Urinary Tract Lecture - King Saud University PDF

Prof. Altayeb Ahmed Susan Posky Urinary Tract Prof. Altayeb Ahmed 29/12/24 Urinary Tract Prof. Ahmed 1  Anatomy of Urinary System Learning Objectives: Describe the location, relationships, features and neurovascular s...

Prof. Altayeb Ahmed Susan Posky Urinary Tract Prof. Altayeb Ahmed 29/12/24 Urinary Tract Prof. Ahmed 1  Anatomy of Urinary System Learning Objectives: Describe the location, relationships, features and neurovascular supply of the kidneys Describe the relationship of the renal fascia to the kidneys and suprarenal glands Define the term end artery and explain the significance of this with respect to the segmental arteries of the kidneys Describe the structure, length, course and relationships of the ureters including relationship to peritoneum Describe the locations of the 3 constriction points along the ureter and the relationship of these to ureteric colic Describe the location and relationships of the bladder in both sexes, its internal and external features and neurovascular supply Compare the location and shape of the bladder in a newborn and adult. Understand the relationship of the filling bladder to the overlying peritoneum. Understand, in general, the range of developmental anomalies related to kidney, ureter and bladder development Compare and contrast the urethra in the male and female and describe the location and innervation of the urethral sphincters 29/12/24 Urinary Tract Prof. Ahmed 2 Kidneys - Location Upper urinary tract (Kidney & ureter) And Lower urinary tract (Bladder & urethra) Kidneys Location: Retroperitoneal, paravertebral gutters on posterior upper abdominal wall (retroperitoneal, in paravertebral gutters) Surface marking: Epigastric, Hypochondrial, Lumbar, and Umbilical regions Color: Reddish brown Size: approx 10 x 5 x 2.5cm, Each kidney has: 2 poles (superior pole thicker & rounder), 2 surfaces (ant, post), and 2 borders (medial, lateral). 29/12/24 Urinary Tract Prof. Ahmed 3  Kidneys - Location Levels: Approx T12-L3 levels (supine), tilted in 2 planes (sup. poles closer; ant. surfaces faces slightly laterally) The right kidney is 1/2 inch lower than the left kidney. The left kidney reaches up to the 11th rib while the right kidney reaches only to the 11th space. – Hilum of the left kidney lies near the transpyloric plane (L1), approximately 5 cm from the median plane – Transpyloric plane passes through the superior pole of the right kidney, which is approximately 5.5 cm lower than the left pole (presence of the liver). The inferior pole of the right kidney is approximately a finger’s breadth superior to the iliac crest Movement: kidneys move vertically during respiration (2-3 cm, , approx height of one vertebral body) & from supine to upright position. 29/12/24 Urinary Tract Prof. Ahmed 4 Kidneys – External Features, Blood supply Renal hilum Capsule Renal capsule Renal sinus R. suprarenal v. Kidney (renal parenchyma) Hand-drawn D. Bryce Superior pole Suprarenal gland L. suprarenal v. Renal Lateral border SMA vascular Renal a. pedicle Anterior surface Renal v. Renal pedicle Hilum Renal (vertical cleft pelvis on medial border) most posterior Ureter structure at hilum Inferior pole R. gonadal v. L. gonadal v. Renal capsule (dense, fibrous → glistening appearance), extends into renal sinus. Renal hilum is a 1 cm long cleft on medial border through which structures enter/exit, hilum leads into renal sinus. Structures passing through hilum include renal a.