Genitourinary Anatomy Summaries

Format: For each organ/system this section summarises:

Basic Function
Relations and location
Structures belonging to it
Layers/lobes
Blood supply, drainage and nerves
Anatomical variations
Common pathology

Kidney
Basic Function
Primarily, final control of salt and water homeostasis. Also a role in waste disposal.

Relations and location
Retroperitoneal, left lies over T12-L3, (right lies lower b/c of liver). Hilum of LK in transpyloric plain.

Posteriorly
Superior pole – diaphragm posteriorly and 12th rib
Lower portion including hilum – psoas maj, quadratus lumborum and transversus abdominus from medial to lateral. Subcostal (T12) and L1 (splits into iliohypogastric and ilioinguinal) nerves posteriorly also.

Anteriorly
Parietal peritoneum, liver, colon, small bowel, pancreas, stomach, spleen.

Structures belonging to it
Medulla and cortex, real columns, papillae, associated arteries and veins, capsule

Layers/lobes
Coverings
Capsule, perirenal fat (innermost), renal fascia, pararenal/nephric fat. Circa five segments supplied by a single segmental artery with 8-18 cone shaped renal lobes in total.

Blood supply, drainage and nerves
Arterial supply
Renal artery, segmental aa (5), interlobar aa (in renal columns), arcuate a, interlobular a (run between lobules in the cortical labrynth), afferent arteriaole, glomerulus, efferent arteriole.

Venous drainage
Peritubular capillaries, stellate vein, interlobular veins, arcuate veins, interlobar veins, renal vein, IVC. Also arterial vasa recta, medullary capillaries, venous vasa recta.

Nerves
Renal nerve plexus – SN from splanchnic nerves and PS from vagus. Adrenal glands get supply from the celiac plexus.

Anatomical variations
Pelvic kidney, horseshoe kidney, abberant renal arteries, unilateral double kidney (both kidneys on one side), polycystic kidney, abberant renal aa causing ureteric obstruction, bifid or duplex ureters.

Common pathology/clinical correlates
Renal cysts: polycystic kidney disease – autosomal dominant. Leads to renal failure
Renal vein entrapment – left renal vein passes between aorta and SMA. Can become compressed.
Renal and calculi – if sharp or larger than ureter lumen (3mm) then will block tube and cause severe pain.

Ureter
Basic Function
Transport of urine to bladder

Relations and location
25-30cm long, run inferiorly from renal pelvis (L1), pass over pelvic brim at bifurcation of common iliac, run along lateral walls of pelvis before entering bladder. Retroperitoneal.

Structures belonging to it
Layers/lobes
Three constrictions 1. Uretopelvic junction as it exits kidney 2. Pelvic inlet as ureter passes over common iliac 3. Uretovesical junction as ureter enters bladder.

Blood supply, drainage and nerves
Arterial supply: 1. Branch of the renal a 2. Branch of the testicular a 3. Branch from the abdominal aorta 4. Branch from the common iliac (sup vesical).

Venous drainage: ureteric veins drain into renal and gonadal veins.

Nerves
From renal nerve plexus supplied by splanchnic and vagus nerves.

Anatomical variations
Bifid or duplex ureters resulting from division or duplication of the ureteric bud in nephrogenesis. Rectocaval ureter also seen where ureter passes behind IVC (uncommon)

Common pathology/ clinical correlates
Ureteric colic: Severe intermittent pain caused by blockage of ureter if stone is sharp or >3mm in diameter. Pain is referred to T11-L2 segments. Pain passes from loin to groin as the stone passes through the ureter. Lithotripsy focuses sound energy on the stone to break it up.
Hydroureter: Blockage causes backup of urine and eventually hydronephrosis.

Bladder
Basic Function
Store urine. Max capacity ~1L. Desire to urinate occurs at 25% capacity.

Relations and location
Hemisphere with boat shape. Walls composed mostly of detrusor muscle. Apex points toward pubic symphysis, fundus is opposite and the only part covered by peritoneum. Neck: above prostate, detrusor muscle forms an involuntary sphincter at this point. Inferiorlateral surfaces enveloped in CT.

