ANATOMY OF THE ANATOMY OF THE KIDNEYS, BLADDER, KIDNEYS, BLADDER,

URETERS AND URETERS AND URETHRAURETHRA

Dr. E. T. AgidaDr. E. T. Agida MBBS(IB), FWACS, MPA.MBBS(IB), FWACS, MPA.

Chief Consultant Obstetrician and Gynaecologist,Chief Consultant Obstetrician and Gynaecologist,University of Abuja Teaching Hospital.University of Abuja Teaching Hospital.

IntroductionIntroduction

These structures form the urinary These structures form the urinary system.system.

Kidneys-excrete urine Kidneys-excrete urine Ureters-convey urine from the Ureters-convey urine from the

kidneys to the bladderkidneys to the bladder Urinary bladder-Stores urine Urinary bladder-Stores urine

temporarytemporary Urethra-Carries urine from the Urethra-Carries urine from the

bladder to the exterior.bladder to the exterior.

KidneysKidneysDevelopment:Development: Pronephroi (singular pronephros)-Pronephroi (singular pronephros)-

rudimentary, transitory, non functional rudimentary, transitory, non functional structures that appear early in the 4structures that appear early in the 4thth week. week.

Mesonephroi-Large, elongated excretory Mesonephroi-Large, elongated excretory organs that appear late in the 4organs that appear late in the 4thth week-well week-well developed and function as interim kidneys developed and function as interim kidneys for about 4 weeksfor about 4 weeks

Metanephroi-primordia of permanent Metanephroi-primordia of permanent kidneys-begins to develop in the 5kidneys-begins to develop in the 5thth week. week.

Start to function about 4 weeks laterStart to function about 4 weeks later

Surface AnatomySurface Anatomy Bean shaped organsBean shaped organs Lie retroperitoneally on the posterior Lie retroperitoneally on the posterior

abdominal wall, one on each side of the abdominal wall, one on each side of the vertebral column at the level of Tvertebral column at the level of T1212-L-L33

Normal kidney measures about 12x6x3cm Normal kidney measures about 12x6x3cm and weighs about 140gand weighs about 140g

The right slightly lower position than the The right slightly lower position than the left due to the presence of the liver.left due to the presence of the liver.

They are reddish brown in colourThey are reddish brown in colour Each has anterior and posterior surfaces, Each has anterior and posterior surfaces,

medial and lateral margins, and superior medial and lateral margins, and superior and inferior polesand inferior poles

BoundariesBoundaries Superiorly-diaphragm, suprarenal glands Superiorly-diaphragm, suprarenal glands

superomedially.superomedially. Posteriorly-fibres of the diaphragm and Posteriorly-fibres of the diaphragm and

quadratus lumborum muscles with overlap quadratus lumborum muscles with overlap medially on to the psoas and laterally on to medially on to the psoas and laterally on to transversus abdominis muscles, subscoastal transversus abdominis muscles, subscoastal vein, artery and nerve, iliohypogastric and vein, artery and nerve, iliohypogastric and ilio-inguinal nerve.ilio-inguinal nerve.

Hilum of the kidney lies over the psoas Hilum of the kidney lies over the psoas musclemuscle

Laterally-Aponeurosis of origin of Laterally-Aponeurosis of origin of transversus abdoministransversus abdominis

Boundaries Cont’d..Boundaries Cont’d..

Anteriorly-peritoneum of the Anteriorly-peritoneum of the posterior abdominal wall on each posterior abdominal wall on each side.side.

R kidney-liver duodenum and R kidney-liver duodenum and ascending colonascending colon

L kidney-stomach, spleen, pancreas, L kidney-stomach, spleen, pancreas, jejunum and descending colon.jejunum and descending colon.

StructureStructure

Made up of the cortex and the medullaMade up of the cortex and the medulla The cortex extends towards the pelvis, The cortex extends towards the pelvis,

between a number of triangular darker between a number of triangular darker striated areas called the pyramids of the striated areas called the pyramids of the medulla.medulla.

Apices of several pyramids open together Apices of several pyramids open together into a renal papillainto a renal papilla

Each renal papilla projects into a minor Each renal papilla projects into a minor calyx, which passes into a major calyx.calyx, which passes into a major calyx.

Major calices discharge into renal pelvisMajor calices discharge into renal pelvis

Structure Cont’d..Structure Cont’d..

