (lateral convex and medial concave), and two poles (upper and lower).  Moves up and down (about 2 -3 cm) in its fascial compartment (but not from side to side) during respiration  Lies obliquely, its upper pole nearer to the midline than its lower  Only the lower poles are palpable in the normal individual  Long axis parallel with the lateral border of psoas major Location and External Anatomy of Kidneys Surface of foetal kidney is lobulated The costovertebral angle (CVA), formed by the 12th rib and vertebral column, is clinically significant for detecting kidney problems, as tenderness in this area, often assessed by tapping or palpating, can indicate conditions like pyelonephritis or renal stones. Location and External Anatomy of Kidneys  The inferior pole of the right kidney is about a finger’s breadth above the iliac crest  For surgical access, a posterior (flank) approach with an oblique incision is usually favored, made midway between the 12th rib and the iliac crest, extending laterally from the lateral border of the erector spinae.  In percutaneous renal biopsy, the biopsy needle is inserted 2.5 cm below the 12th rib to reach the lower pole of the kidney, with the Surface anatomy of the kidneys and abdominal part of ureters patient holding their breath. Coverings of the Kidneys  enclosed in the following layers of fascia and fat  Fibrous renal capsule (true capsule)  strips readily from the normal kidney surface (torn blood vessels extravasates into the perinephric fat space but adheres firmly to an organ that has been inflamed); lines the renal sinus  Perirenal (perinephric) fat  lies between the fibrous capsule and renal fascia; surrounds the kidney (and suprarenal glands)  Renal fascia (false capsule)  condensation of connective tissue that lies outside the perirenal fat and surrounds the kidney (and adrenal glands), the ureter, the renal vessels  superiorly attached to the fascia of the diaphragm, medially to the aorta and IVC and laterally to the transversalis fascia. There is little to no attachment inferiorly.  Limits the spread of infection or tumours from the kidney Location and External Anatomy of Kidneys Pus arising from infection in the renal parenchyma is usually retained within the perirenal fascia, leading to the formation of a perinephric abscess. The abscess can trickles downward within the fascial compartment and may reach the pelvis. It cannot cross to opposite side because of the fascial septum and midline attachment of the renal fascia.  Pararenal (paranephric) fat  fat external to the renal fascia, is continuous with the extraperitoneal (retroperitoneal) fat Nephroptosis (‘floating kidney’) - downward displacement of the kidney (> 5 cm or abt 2 vertebral bodies); may compress the ureter resulting in hydronephrosis; results from inadequate support from the renal fascia, perirenal fat or abdominal muscles. Suprarenal glands occupy separate compartments in the renal fascia so is undisturbed during excessive mobility of the kidney. Renal Fascia Renal fascia the anterior renal fascia (Gerota fascia) and posterior renal fascia (Zuckerkandl fascia), together comprise the renal fascia Location and External Anatomy of Kidneys  Renal sinus: internal fat-filled cavity lined by the fibrous capsule within the kidney that houses renal pelvis, calyces, blood vessels, lymphatics and nerves  Hilus/hilum: external opening on the concave medial border where structures enter and exit. Transmits ureter, renal vessels, nerves and lymphatics. The renal hilum is the entry into the renal sinus  Renal pelvis: funnel-shaped structure that collects urine from the major calyces and directs it into the ureter; formed by convergence of major calyces.  Total capacity of renal pelvis and calyces is about 8 ml.  Important when injecting radiopaque substance through ureter to outline those spaces Location and External Anatomy of Kidneys Variations in the renal pelvis. (a) buried within the renal parenchyma – pyelolithotomy (surgical removal of kidney stones from the renal pelvis) difficult. (b) protrudes outside (extrarenal) – pyelolithotomy easy Location and External Anatomy of Kidneys  Each kidney consists of an outer cortex and an inner medulla Outer cortex  Outer reddish-brown part,  Some parts project into the medulla between the renal pyramids as renal columns (of Bertin). The renal columns (of Bertin) is considered part of the medulla.  