Structures belonging to it
Trigone: Triangle formed by neck and two ureteric orifices.
Interureteric crest: Between ureteric orifices, detrusor contraction blocks orifices in micturition.
Uvula vesicae: Elevation at bladder neck, indicates prostate hypertrophy.

Layers/lobes
Mucosa (transitional epi), submucosa, detrusor, fibrous CT/peritoneum.

Blood supply, drainage and nerves
Arterial supply: Superior vesical (supplies anteriosuperior part), inferior vesical/vaginal in females (supply fundus + neck). Both are branches of the internal iliac.

Venous drainage: In males the vesical venous plexus is continuous with the prostatic plexus. In females continuous with vaginal venous plexus. Vesical VP drains via inferior and sup vesical veins to internal iliac veins.

Nerves
SN from vesical plexus – contracts internal sphincter in ejaculation. PN from pelvic splanchnic nerves – motor to detrusor and relax internal sphincter. Both reflexes and pain travel via parasympathetic nerves.

Anatomical variations

Common pathology/ clinical correlates
Female urethra is shorter and more distensible – is easier to insert a catheter. At same time the shorter length makes UTIs more common in females.

Cystocele – loss of bladder support in females can led to herniation of the bladder into the vagina, anterior vaginal wall can protrude out of vestibule.

Bladder rupture – if happens superiorly, urine enters perineum. If happens inferiorly, urine enters perineum.

Posterior abdominal wall
Basic Function
Muscles of posture, hold organs in.

Relations and location
From T12 down to L5

Structures belonging to it
Quadratus lumborum, psoas maj+min, Transversus abdominus, diaphragm, iliacus. Thoracolumbar fascia. Lumbar plexus. Lateral, medial and median arcuate ligaments.

Blood supply, drainage and nerves
Arterial supply: Aorta

Venous drainage: IVC

Nerves
Lumbar nerves cross across.
Subcostal T12
Iliohypogastric L1
Ilioinguinal L1
Lateral cutaneous nerve of the thigh L2, 3
Genitofemoral L1, 2 (lies on psoas muscle)
Femoral L2, 3, 4

Common pathology/ clinical correlates
Because the psoas muscle lies close to kidneys, ureters, cecum, appendix, sigmoid colon, pancreas and lumbar lymph nodes its movement causes pain. Patient lies on unaffected side and has thigh passively extended on affected side (or flexes actively). Pain = positive psoas sign > possibly retrocecal appendix w/appendicitis.

Ovary
Basic Function
Produce gametes and hormones

Relations and location
Almond shape and size. Joined to pelvic wall by the suspensory ligament of the ovary which contains the ovarian artery and vein. Ovarian ligament connects the ovary to the uterus posterior to the uterotubal junction.

Uterine tube: 10cm long, lies in mesosalpinx and forms the superior edges of the broad ligament. Tubes extend posteriolaterally. Parts include infundibulum, ampulla, isthmus and intramural part.

Structures belonging to it
Ovary proper and CT capsule of simple cuboidal grey mesothelium which is continuous with the mesosalpinx and mesometrium.

Blood supply, drainage and nerves
Arterial supply: Both the ovary and fallopian tube are supplied by the Ovarian artery (Branch of aorta). Ascending uterine artery anastamoses with these.

Venous drainage: Ovarian vein – female equivalent of the testicular vein. Can be found in the suspensory ligament of the ovary. RHS – empties into IVC, LHS empties into left renal vein.

Nerves

Anatomical variations

Common pathology/ clinical correlates
Tubal ligation – surgical birth control – can remove a tube segment, stuture or cauterize.
Ectopic pregnancy – see cervical, tubal, abdominal, ampullar, infundibular, ovarian.
Ovarian cyst - Any collection of fluid, surrounded by a very thin wall, within an ovary.

Uterus
Basic Function
Hold, then expel growing foetus.

Relations and location
Pear shaped hollow muscular organ. Usually anteverted (oriented antoeriorly relative to vaginal axis) and anteflexed (bent anteriorly relative to the cervix). Its mass lies over the bladder. Lies in lesser pelvis with its body on top of the bladder (vesicouterine pouch) and cervix between the bladder and rectum (rectouterine pouch).