Histological (and functional) unit of the Histological (and functional) unit of the kidney is the nephronkidney is the nephron

About 1.3million nephrons in each kidneyAbout 1.3million nephrons in each kidney Bowman’s capsule, proximal convoluted Bowman’s capsule, proximal convoluted

tubule, loop of henle (descending and tubule, loop of henle (descending and ascending limbs), distal convoluted tubule, ascending limbs), distal convoluted tubule, the macula densa and the collecting ductthe macula densa and the collecting duct

The renal sinus contains the renal pelvis The renal sinus contains the renal pelvis and the renal vessels.and the renal vessels.

Bloody SupplyBloody Supply

Renal arteries and veinsRenal arteries and veins Arise from the abdominal aorta at the Arise from the abdominal aorta at the

level between Llevel between L11 and L and L22 vertebrae vertebrae The longer right renal artery passes The longer right renal artery passes

posterior to IVCposterior to IVC Each artery divides close to the hilum Each artery divides close to the hilum

into five segmental arteries that are end into five segmental arteries that are end arteries supplying different parts of the arteries supplying different parts of the kidney.kidney.

LymphaticsLymphatics

Renal lymphatic vessels Renal lymphatic vessels follow the renal veins and follow the renal veins and drain into the right and left drain into the right and left lumber (caval and aortic) lumber (caval and aortic) lymph nodes.lymph nodes.

InnervationInnervation

Nerves to the kidneys arise from Nerves to the kidneys arise from the renal nerve plexus.the renal nerve plexus.

Consist of both sympathetic and Consist of both sympathetic and parasympathetic fibersparasympathetic fibers

Renal nerve plexus is supplied by Renal nerve plexus is supplied by fibers from the abdomino pelvic fibers from the abdomino pelvic splanchnic nerves.splanchnic nerves.

THE URETERSTHE URETERS

Muscular ducts (25-30cm long) with Muscular ducts (25-30cm long) with narrow lumina that carry urine from the narrow lumina that carry urine from the kidneys to the urinary bladder.kidneys to the urinary bladder.

Embryologically is of mesodermal, Embryologically is of mesodermal, derived from process of budding from derived from process of budding from the caudal end of the mesonephric duct.the caudal end of the mesonephric duct.

It is a tube of smooth muscle arranged in It is a tube of smooth muscle arranged in 3 layers- innermost circular, 3 layers- innermost circular, intermediate longitudinal and outmost intermediate longitudinal and outmost circularcircular

Lined with transitional epithelium Lined with transitional epithelium

The Ureters Cont’d..The Ureters Cont’d..

Run inferiorly from apex of the renal pelvis Run inferiorly from apex of the renal pelvis at the hila of the kidneys – over the pelvic at the hila of the kidneys – over the pelvic brim at the bifurcation of the common iliac brim at the bifurcation of the common iliac arteries.arteries.

Run along the lateral wall of the pelvis and Run along the lateral wall of the pelvis and enter the urinary bladderenter the urinary bladder

Abdominal parts retroperitoneal throughoutAbdominal parts retroperitoneal throughout 3 points of constriction3 points of constriction

-- At the junction of the ureters and renal At the junction of the ureters and renal pelvispelvis

The Ureters Cont’d..The Ureters Cont’d..

-- Point of crossing over the brim of Point of crossing over the brim of the pelvic inletthe pelvic inlet

-- During passage through the wall During passage through the wall of the urinary bladder.of the urinary bladder.

Those points are potential areas of Those points are potential areas of obstruction by ureteric stonesobstruction by ureteric stones

Blood SupplyBlood Supply

Derived from 4 sourcesDerived from 4 sources Upper part- Ureteric branch of the renal Upper part- Ureteric branch of the renal

arteryartery Middle part-branches from gonadal Middle part-branches from gonadal

artery and in many cases branches from artery and in many cases branches from common iliac artery.common iliac artery.

Lower end-Ureteric branch from either Lower end-Ureteric branch from either the inferior or the superior vesical arterythe inferior or the superior vesical artery

Veins drain into the renal, gonadal and Veins drain into the renal, gonadal and internal iliac veins.internal iliac veins.