Inner medulla  lighter-coloured inner part,  contains renal pyramids (pyramids of Malpighi).  the apex of the renal pyramid (renal papilla), fits into the cup-shaped minor calyx on which the papillary ducts (10 to 25 openings) open into.  minor calyces unite to form major calyces, and 2 or 3 major calyces, which in turn unite to form the renal pelvis. Hilar relations - anterior to posterior (VAP): Vein, Artery, renal Pelvis/ureter. superior to inferior (AVP): Artery, Vein, renal Pelvis/ureter Internal Gross Anatomy of the Kidneys Anterior Relations of the Kidneys  Right kidney –suprarenal gland, right lobe of the liver, 2nd part of duodenum, hepatic flexure, small intestine  suprarenal, duodenal, and colic areas are devoid of peritoneum 2nd part of duodenum may be opened accidentally in performing a right nephrectomy  Left kidney – suprarenal gland, stomach, spleen, pancreatic body and tail, jejunum, descending colon and/or splenic flexure  suprarenal, pancreatic, and colic areas are devoid of peritoneum Anterior relations of the Kidneys Posterior relations of the Kidneys  Anterosuperiorly — the right adrenal (suprarenal) gland  Posteriorly  costodiaphragmatic recess of pleura, medial and lateral arcuate ligaments,  muscles of the posterior abdominal wall (diaphragm, psoas major, quadratus lumborum, transversus abdominis);  subcostal, iliohypogastric and ilioinguinal nerves, subcostal vessels  11 and 12th ribs (left kidney), 12th ribs (right kidney) Posterior relations of the Kidneys Blood Supply of the Kidney  Filter about 180 L of fluid each day, but only 1-2 L of urine is produced. Receives 20–25% of the resting cardiac output.  90% to 95% of the blood passing through the kidney is in the cortex; 5% to 10% is in the medulla  Renal artery, a lateral branch of abdominal aorta, below origin of SMA, at L2  Renal artery divides into anterior and posterior divisions.  anterior division supplies the apical, upper, middle, and lower segments, while posterior division supplies the posterior segment of the kidney. These branches supplying the segments are called segmental arteries.  The five segmental arteries are important when planning partial nephrectomy. They are all end arteries Organs of the Urinary System Summary of Blood Vessels Supplying the Kidney Blood Supply of the Kidney Avascular line of Brodel Avascular plane of the kidney (line of Brodel)- imaginary avascular line along the lateral and slightly posterior aspect of the kidney, which marks the boundary between the anterior and posterior blood supply; suitable site for both open and endoscopic surgical incision to access the inner kidney, eg. during nephrolithotomy Blood Supply  Each renal vein drains into the IVC  left renal vein passes anterior to the aorta (below the origin of the SMA), and receives the left gonadal, adrenal and lumbar vein.  Is 3x longer than the right, and hence is usually the preferred side for live donor nephrectomy. Nutcracker syndrome?  right renal artery passes behind the IVC. Accessory renal arteries  Accessory arteries occur in about 30% of individuals, usually arise from the abdominal aorta or the main renal artery and enter the kidney at the hilum or at one of its poles.  Aberrant (polar) arteries do not enter the kidney at the hilum.  May compress the pelviureteric junction and cause hydronephrosis  Extrarenal branches include the inferior suprarenal artery, branches to the upper ureter, renal capsule, and perinephric fascia 2/6/2025 28 Kidneys may be malrotated, duplicated, horseshoe or even absent, and retroperitoneal, pelvic or ectopic Clinical correlation  Pelvic kidney  Horseshoe kidney- liable to pelviureteric obstruction, infection and stone formation  Nephrolithiasis/Renal calculus/Renal stone  Percutaneous nephrolithotomy/Nephrolithotripsy  Polycystic kidney disease  Kidney transplantation  Kidney Tumours- Wilm’s tumor, Renal cell carcinoma  Renal artery stenosis  Radiological – nephrogram  intravenous pyelography (IVP) or intravenous urography (IVU)  Renal angiography Suprarenal (adrenal) glands  Yellowish retroperitoneal organs located in the upper pole of the kidneys. The left lies superiomedially, its lower pole above the hilum  Each gland weighs 4–8 g (average 5 g, slightly larger in females), measures approximately 4 × 3 × 1 cm  Located deep to the 10th and 11th ribs, just lateral to either side of the vertebral column. Their position varies with respiration by approx. 