Structures belonging to it
Ligaments:
Ligament of the ovary – ovary to uterus. Joins uterus posterior to the uterotubal junction.
Round ligament of the uterus – Attached anterioinferior to the uterotubal junction. Passes through deep inguinal ring and its fibres join with the mons pubis. Maintains anteversion of the uterus.
Cardinal ligament – Runs from the cervix and fornix to lateral pelvic wall. Prevents lateral - medial movement. Contains uterine artery and vein.
Utero-sacral ligament – Cervix to sacrum. Prevents anterior movement.
Pubo-cervical ligament – Cervix to pubic symphysis. Prevents posterior movement.
Broad ligament – Double layer of peritoneum running from sides of uterus to pelvic walls. Superior and inferior support. The broad ligament contains the round ligament of the ovary, suspensory ligament of the ovary, the round ligament of the uterus. Its largest part is the mesometrium, also contains mesosalpinx and mesovarium.

Layers/lobes
Perimetrium (peritoneum), myometrium (smooth muscle layer), Endometrium – 2 parts, the stratum functionalis which is cyclic and is shed in menstruation. Stratum basalis which is not shed and forms the new functionalis.

Blood supply, drainage and nerves
Arterial supply: Uterine arteries and vaginal arteries (internal iliac). Also collateral supply from the ovarian artery.
Arcuate arteries – branches of the uterine arteries in the myometrium that give rise to radial branches.
Radial branches – descend into the endometrium and give off Spiral arteries to the stratum functionalis and Straight arteries to the stratum basalis.

Venous drainage: Uterine venous plexus drais into the internal iliac veins.

Lymph drains : External and internal iliac lymph nodes. Lumbar lymph nodes for fundus.

Nerves: Uterovaginal plexus, made of branches of the inferior hypogastric plexus. SN – Lumbar splanchnic nerves > sup hypogastric plexus > inf hypogastric plexus > Uterovaginal plexus > Uterus. Pain follows SN.

Anatomical variations
Retroversion and retroflexion of uterus.

Common pathology/ clinical correlates
Uterine cavity connected to peritoneal cavity.
Prolapse of uterus – retroverted uterus is more likely to prolapse.
1st degree – cervix is in vagina
2nd degree – cervix at the level of the vaginal opening
3rd degree – cervix out of vagina
Procidentia – uterus also comes out of the vagina. Caused by weakness in the supporting muscles and ligaments.

Cystocele – bladder herniates into vagina.
Rectocoele – rectum herniates into vagina.
Hysterectomey – either via vagina or anterior abdominal wall.

Vagina
Basic Function
Receives penis, giving birth.

Relations and location
Musculomembanous tube 7-9cm long extending from the cervix to the vaginal orifice which lies in the vestibule (area between the labia minora).
Anterior – fundus of bladder and urethra
Posterior – rectum and anus
Lateraly – Levator ani and ureters.

Structures belonging to it
Layers/lobes
Three layers: Innermost stratified squamous, muscularis layer, surrounded by fibroelastic adventitia.

Blood supply, drainage and nerves
Arterial supply: Uterine arteries supply superior 1/3. Vaginal aa (internal iliac) and internal pudendal aa (internal iliac) supply lower 2/3.

Venous drainage: Vaginal plexus continuous with uterine plexus > drains via uterine vein into internal iliac vein.

Nerves: Upper ¾ supplied from uterovaginal plexus – SN from lumbar splanchnic nerves, PN from pelvic splancnic nerves. Pain follows PN below cervix. Pudendal nerve supplies lower ¼ of vagina.

Anatomical variations

Common pathology/ clinical correlates
Vaginal fistulae – can see vesicovaginal or rectovaginal.
Pregnancy anesthesia – Pudendal nerve block – only blocks pain in lower vagina so mother can still feel contractions. Spinal anesthesia gives complete anesthesia inferior to waist level. Contractions must be monitored electronically.

Inguinal canal
Basic Function
Passageway for the spermatic cord + ilioinguinal nerve in males and round ligament of the uterus +ilioinguinal nerve in females.

