Ureter, Urinary Bladder, Urethra Lecture Notes PDF

Ureter Thick walled muscular tube which conveys urine from the kidney to the urinary bladder. It is about 10 inches long Upper half lies in the abdomen & lower half lies in the pelvis Origin: Begins at the lower pole of kidney as a lower continuation of renal pelvis This junction is called pelvi-ure...

Ureter Thick walled muscular tube which conveys urine from the kidney to the urinary bladder. It is about 10 inches long Upper half lies in the abdomen & lower half lies in the pelvis Origin: Begins at the lower pole of kidney as a lower continuation of renal pelvis This junction is called pelvi-ureteric junction Kidney Ureter Urinary bladder Inferior vena cava Right kidney Ureter Left suprarenal gland Abdominal aorta Sacroiliac joint Greater sciatic notch Pelvic brim Ischial spine Sacroiliac joint Course: Runs down on the posterior abdominal wall Crosses the pelvic brim (pelvic inlet) and enters the pelvic cavity Runs downwards and backwards on the lateral wall of pelvic cavity along the greater sciatic notch Reaches the ischial spine Runs forwards and medially reaches the base of the urinary bladder Runs through the wall of the urinary bladder Termination: Terminates by opening into the urinary bladder at the lateral angles of trigone Relations of ureter: Relations of abdominal part: Posterior relations: Psoas major Transverse processes of lumbar vertebrae Genitofemoral nerve, external iliac artery Anterior relations of right ureter: Third part of duodenum, terminal part of ileum Right colic, right ileocolic, right gonadal vessels Peritoneum, root of mesentery Anterior relations of left ureter: Peritoneum Left gonadal vessels, left colic vessels Sigmoid colon and sigmoid mesocolon Anterior relations of the abdominal part of ureters A-Right ureter, B-Left ureter Relations of pelvic part of ureter: Relations during its down ward course: Lateral relations: Obturator internus muscle Superior vesical artery, obturator nerve and vessels Posterior relations: Internal iliac vessels, sacroiliac joint Anterior relations: Ovary (in females) Relations during its forward course In males: Crossed superiorly by the vas deferens Terminal part is situated above the seminal vesicle In females: Runs lateral to cervix of uterus Lies above the lateral fornix of vagina Crossed superiorly by the uterine vessels Relations of the pelvic part of ureter A- Posterior view of urinary bladder showing relations of the ureter B-Anterior view of uterus and vagina showing relations of the ureter Ureter-Male Pelvic organs - female Uterus Right ureter Left ureter Urinary bladder Vagina Urinary bladder Uterus Uterine artery Ureter Obturator nerve and artery Superior vesical artery Ureter- Female Urinary bladder Cervix of uterus Uterine vessels Ureter Ureter-Male Ureter Ductus deferens Seminal vesicle Constrictions of ureter: Lumen of ureter is narrow at 3 regions First constriction – at the pelvi-ureteric junction Second constriction- when the ureter crosses the pelvic inlet Third constriction- when ureter runs in the wall of urinary bladder Blood supply: Upper part -renal, gonadal & colic vessels. Middle part – abdominal aorta, gonadal or iliac vessels Pelvic part - vesical, middle rectal or uterine vessels. Nerve supply of ureter: Nerves reach the ureter through the renal, aortic & hypogastric plexus Contain sympathetic and parasympathetic fibres Sympathetic arise from T10 - L1 spinal segments Parasympathetic from S2 - S4 All the nerves are sensory in function Applied anatomy: Ureteric stone may be impacted at any of the normal constrictions of ureter Renal colic: Severe pain due to a ureteric stones (calculus) which causes spasm of the ureter. Pain starts in the loin, radiates down to the groin, scrotum and inner side of the thigh.(T11 –L2 segments). Urinary bladder Temporary reservoir of urine Situated in the anterior part of pelvic cavity Capacity: 220 ml Its muscle detrusor is arranged in whorls and spirals and is adapted for mass contraction. External features: Empty or semi filled bladder is pyramidal in shape Has: Apex, base and neck Superior and 2 inferolateral surfaces Borders: 2-lateral, one anterior and one posterior. External Features of Empty bladder A-Lateral view, B-Inferior view Apex Urinary bladder Base Median umbilical ligament Rectum Internal urethral orifice Neck Prostate Urinary bladder - male Urinary bladder - female Uterus Urinary bladder Rectum Urethra Vestibule of vagina vagina External urethral orifice Apex: Anterior pointed part Situated near the pubic symphysis Gives attachment to median umbilical ligament Neck: Lowest and most fixed part Presents internal urethral orifice Relations of neck: In males – prostate In females – pelvic fascia Posterior view of male urinary bladder and its relations Base (fundus, posterior surface): Triangular in shape At the superolateral angles ureter enters the urinary bladder Relations: In the females: Vagina In the males: Rectovesical pouch Vas deferens, seminal vesicle, rectum Ureter Vas deferens Seminal vesicle Superior surface: In males: related to coils of ileum In females: related to uterus Inferolateral surfaces: Related to Pubis, retropubic pad of fat, Inferolateral surface Pubis Urinary bladder – inferolateral surfaces Urinary bladder Inferolateral surface Prostate Retropubic pad of fat Prostatic part of urethra Urogenital diaphragm Interior of urinary bladder: Presents mucosal folds Folds disappear when bladder is distended Trigone of bladder: Triangular area without mucosal folds Mucosa is firmly attached to the muscular layer Situated at