3 cm with each movement of the diaphragm  Surrounded by Gerota's fascia, but are separated from the kidneys by the perirenal fat  Right is pyramidal whereas the left is crescent-shaped in shape. Between the two glands is the coeliac plexus  Each gland has a yellow cortex and a dark brown medulla.  Large at birth because of the presence of the fetal cortex Suprarenal glands Anatomical relations of the Suprarenal gland right adrenal gland is in close stomach, pancreas, and spleen lie proximity to the IVC and liver anterior to the left adrenal gland Anatomical relations of the Suprarenal glands Suprarenal glands  As endocrine organs, receives arteries from 3 sources:  superior suprarenal artery from the inferior phrenic artery,  middle suprarenal artery from the abdominal aorta,  inferior suprarenal artery from the renal artery.  suprarenal vein empties into the IVC on the right and the renal vein on the left.  Lymph drainage to lateral aortic nodes  E A F B G H C D I J 2/6/2025 Ureters  Fibromuscular tubes that connect the renal pelvis to the urinary bladder in the pelvis  Retroperitoneal, about 25 to 30 cm  Distinguished from vessels and nerves in living body by its: whitish, non-pulsatile and peristaltic activity when gently pinched with forceps- Kelly's sign  Parts: abdominal, pelvic and intravesical/intramural  The pelvic ureter is enveloped in a fibromuscular sheath (Waldeyer sheath) which aids in fixing the ureter to the bladder  Intravesical ureter passes obliquely through the bladder wall. This prevents reflux of urine during urinary bladder contraction. Ureters  Relations of the right Ureter  Anterior: 2nd part of duodenum, terminal part of the ileum, right colic and ileocolic vessels, gonadal vessels, and the root of the mesentery of the small intestine  Posterior: right psoas muscle, which separates it from the lumbar transverse processes, bifurcation of the right common iliac artery  Relations of the left Ureter  Anterior: sigmoid colon and mesocolon containing sigmoidal arteries, left colic vessels, and gonadal vessels  Posterior: left psoas muscle, which separates it from the lumbar transverse processes, bifurcation of the left common iliac artery.  Medial: Inferior mesenteric vein The ureter in male. Note the structures that crosses it in front Pelvic Ureter  Male: lies above the seminal vesicle near its termination and is crossed superficially by the vas deferens Pelvic Ureter  Female: Passes posterior to the ovary at the ovarian fossa to reach the base of the broad ligament, adjacent to the lateral fornix of the vagina, then crossed by the uterine artery (water under the bridge) before it enters the bladder.  Ureters are at risk of injury during pelvic surgery and hysterectomy. Stones impacted in the lower ureter can be felt during a vaginal examination through the lateral fornices.  Internal iliac artery "yellow water" under "red bridge" Sites of constriction of the ureter  Anatomical constriction Sites of ureter  Pelviureteric junction (PUJ), where the renal pelvis joins the ureter  at the pelvic brim/inlet where the ureter crosses the bifurcation of the common iliac artery  Ureterovesical junction (VUJ) – narrowest of all, where the ureter enters the wall of the urinary bladder  Ureteric calculus are likely to lodge at these narrowing leading to hydroureter and hydronephrosis Normal constrictions of the ureters demonstrated by retrograde pyelogram. Blood Supply  receives blood from all available arteries along its course:  Proximal third: ureteric branches from renal artery  Middle third: abdominal aorta, gonadal, common and internal iliac arteries The abdominal ureter is supplied by vessels originating medial to the ureter. Hence dissection should be approached laterally  Distal third: superior & inferior vesical, uterine arteries. Pelvic ureter is supplied by vessels lateral to the ureter. Hence dissection should be approached medially Blood Supply and Lymph drainage  Vessels anastomose in the adventitia of the ureter forming longitudinal channels  ureter can be safely transected at any level intraoperatively, and a uretero-ureterostomy performed, without compromising its viability  Venous drainage follows arterial supply. the renal fascia covers the ureter, so stripping off this fascia, while mobilizing the ureter for transplantation, will hamper