Relations and location
Located just above the median half of the inguinal ligament. Deep inguinal ring just above the midpoint of the inguinal ligament (which extends from PT to ASIS). External inguinal ring is just lateral to the PT.

Structures belonging to it
Lacunar ligament (extension of the inguinal lig) forms medial boundary, external oblique forms anterior wall and floor, post wall – conjoint tendon and transversalis fascia -internal oblique and transversalis abdominus fuse to form conjoint tendon , roof formed by transversalis and internal oblique before fusing to conjoint tendon, floor formed by external oblique and inguinal lig and lacunar ligament.

Common pathology/ clinical correlates
How to find the pubic tubercle – from below not above, find adductor longus, above the insertion is bare bone and above that is the PT – size and shape of orzo.

Inguinal herniae:
Indirect: called the congenital hernia, herniation follows same route as testes descent via internal inguinal ring, herniation begins lateral to inferior epigastric vessels, surgical repair to prevent ischemia and infarction of the herniated bowel. May go into scrotum.

Direct: acquired herniation, wekening of the abdominal wall predisposes to it, bowel herniates through abdominal wall medial to the inferior epigastric vessels within Hesselbach’s triangle (bounded by rectus abdominus, inf epigastric vessels and inguinal ligament). Won’t down spermatic cord, can still go into scrotum.

Cardinal features of a hernia are 1) cough impulse and 2) reducibility.
Direct/indirect? Feel for cough impulse over site of inguinal ring. If yes then indirect.

Hydrocele: can get an unobliterated portion of the processus vaginalis – leads to hydrocele. Can be connected to peritoneal cavity.

In children the internal ring migrates laterally as they grow.

Spermatic cord
Basic Function
Conduit for blood supply for testes and transport of sperm.

Relations and location
In the inguinal canal

Structures belonging to it
3 Layers, 3 arteries, 3 nerves, 3 veins and 3 other structures.
Layers: External spermatic fascia (continuous with external oblique)
Cremasteric fascia (continuation of conjoint tendon – contains cremaster muscle loops)
Internal spermatic fascia (transversalis fascia)

Blood supply, drainage and nerves
Arteries: Testicular a (aorta), artery to the vas (superior vesical a), cremasteric a (inferior epigastric a)

Nerves Ilio inguinal (L1), Cremasteric n - genital branch of the genitofemoral (L1, 2), ANS.

Veins Pampiniform plexus

Others Vas deferens, lymph, processus vaginalis (continuation of peritoneum that has fused).

Common pathology/ clinical correlates
Prone to torsion

Hydrocele: can get an unobliterated portion of the processus vaginalis in the spermatic cord – leads to hydrocele. Can be connected to peritoneal cavity.

Testis + Scrotum
Basic Function
Gamete production

Relations and location
In scrotum

Structures belonging to it
Layers/lobes
Arrangement from innermost to outermost
Testis
Tunica albuginea
Visceral tunica vaginalis – covers testis except where epididymis attaches to testis.
Serous space
Parietal tunica vaginalis - covers testis except where epididymis attaches to testis.
Internal spermatic fascia (transversalis fascia)
Cremaster muscle and fascia (conjoint tendon)
External spermatic fascia (external oblique)
Subcutaneous tissue and dartos m
Skin

Blood supply, drainage and nerves
Arterial supply:
TESTIS
Testicular aa (aorta), Artery to the vas (superior vesical aa > internal iliac aa), Cremasteric aa (inferior epigastric aa > external iliac aa).

SCROTUM
Posterior – Post scrotal branches of the perineal artery (internal pudendal – internal iliac). Anterior – scrotal branches of the external pudendal aa (femoral).

Venous drainage:
TESTIS
Pampiniform plexus – turns to testicular veins: R > IVC, L > L renal vein.

SCROTUM
Scrotal veins – Accompany aa

Nerves
TESTIS – Testicular nerve plexus on testicular arteries, parasympathetic – vagal, sympathetic – T7.

SCOTUM
Ant surface – Anterior scrotal nn (Ilioinguinal n - L1)
Post surface – Posterior scrotal nn (Perineal n > Pudendal n – S2-4)
Anteriolateral surface - Genital branch of the genitofemoral (L1-2)
Posterioinferior surface - Perineal branches of the posterior cutaneous nerve of the thigh (S2-3)

Lymph drainage
TESTIS
Follows testicular aa to para-aortic and caval lymph nodes.