LymphaticsLymphatics

Run back alongside the arteriesRun back alongside the arteries Abdominal portion of the ureter Abdominal portion of the ureter

drains into para-aortic nodesdrains into para-aortic nodes The pelvic portion into nodes on The pelvic portion into nodes on

the side wall of the pelvis the side wall of the pelvis alongside internal iliac arteries alongside internal iliac arteries (internal iliac lymph nodes).(internal iliac lymph nodes).

Nerve SupplyNerve Supply

Derived from sympathetic Derived from sympathetic connector cells in the spinal connector cells in the spinal cord from Lcord from L11 to L to L22

CONGENITAL ANOMALIES CONGENITAL ANOMALIES OF THE KIDNEYS AND OF THE KIDNEYS AND

URETERSURETERS Bilateral renal agenesis-when Bilateral renal agenesis-when

metanephric diverticula fail to developmetanephric diverticula fail to develop Malrotated kidneyMalrotated kidney Ectopic kidneys (pelvic kidneys) - failure Ectopic kidneys (pelvic kidneys) - failure

of the kidneys to ascendof the kidneys to ascend Horseshoe kidney-when the poles of the Horseshoe kidney-when the poles of the

kidneys are fusedkidneys are fused Bifid uretersBifid ureters Ectopic ureter-may open into the bladder Ectopic ureter-may open into the bladder

neck, urethra, vagina or vestibleneck, urethra, vagina or vestible Polycystic kidneys-autosomal recessive Polycystic kidneys-autosomal recessive

disorder.disorder.

URINARY BLADDERURINARY BLADDER

Made up of smooth muscle arranged in whorls Made up of smooth muscle arranged in whorls and spirals-detrusor muscleand spirals-detrusor muscle

Lined by transitional epitheliumLined by transitional epithelium When empty, it is located in the lesser pelvisWhen empty, it is located in the lesser pelvis Separated from the pubic bones by retropubic Separated from the pubic bones by retropubic

space (of Retzius)space (of Retzius) Relatively free within the extraperitoneal Relatively free within the extraperitoneal

subcutaneous fatty tissuesubcutaneous fatty tissue Neck held by lateral ligaments of the bladder Neck held by lateral ligaments of the bladder

and pubovesical ligament in femalesand pubovesical ligament in females

URINARY BLADDER URINARY BLADDER Cont’d..Cont’d..

Bladder has four surfaces-the apex, body, Bladder has four surfaces-the apex, body, fundus and neckfundus and neck

Apex points towards the superior edge of Apex points towards the superior edge of the pubic symphysis when the bladder is the pubic symphysis when the bladder is emptyempty

The fundus of the bladder is opposite the The fundus of the bladder is opposite the apexapex

The fundus and inferolateral surface meet The fundus and inferolateral surface meet inferiorly at the neck of the bladderinferiorly at the neck of the bladder

Only superior surface is covered by Only superior surface is covered by peritoneum.peritoneum.

URINARY BLADDER URINARY BLADDER Cont’d..Cont’d..

In females the fundus is directly related to In females the fundus is directly related to the superior anterior wall of the vaginathe superior anterior wall of the vagina

At the bladder neck, the muscle fibers At the bladder neck, the muscle fibers form the involutary internal urethral form the involutary internal urethral sphincter which contracts to prevent sphincter which contracts to prevent retrograde ejaculation in menretrograde ejaculation in men

The ureteric orifice and the internal The ureteric orifice and the internal urethral orifice are at angles of the urethral orifice are at angles of the trigone of the bladder.trigone of the bladder.

Blood SupplyBlood Supply

Arterial supply- branches of the Arterial supply- branches of the internal iliac arteriesinternal iliac arteries

-- Antersosuperior parts- superior Antersosuperior parts- superior vesical arteriesvesical arteries

-- Posteroinferior parts- vaginal Posteroinferior parts- vaginal arteries arteries

-- Others-obturator and inferior Others-obturator and inferior gluteal arteries.gluteal arteries.

Venous DrainageVenous Drainage

Vesical venous plexus drains through the Vesical venous plexus drains through the inferior vesical veins into the internal iliac inferior vesical veins into the internal iliac veins. Occasionally through the sacral veins veins. Occasionally through the sacral veins into the internal vertebral venus plexusesinto the internal vertebral venus plexuses

In female, the vesical venous plexus In female, the vesical venous plexus envelops the pelvic part of the urethra and envelops the pelvic part of the urethra and the neck of the bladder, receives blood the neck of the bladder, receives blood from dorsal vein of the clitoris and from dorsal vein of the clitoris and communicates with the vaginal or communicates with the vaginal or uterovaginal venous plexus.uterovaginal venous plexus.