& v. renal pelvis, nerves, lymphatics (VAPA). L renal vein longer, it passes in angle between SMA & abdominal aorta. R renal artery passes behind IVC 5 29/12/24 Urinary Tract Prof. Ahmed  Kidneys – Internal Features Cortex Two nephrons and relationship to light reddish brown, renal parenchyma granular appearance (due to many capillaries) has Medullary rays Renal arches and Renal striation extending from columns the bases of the renal Cortex pyramids into cortex Renal papilla Minor calyx Medulla Nephrons (pyramid) Collecting Pyramid tubule base and apex (papilla) Major calyx Renal papilla Renal cortex extends between pyramids as renal columns. Renal pelvis Renal medulla = collection of renal pyramids Renal (8-15 average = 12). Renal pyramids contain column collecting tubules which open at renal papilla Fat in renal sinus (apex of pyramid). Renal papilla indents each minor calyx (calyx Renal lobe L. = wine glass) → join to form major calyces Pyramid plus (2-3 → join to form renal pelvis (pelvis L. = some cortical tissue funnel-shaped)→ narrows to form ureter Ureter Renal sinus contains fat, minor and major Capsule calyces, renal pelvis, brs of renal aa, (fibrous; → glistening appearance; peels off easily in a healthy tributaries of renal vv, nerves, lymphatics kidney) 29/12/24 Calyx (singular); calyces (plural) 6 Urinary Tract Prof. Ahmed Kidneys – Posterior Relations Right kidney Left kidney Diaphragm Diaphragm separating separating kidneys Superiorly kidneys from 11th + 12th from 12th rib and rib and pleura pleura Inferomedial Psoas major Quadratus lumborum “QL” Subcostal nerves and vessels (b/w kidney and Lower QL) middle iliohypogastric nerve (b/w kidney and QL) Ilioinguinal nerve (b/w kidney and QL) Inferolateral Transversus abdominus 29/12/24 7 Urinary Tract Prof. Ahmed  Kidneys – Anterior Relations Right kidney Left kidney Superomedial - Suprarenal gland (extend to the hilum) Superomedial - Suprarenal gland Superolateral - Spleen and splenorenal ligament - 2nd part of the duodenum (small intestine): Hilum (medial) - Stomach (separated by lesser sac) potential injury during laparoscopic nephrectomy Upper middle - Splenic vessels (along upper border of body of - Right lobe of liver: separated by peritoneum. pancreas) Parietal peritoneum runs as the hepatorenal Upper middle Middle - Body/tail of pancreas ligament to the liver. Excessive downward traction on the kidney can lead to a capsular tear. - Transverse colon Inferolateral - Right colic (hepatic) flexure/ascending colon Inferolateral - Left colic (splenic) flexure - Descending colon - Jejunum - jejunum (Small intestine) inferomedial inferomedial - Ascending branch of right colic artery - Ascending branch of left colic artery 29/12/24 Urinary Tract Prof. Ahmed 8  Kidneys – Renal Fascia & Fat Perinephric fat surrounds the capsule and extends into the renal sinus Renal fascia (Gerota or perinephric fascia): a condensation of extraperitoneal tissue surrounds each kidney and suprarenal gland but a thin fascial septum separates the gland from kidney. It send collagen bundles through the paranephric fat. Inferiorly deficient Medially: Unsheathes the renal vessels Inferomedially: periureteric fascia Paranephric fat lies superficial to the renal fascia and is thickest posteriorly and laterally and is part of body fat. The fat and fascia help to maintain the position of the kidney. Loss of supporting fat (e.g., anorexia) → renal ptosis with potential kinking of ureters → hydronephrosis. Attachments of renal fascia determines direction of spread of infection (renal abscess) & blood (injury) → spreads inferiorly (pelvis). Urinary Tract Prof. Ahmed 9 29/12/24  Kidneys – Blood supply L & R renal aa. from abdominal aorta (~LV2 level); ~20-25% cardiac output. Accessory renal artery in ~30% of population (Aorta). Reduced blood pressure e.g., massive haemorrhage → widespread cell death. Renal artery divides into anterior and posterior branches which gives 5 Segmental aa. are end arteries, consequently blockage (e.g., embolus from L side of heart) → necrosis of that segment of kidney. Urinary Tract Prof. Ahmed 10 29/12/24 Kidneys – Blood supply Lobar a. Lobar a. lobar vein Segmental a. divides to into lobar a. (one for each pyramid), each lobar artery gives off two or three interlobar a. on sides of the renal pyramid. Interlobar arteries