SCROTUM
Superficial inguinal lymph nodes

Anatomical variations
For testicular descent need Processus vaginalus, gubernaculums, abdominal pressure, testosterone.
Cryptorchidism – 4% of males at birth but 1% at 3 months. Describes undescended, impalpable or ectopic testes. Sperm need 33deg to function so too warm if not descended. Greater risk of testicular cancer (1% in men with undecended testes, this is 5-10 times higher than normal)

Common pathology/ clinical correlates
Hydrocele – fluid collects in tunica vaginalis or processus vaginalis. Key signs = can feel a norm al spermatic cord above it, transilluminates, irreducible.
Cryptorchid – 4% at birth, 1% at 3 months.
Hernia – Indirect, direct, femoral. 2% of boys get a hernia, 10% of all hernias in women.
Torsion – Testis twists inside vaginalis b/c of a bell clapper syndrome. 50% salvageable after 12hr
Torsion appendage testis – Hydatid of Morgagni, appendix epididymis, vas abberans sup, vas abberans inf.
Epididymitis – Rare in childhood, generally STI
Trauma – Can usually be treated conservatively.
Tumour – Germ cell tumours have 3 age peaks: Infancy, 25-40, >60. Paratesticular rhabdomyosarcomas 2 age peaks: 5, 16.
Varicocele – 15% of men. Mostly on left side. Bag of worms. Tx indicated for oligospermia, testicular atrophy or symptoms.

Prostate
Basic Function
They produce a thin, milky fluid that comprises approximately 20% of the volume of semen. Amongst other substances it contains clotting enzymes that coagulate the semen after ejaculation.

Relations and location
Cone shaped, base directed superiorly (sup is the apex of the bladder), apex of prostate directed inferiorly. Rectum posteriorly, fat pad anteriorly then pubic symphysis.

Structures belonging to it
Covered by CT capsule rich in smooth muscle. Septa from this capsule penetrate the gland and divide it into lobes that are indistinct in the adult. The zones are seperated by a thin layer of fibroelastic tissue. Ejaculatory ducts, prostatic urethra.

Layers/lobes
Lobes:
Anterior – infront of urethra, no glands only fibromuscular.
Median – contains ejaculatory ducts
Lateral – Largest lobes, lie on the sides, separated by sulcus at posterior, mostly glandular.
Posterior – at inferior aspect of prostate.

Zones
Peripheral – Makes up 70% of the prostate, 70% of cancers arise here. Glandular. Secretions from follicles drain via canals to the posterior wall of the prostatic urethra.
Transitional – Surrounds the prostatic urethra proximal to the veru. Endodermal in origin, 5% of prostate vol, 20% of cancers. BPH also occurs in the transitional zone.
Central – 25% of the prostate, surrounds ejac ducts, 1-5% of prostate cancers.
Anterior fibromuscular – fibromuscular tissue only 5% of prostate wt, 5% of prostate cancers.

Blood supply, drainage and nerves
Arterial supply: Branches from the pudendal, inferior vesical and middle rectal arteries, which are in turn branches of the internal iliac arteries. These also supply seminal vesicles and urethra from preprostatic to intermediate (not spongy).

Venous drainage: Prostatic venous plexus – arises from deep dorsal vein of the penis and connects with the vesical venous plexus., drains to internal iliac veins.

Nerves:
The inferior hypogastric plexus provides sympathetic innervation.
The pelvic splanchnic nerves (S2-S4) provide parasympathetic innervation.
Anatomical variations

Common pathology/ clinical correlates
Prostate cancer
95% Adenocarcinomas
Rare: Sarcoma, Transitional cell carcinoma, Small cell carcinoma, Squamous cell carcinoma.
BPH: Involves the transitional zone

Measurement of serum acid phosphatase (PSA) is a screening measure for carcinoma of the prostate.

Surgical approaches:
Retropubic – open abdominal incision
Perineal approach
Laproscopic

Courtesy of Heath.

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