Lymphatic DrainageLymphatic Drainage

Superolateral aspects-external iliac Superolateral aspects-external iliac lymph nodeslymph nodes

Fundus and neck-internal iliac lymph Fundus and neck-internal iliac lymph nodes, sacral or common iliac lymph nodes, sacral or common iliac lymph nodes.nodes.

InnervationInnervation Sympathetic fibers-inferior thoracic and Sympathetic fibers-inferior thoracic and

upper lumbar spinal cord levels to the upper lumbar spinal cord levels to the vesical (pelvic) plexus through the vesical (pelvic) plexus through the hypogastric plexuses and nodeshypogastric plexuses and nodes

Parasympathetic fibers-sacral spinal cord Parasympathetic fibers-sacral spinal cord levels by pelvic splanchnic nerves and the levels by pelvic splanchnic nerves and the inferior hypogastric nervesinferior hypogastric nerves

Sensory fibers are visceral, reflex afferents Sensory fibers are visceral, reflex afferents follow the course of the parasympathetic follow the course of the parasympathetic fibersfibers

In men, sympathetic innervation that In men, sympathetic innervation that stimulates ejaculation simultaneously stimulates ejaculation simultaneously causes contraction of the internal urethral causes contraction of the internal urethral sphincter to prevent retrograde ejaculation.sphincter to prevent retrograde ejaculation.

THE FEMALE URETHRATHE FEMALE URETHRA

Approximately 4 cm long and 6mm in Approximately 4 cm long and 6mm in diameterdiameter

Passes anteroinferiorly from the internal Passes anteroinferiorly from the internal urethral orifice of the bladder, posterior and urethral orifice of the bladder, posterior and then inferior to the pubic symphysis, to the then inferior to the pubic symphysis, to the external urethral orificeexternal urethral orifice

The musculature surrounding the internal The musculature surrounding the internal urethral orifice of the female bladder is not-urethral orifice of the female bladder is not-organized into an internal sphincterorganized into an internal sphincter

External urethral orifice located in the External urethral orifice located in the vestible, directly anterior to the vaginal vestible, directly anterior to the vaginal orificeorifice

THE FEMALE URETHRA THE FEMALE URETHRA Cont’d..Cont’d..

The axis is parallel to that of the vaginaThe axis is parallel to that of the vagina It passes with the vagina through the pelvic It passes with the vagina through the pelvic

diaphram, external urethral sphincter and diaphram, external urethral sphincter and perineal membraneperineal membrane

Paraurethral glands particularly in the Paraurethral glands particularly in the superior part are homologous to the superior part are homologous to the prostateprostate

The glands have common paraurethral duct The glands have common paraurethral duct which opens on each side (one on each which opens on each side (one on each side) near the external urethral orificeside) near the external urethral orifice

THE FEMALE URETHRA THE FEMALE URETHRA Cont’d..Cont’d..

The urethra is lined entirely with The urethra is lined entirely with transitional epitheliumtransitional epithelium

Wall consists of smooth muscle, with Wall consists of smooth muscle, with a good deal of fibrous tissuea good deal of fibrous tissue

Surrounded by the sphincter Surrounded by the sphincter urethrae, the malfunction of which urethrae, the malfunction of which results in stress incontinence results in stress incontinence

Blood supply and Blood supply and LymphaticsLymphatics

Internal pudendal and vaginal arteriesInternal pudendal and vaginal arteries The veins follow the arteries and have The veins follow the arteries and have

similar namessimilar names Most lymphatic vessels from the Most lymphatic vessels from the

urethra pass to the sacral and internal urethra pass to the sacral and internal iliac lymph nodes. Few from distal iliac lymph nodes. Few from distal urethra drain into the inguinal lymph urethra drain into the inguinal lymph nodes.nodes.

InnervationInnervation

Arise from vesical plexus and the Arise from vesical plexus and the pudendal nervepudendal nerve

Visceral afferents run in the pelvic Visceral afferents run in the pelvic splanchic nerves.splanchic nerves.

Thank YouThank You