at the junction of the cortex and the medulla give arcuate arteries- arch over the bases of the pyramids. These divides to interlobular arteries which later divide to Afferent arterioles to glomerulus to efferent arteriole to peritubular capilaries (primary in cortex) and vasa recta (in medulla) Lobar vein 29/12/24 Urinary Tract Prof. Ahmed 11 Kidneys – Blood supply Lymphatic drainage: Parenchymal, subcapsular, and perirenal plexuses drain into lateral aortic (lumbar) nodes. Lumbar nodes drain through lumbar lymphatic trunks into cisterna chyli. Stability: The following factors keep the kidney in position: Its position in paravertebral gutter. Its coverings. Intra-abdominal pressure. Apposition of neighboring viscera. Renal vessels. Urinary Tract Prof. Ahmed 12 29/12/24  Kidney innervations and clinical notes The renal plexus (sympathetic): accompanies renal artery, enters the kidney through the hilum. Afferent fibers: T10-12. Parasympathetic from vagus action unknown Renal caliculi causes sever colicky pain felt at the flanks or in the loin that may radiate downward into the lower abdomen (T12). Renal pain can result from stretching of the kidney capsule or spasm of the smooth muscle in the renal pelvis. 29/12/24 Urinary Tract Prof. Ahmed 13 Ureters – Abdominal Part Ureters – expansile tubes of smooth muscle ; 25-30 cm long, 3-5 mm wide, extend from renal pelvis to bladder (ureteric orifice), upper ½ in abdominal cavity, lower ½ in pelvic cavity Course: Abdominal course: retroperitoneal; almost vertical on psoas major m. in abdominal cavity separate it from the transverse processes of the lumber vertebrae 29/12/24 Urinary Tract Prof. Ahmed 14  Ureter- Abdominal Relations Right Left Renal vessels Renal vessels Anterior 3rd part of duodenum Body of pancreas Peritoneum Jejunum 4 arteries: Peritoneum - R. gonadal artery 4 arteries: - R. colic artery - L. gonadal artery - Ileocolic artery - L. colic artery - Superior mesenteric artery - 2 sigmoid arteries Root of mesentery (containing SMA) and Terminal part of Apex of the sigmoid mesocolon and Sigmoid colon ileum Medial border of psoas major and psoas minor Posterior Tips of transverse processes of L2-L5 vertebrae Genitofemoral nerve crosses behind the ureter Medial Inferior mesenteric vein lies along the medial side of the left Inferior vena cava ureter 29/12/24 Urinary Tract Prof. Ahmed 15  Ureters – Pelvic Part Course: Midpoint crosses enters the pelvis by crossing the bifurcation of the common iliac a. or beginning of external iliac artery in front of the sacroiliac joint. Pelvic course: – Extraperitoneal; from pelvic brim passes posterolaterally on pelvic wall, then at level of ischial spine turns medially and anteriorly passes obliquely through the posterolateral wall of the base bladder wall so that ureters are approx 5cm apart externally and 2.5cm apart internally; ends at ureteric orifice in urinary bladder. 29/12/24 Urinary Tract Prof. Ahmed 16 Ureters – Pelvic relations in Female Laterally Posteriorly Obturator internus fascia Internal iliac artery/vein External iliac vessels Commencement of anterior Superior vesical artery trunk of internal iliac artery Obturator nerve and vessels Lumbosacral trunk Inferior vesical vein Sacroiliac joint Middle rectal artery Pelvic relationships in female: posterior to ovarian vessels at pelvic brim and posterior to ovary on pelvic wall; inferior to uterine artery (water under bridge); ~ 2cm lateral to cervix of uterus and lateral fornix of vagina. 