the blood supply of the ureter and may cause its necrosis  Lymphatic drainage  upper abdominal ureter to lateral aortic (para-aortic) nodes  lower abdominal ureter to common iliac nodes,  pelvic ureter to common, external or internal iliac nodes Ureters On plain x-ray, the ureter lies along the tips of the transverse processes of lumbar vertebrae, crosses in front of the sacro-iliac joint, swings out to the ischial spine and then passes medially to the bladder. IVU or IVP? Hydronephrosis and hydroureter of the right Note the congenital abnormality kidney found in the radiograph Renal Stone Disease (Nephrolithiasis) 75% calcium salts (oxalate or phosphate), 15% magnesium ammonium phosphate, 10% uric acid or cysteine that develops in the urinary tract. Risk factors: high urine calcium levels, obesity, certain foods, some medications, calcium supplements, hyperparathyroidism, gout and not drinking enough fluids, heredity, associated diseases (sarcoidosis, inflammatory bowel disease, cancer), inborn errors of metabolism (such as hereditary cystinuria) and hyperparathyroidism, which leads to increased excretion of calcium salts. Stones are classified by their location: nephrolithiasis (in the kidney), ureterolithiasis (in the ureter), cystolithiasis (in the bladder), or by what they are made of (calcium oxalate, uric acid etc). Can be corrected by either surgical removal of the stone (percutaneous nephrolithotomy) or its disintegration using focused ultrasonic shock waves in a procedure called lithotripsy. Randall's plaques are calcium phosphate deposits that form in the papillary interstitium of the kidneys and are believed to act as the starting point or precursor for the development of kidney stones. Innervation of the kidneys and suprarenal glands  The nerves of the kidneys and suprarenal glands arise from the renal and celiac plexuses, abdominopelvic splanchnic nerves (lesser and least), and the aorticorenal ganglion  Sympathetic preganglionic fibers from T10–L1 (via the lesser and least splanchnic nerves) travel to the renal and celiac plexuses, synapsing in the aorticorenal ganglion, where postganglionic fibers chiefly mediate vasoconstriction of renal blood vessels and stimulate renin secretion from juxtaglomerular (GC) cells.  Preganglionic parasympathetic fibers enter the renal plexus via the vagus nerve. Some afferent fibers travel with vagal fibers, and primarily involved in reflex functions like nausea and vomiting due to the vagus nerve's connection to the gastrointestinal system  Renal pain, caused by stretching of the renal capsule due to inflammation (e.g., glomerulonephritis) or obstruction at the pelvi-ureteric junction, is felt in the lower back and flanks (T12 and L1 nerve distribution), and may radiate to the anterior abdominal wall and external genitalia Innervation of the suprarenal glands  Preganglionic sympathetic fibres from the thoracic splanchnic nerves, especially the greater splanchnic, pass through the sympathetic chain and celiac ganglion without synapsing and terminate directly on the chromaffin cells of adrenal medulla to release epinephrine and norepinephrine. The medulla of the suprarenal gland lacks parasympathetic innervation Autonomic innervation of the kidney and suprarenal gland. 2/6/2025 57 Innervation of the ureters  Nerve supply is primarily derived from the renal, aortic, superior hypogastric, and inferior hypogastric plexuses.  Sympathetic Innervation: originates from T10–L2 spinal segments. Fibers travel via the renal, aortic, and hypogastric plexuses.  Parasympathetic Innervation  Upper ureter: Supplied by the vagus nerve (CN X).  Lower ureter: Receives fibers from S2–S4 (pelvic splanchnic nerves).  Peristalsis is generated by intrinsic pacemaker cells in the renal pelvis and minor calyces. Exact role of autonomic innervation is unclear Innervation of the ureters  Sensory (afferent) innervation. Pain fibers follow sympathetic pathways back to T10–L2, leading to referred pain in the flank, lower abdomen, groin, and genital region (dermatomes T11–L2)  In ureteric colic (severe intermittent pain due to contraction of ureteric smooth muscle to overcome an obstruction), pain follows the T11–L2 dermatomes, radiating from the loin to the groin, scrotum/labia majora, testis, or tip of the penis, and may extend to the front of the thigh via the femoral branch of the genitofemoral nerve (L1–L2).