29/12/24 Urinary Tract Prof. Ahmed 17 Ureters – Pelvic relations in Male Laterally Posteriorly Obturator internus fascia Internal iliac artery/vein External iliac vessels Commencement of anterior trunk of internal iliac Superior vesical artery artery Obturator nerve and vessels Lumbosacral trunk Inferior vesical vein Sacroiliac joint Middle rectal artery Pelvic relationships in male: inferior to ductus deferens (water under bridge) near base of bladder 29/12/24 Urinary Tract Prof. Ahmed 18  Ureter Blood Supply – Arterial supply: Upper part Middle portion Pelvic part (branches of internal iliac) Renal artery Gonadal artery Superior vesical artery Abdominal aorta Uterine artery (in female) Common iliac artery Middle rectal artery Vaginal arteries (in female) Inferior vesical artery (in male) – Venous blood drains into veins correspond to arteries Lymph Drainage: upper part the lateral aortic and iliac nodes middle part to common iliac LNs and inferior part to common, external and internal iliac LNs. Branches approach the ureters medially and Nerve Supply: is from renal, testicular (or ovarian)/aortic, and divide into ascending and descending hypogastric plexuses (in the pelvis). branches, forming a longitudinal anastomosis – Afferent fibers L1-L2 segments on the ureteric wall; if arterial supply damaged during surgery (e.g., traction) may result in – Sympathetic : T10/11 – L1 segments necrosis and leaks or ruptures 7-10 days post – Parasympathetic : S2 – S4 segments surgery 29/12/24 Urinary Tract Prof. Ahmed 19  Urinary Bladder – Location, Shape Spindle / fusiform shape Empty bladder in newborn is in abdominal cavity Empty bladder in adult is in pelvic cavity Empty bladder in adult is entirely within pelvic cavity (not felt on Examination) ; desire to void ~250-300 mls, normal capacity 500ml. – Bladder is boat-shaped when empty and spherical as it fills. As it fills it rises into abdominal cavity and peritoneum is stripped from anterior abdominal wall (→ possible to access bladder by suprapubic approach without entering peritoneal cavity). Empty bladder in newborn is spindle-shaped and abdominal in position and more prone to abdominal injuries than adult; begins to enter pelvis at ~ age 6-7yrs. Rupture of bladder (e.g. pelvic fracture): if empty, urine → extraperitoneal tissue; if full, urine → peritoneal cavity 20 29/12/24 Urinary Tract Prof. Ahmed  Urinary Bladder – External Features Structure: lined by transitional epithelium; smooth muscle (detrusor m.; Latin - to force out) arranged in interlacing bundles External features: Superior surface covered by peritoneum 2 inferolateral surfaces rest on pubic bone (ant) & levator ani & obturator internus mm (lat) Base (fundus) faces posteriorly, an inverted triangular shape. Upper part is covered by peritoneum in males only. Ureters enter posterolateral aspect of base and urethra exits inferiorly Apex lies anteriorly, connected to umbilicus by urachus/median umbilical ligament (vestigial structure). Neck is lowest, most fixed (by ligaments:- Puboprostatic ligaments (male) and Pubovesical ligament (female) part of bladder. Smooth muscle of neck forms sphincter vesicae (internal urethral sphincter). 29/12/24 Urinary Tract Prof. Ahmed 21  Bladder – Relations in Female Midsagittal section - Female Coils of intestines (above bladder in both sexes) Anterior: retropubic space and pubic bone/pubic symphysis Superior: uterovesical pouch, coils of intestines and body of uterus Inferolateral: retropubic pad of fat , pubic bones, Upper part obturator internus m , nerve and artery Lower part levator ani m. (is a part of pelvic diaphragm). Posterior: cervix of uterus and vagina (not rectum) 29/12/24 22 Urinary Tract Prof. Ahmed  Bladder – Relations in Male Coils of intestines Rectum Obturator internus Levator ani Prostate Ductus (vas) deferens Coronal section - male Seminal vesicle Prostate Retropubic space (and fat) Pubic symphysis Bladder – Midsagittal male pelvis posterior aspect in male Anterior: retropubic space and pubic bone/pubic symphysis and abdominal wall (if full) Superior: peritoneum and is related to coils of ileum or sigmoid colon Inferolateral: retropubic pad of fat , pubic bones, Upper part obturator internus m , nerve and artery Lower part levator ani m. (is a part of pelvic diaphragm). Inferior: prostate Posterior: in upper part- peritoneum forming the anterior wall of the rectovesical pouch. In lower part- separated from the rectum by the vasa deferentia, seminal vesicles, and rectovesical fascia “Denonviller” 29/12/24 Urinary Tract Prof. Ahmed 23 Urinary Bladder – Internal Features Rugae (folds of mucosa) Detrusor muscle (Detrusor L. to force out) Ureteric orifice Trigone (mucosa smooth; least distensible part) Interureteric ridge/crest Uvula vesicae in males only (bulge above int. urethral orifice produced by underlying median lobe of prostate gland) Sphincter vesicae Internal urethral orifice (internal urethral sphincter) (commencement of urethra) Sphincter urethrae Prostate gland (in male, not female) (external urethral sphincter) Coronal section through bladder in male Internal features: rugae (folds of mucous membrane in empty bladder – folds disappear as bladder distends); trigone is triangular area situated posteriorly and limited by 2 ureteric orifices (oblique, slit-like) and an internal urethral orifice, an interureteric ridge/crest extends between the ureteric orifices. Mucosa of trigone is always smooth (closely bound to underlying muscle; absence of submucosa here). 24 29/12/24 Urinary Tract Prof. Ahmed  Urinary bladder Blood Supply – Arteries: Superior vesical (anterosuperior parts) and inferior vesical (male)/ vaginal artery (female) (fundus and neck) arteries, from internal iliac. Vaginal arteries also send small branches to postero-inferior parts of the bladder Small branches from obturator and inferior gluteal arteries – Veins: In males veins form vesical venous plexus communicates with the prostatic plexus, drains into internal iliac vein. In females, vesical venous plexus envelops the pelvic part of the urethra and the neck of the bladder, receives blood from the dorsal vein of the clitoris, and communicates with the vaginal or uterovaginal venous plexus Lymph Drainage: Internal (Base, neck and posterior) and external iliac (superior and lateral surfaces) nodes. 29/12/24 Urinary Tract Prof. Ahmed 25 Urinary bladder Nerve supply Inferior hypogastric plexuses. – Sympathetic from L1 and 2 ganglia Inhibit contraction of detrusor muscle and stimulate closure of sphincter vesicae – Parasympathetic arise as the pelvic splanchnic nerves from S2-S4 Stimulate contraction of detrusor muscle and inhibit action of sphincter vesicae. Afferent sensory fibers: – Parasympathetic (most) – S2-S4 segments – Sympathetic (some) – L1-L2 segments 29/12/24 Urinary Tract Prof. Ahmed 26  URETHRA Fibromuscular tube extends from urinary bladder to external urethral meatus Layers: – Mucosa: is a protective mucous membrane houses clusters of mucin-producing cells called urethral glands. – Muscularis: primarily smooth muscle fibers (propulsive function) Two urethral sphincters: Internal urethral sphincter (Superior) External urethral sphincter (Inferior) Location b/w neck of bladder and prostate In the deep perineal pouch (urogenital diaphragm) Surrounds Neck of bladder/pre-prostatic part of Membranous part of urethra urethra Type of Smooth muscle Skeletal muscle muscle Control Involuntary Voluntary Nerve supply Autonomic Deep perineal branch of pudendal n. 29/12/24 Urinary Tract Prof. Ahmed 27 Urethra – Female Bladder Internal urethral orifice (Sphincter vesicae) Sphincter urethrae Vagina External urethral orifice Vestibule is region between 2 labia minora Midsagittal female pelvis Coronal section - Female Commences at internal urethral orifice at neck of bladder, ends at external urethral orifice (vestibule, between vagina and clitoris). Approximately 4 cm long, relatively distensible (up to 1cm); passes anteriorly and inferiorly (important to understand for catheterisation), passes through pelvic diaphragm, surrounded by sphincter urethrae (external urethral sphincter; skeletal muscle, voluntary). Urethra fused with anterior wall of vagina. Due to short course of the urethra, females are prone to lower urinary tract infections (cystitis & urethritis → pain, frequency & urgency). 28 29/12/24 Urinary Tract Prof. Ahmed  Midsagittal male pelvis Urethra – Male Internal urethral orifice Sphincter vesicae (internal urethral sphincter - at bladder neck) Preprostatic urethra Urethral crest Prostatic Prostatic sinus urethra (most distensible) Membranous Seminal urethra colliculus (least distensible) (with opening of ejaculatory Sphincter urethrae ducts & (external urethral utricle) sphincter) in the urogenital diaphragm Posterior wall of urethra Perineal membrane Intrabulbar fossa (receives secretions of bulbourethral glands via ducts 2.5cm long) Spongy urethra Navicular fossa(fossa terminalis) – dilated distal part (opening of mucous glands in roof- lacuna magna, catheter may catch) External urethral orifice (narrowest part) Male urethra. commences internal urethral orifice at neck of bladder, ends at external urethral orifice (tip of glans penis – narrowest part). Approximately 20 cm long, 4 parts: preprostatic (through bladder neck); prostatic (~3 cm); membranous (~ 1cm; though sphincter urethrae and perineal membrane; least distensible); spongy or penile (~15 cm, through bulb, corpus spongiosum & glans penis). The prostatic part (widest & most dilatable part) has a posterior ridge – urethral crest, with an elevation (seminal colliculus or verumonatum) that receives openings of the ejaculatory ducts and utricle; the prostatic sinus (the recess on sides of urethral crest) receives the openings of ducts of prostate gland. 29 29/12/24 Urinary Tract Prof. Ahmed  Urethra Urethra Male Female Arterial supply Prostatic branches of inferior vesical, middle rectal, Internal pudendal and vaginal arteries dorsal artery of the penis Venous supply Prostatic venous plexus Internal pudendal and vaginal veins lymphatics Internal iliac nodes Sacral and internal iliac nodes Distal urethra → inguinal nodes (mostly deep) Distal urethra → Superficial inguinal nodes (mostly superficial) Nerves Vesical (nerve) plexus, Prostatic plexus (inferior Vesical (nerve) plexus hypogastric). The dorsal nerve of the penis somatic to Pudendal nerve spongy part. 29/12/24 Urinary Tract Prof. Ahmed 30  Kidney Arteries often variable, in up to 30-40% of cases Variations include accessory renal arteries (in addition to main) and pelvic branches with pelvic or horseshoe kidneys Renal veins: usually single Long course of left renal vein passes anterior to aorta and under superior mesenteric artery (nutcracker configuration). 29/12/24 Urinary Tract Prof. Ahmed 31 Kidneys - Clinical Bimanual palpation of R kidney Left perirenal abscess Enlarged left kidney vs enlarged spleen - easy to confuse but: Kidney retroperitoneal and can feel space between enlarged kidney & costal margin (but not between spleen and costal margin) Kidney moves inferiorly with inspiration, but spleen moves obliquely (towards umbilicus) Percussion usually resonant over kidney (due to gas in overlying bowel) but dull over spleen Notched border of spleen may (or may not) be palpable 29/12/24 Urinary Tract Prof. Ahmed 32 Ureters – Obstruction Obstruction of upper part of ureter (pelviureteric jn) → hydronephrosis Obstruction of lower part 3 sites of constriction/narrowing along ureter. of ureter → hydroureter Significance: ureteric calculus may lodge here.(narrowest is vesico-ureteric) and hydronephrosis → +/- ureteric colic (loin to groin pain); → +/- hydroureter and hydronephrosis (with progressive renal parenchymal damage) 29/12/24 33 Urinary Tract Prof. Ahmed  Pain – Kidneys, Ureters, Bladder Pain usually posterior - loin/flank Tenderness to percussion in costovertebral (renal) angle (ie between 12th rib & vertebral column, lateral to back mm.) Suprapubic pain urinary bladder Loin to groin pain colicky & intense Sympathetic nerve supply to kidneys & ureters from ~ T10/11-L1 spinal cord, vasomotor, visceral pain afferents travel with sympathetic fibres back to same levels of spinal cord. Renal pain usually referred to back. Ureteric pain (eg. ureteric stone obstruction) pain starts in loin and radiates to groin (inguinal region, labium majus/scrotum), and is usually intense and spasmodic (ureteric colic) +/- nausea and generalised sympathetic response. Bladder: visceral pain fibres from superior part travel with sympathetic nn to L1 spinal cord (suprapubic pain); rest with parasympathetic fibres → S2-4 spinal cord34 29/12/24 Urinary Tract Prof. Ahmed  Kidney- Clinical notes Renal Mobility (Nephroptosis) Palpation of Kidneys Ascent of the kidney Kidney Trauma Malignant tumor Renal Pain Renal Abscess Tumors e.g., Wilms Tumor 29/12/24 Urinary Tract Prof. Ahmed 35 Complications of Prostatic Hyperplasia Complications of Benign Normal Pouch of Enlarged median stagnant Prostatic Hyperplasia lobe of prostate urine Dilated renal Bladder pelvis wall Kidney Hydronephrosis Ureter Hydroureter Impeded outflow of urine → diminished force (weak stream), hypertrophy of Hyperirritability, bladder wall, reflux into hypertrophy, ureter, incomplete emptying, diverticula retained urine, urinary tract infection Inflammation of bladder mucosa (infection) → pain, frequency, urgency Urinary bladder Urinary retention and reflux Impeded outflow 29/12/24 of urine 36 Hypertrophy and trabeculations of bladder wall Urinary Tract Prof. Ahmed 29/12/24 Urinary Tract Prof. Ahmed 37  Urethra – Male Catheterisation Suprapubic catheter (extraperitoneal approach) Peritoneum Cystoscopy Urethral catheter Catheterisation: urethral catheter (e.g., monitor urine output, collect uncontaminated specimen, relieve acute urinary retention). Male urethra longer and 2 bends in flaccid state, care needed to avoid urethral injury. External urethral orifice is narrowest part, tip of catheter initially directed down to prevent its obstruction at lacuna magna (in roof of navicular fossa), care needs to be taken below perineal membrane and force avoided at narrow, least distensible membranous part. Rupture of spongy urethra (below perineal membrane) e.g., straddle injury → blood & urine extravasation into region; spread is limited by attachments of membranous layer of superficial fascia (swelling & discolouration of scrotum & penis, not into thigh) – see images next slide. 29/12/24 Urinary Tract Prof. Ahmed 38  Clinical Uretheral Stricture Urinary Bladder stone staghorn stone 29/12/24 Urinary Tract Prof. Ahmed 39  Urethral Rupture Urine & blood Perineal membrane Extravasation of urine and blood Rupture above perineal membrane → superficial perineal pouch Rupture below perineal membrane 29/12/24 Urinary Tract Prof. Ahmed 40  Micturition Controlled by higher centres Young child – simple stretch reflex Adult – reflex inhibited by cerebral cortex until convenient time & place Spinal cord Sensory fibres Bladder wall Sphincter vesicae S2-4 segments of spinal cord (internal urethral sphincter) Prostate Pelvic splanchnic nerve (parasympathetic, S2-4, involuntary) Sphincter urethrae Pudendal nerve (S2-4) (external urethral sphincter) (somatic, voluntary) Visceral afferents detect bladder stretch; stretch information travels with pelvic splanchnic nn →S2-4 segments of spinal cord → connections to higher centres → desire to micturate. Micturition inhibited by higher centres until a convenient time. Pelvic splanchnic nn. (parasympathetic from S2-4 spinal cord) → contraction of detrusor muscle and relaxation of sphincter vesicae. Voluntary component involves relaxation of pelvic diaphragm & sphincter urethrae and increase in intraabdominal pressure. Higher centres do not control micturition until ~3 years, prior to this bladder empties reflexly. 41 29/12/24 Urinary Tract Prof. Ahmed  References K.L. Moore and A. Dalley. Clinically Orientated Anatomy. 9th Ed. Netter’s Clinical Anatomy. Netter F. Atlas of Human Anatomy. 2nd Ed. 29/12/24 Urinary Tract Prof. Ahmed 42