the lower part of base Has 3 angles – Inferior angle and 2 superior angles Superior angles present openings of ureters Internal urethral orifice situated at the inferior angle Uvula of bladder (vesicae) - elevation at the inferior angle of trigone in males (produced by prostate) Trigone Uvula of bladder Interior of the bladder-coronal section Arterial supply: Superior and inferior vesical arteries Venous drainage: Superior and inferior vesical veins Lymphatic drainage: Internal and external iliac nodes Nerve supply: Vesical plexus of nerves containing sympathetic and parasympathetic nerves Parasympathetic fibres are from S2,S3,S4 nerves Sympathetic fibres are from T11 – L2 spinal segments Structure of urinary bladder Wall of the bladder is made up of 3 layers – mucosa, muscle layer, adventitia Mucosa: Inner most layer, has many folds which project into the lumen Is lined by transitional epithelium Muscle layer: Smooth muscle fibres running in different directions These smooth muscle is called detrusor muscle Adventitia: connective tissue layer Urethra The membranous canal (tube) that leads from the bladder and transports and discharges urine outside the body In males the urethra also carries seminal fluid Urethra Male urethra Fibromuscular tube 18– 20 cm long. In the flaccid state of penis, the long axis of urethra shows two curvatures, and therefore it is S-shaped. In the erect state of penis, the distal curve is obliterated and it becomes J-shaped. It extends from the internal urethral orifice at the neck of the bladder Runs through the prostate, deep perineal space and penis Terminates at the external urethral orifice at the tip of penis (glans penis) Parts: 3 parts Prostatic part passes through the prostate. Membranous part is surrounded by sphincter urethrae. Spongy or penile part passes through the bulb and corpus spongiosum of penis. Urinary bladder Prostate Prostatic part of urethra Membranous part of urethra Deep perineal space Bulbourethral glands Spongy part of Urethra Prostatic part Membranous part Deep perineal space Spongy part Glans penis External urethral orifice Prostatic part: Situated in the prostate, 3 cm long Begins at the internal urethral orifice Terminates by continuing as membranous urethra Most dilated part On transverse section it is semilunar in shape, with its convexity directed forwards. Prostate Features of Prostatic part The posterior wall(floor) of prostatic urethra presents: 1. Urethral crest (verumontanum), a median longitudinal ridge of mucous membrane. 2. Colliculus seminalis is an elevation in the middle part of the crest, on which the slit-like orifice of prostatic utricle is situated. On each side of this orifice there are openings of the ejaculatory ducts. 3. Prostatic sinuses are two vertical grooves situated one on each side of the crest. Each sinus presents about 2030 openings of the prostatic glands. Prostatic Utricle is a blind sac, about 6 mm long, which lies within the prostate. It is directed upwards and backwards between the median and posterior lobes of the prostate. It is homologous with the uterus of females. Membranous part: Shortest (1.5 - 2 cm), narrowest and least dilatable part of male urethra. Situated in the deep perineal space Begins as a continuation of prostatic urethra. It runs downwards and slightly forwards through the sphincter urethrae, and pierces the perineal membrane about 2.5 cm below and behind the pubic symphysis. Terminates by continuing as spongy urethra, On transverse section, it is star (stellate) shaped. Deep perineal space Membranous part Features: 1. Membranous urethra is surrounded by sphincter urethrae (external urethral sphincter). 2. Bulbourethral glands (of Cowper) are placed one on either side of membranous urethra, although their ducts open into spongy part of urethra after piercing the perineal membrane. 3. Numerous urethral glands also open into it. Spongy part of urethra Membranous part Glans penis Bulb of penis External urethral orifice Corpus spongiosum Spongy (penile) part: Longest part (15 cm), situated in the penis Begins as a continuation of membranous urethra The fixed part of penile urethra runs forwards and upwards in the bulb of penis. It bends downwards in front of the lower part of pubic symphysis to continue as the free part of penile urethra in the corpus spongiosum penis. It terminates at the external urethral orifice situate at the tip of the glans penis. It is narrow with a uniform diameter of about 6 mm in the body of penis. It is dilated: (a) at its commencement, to form the intrabulbar fossa on the floor and sides; and (b) within the glans penis, to form the navicular fossa on the roof and sides. External urethral orifice is the narrowest part of male urethra. It forms a sagittal slit about 6 mm long, and is bound on each side by a small labium. On transverse section, the lumen is a transverse opening, except for the external urethral orifice which is vertical. Features: 1. Ducts of bulbourethral glands open in the fixed part of penile urethra about 2.5 cm below the perineal membrane. 2. Except in the most anterior part, there are numerous orifices of the urethral glands (of Littre) facing forwards. 3. In addition, there are several small pit-like recesses or lacunae (of Morgagni) which open obliquely forwards. One lacunae in the roof of navicular fossa is largest (Lacunae magna). Lacunae receives openings of the urethral glands. Sphincters of urethra Internal urethral sphincter (sphincter vesciae): Situated at the neck of the bladder around the internal urethral orifice Its a part of detrusor muscle (of urinary bladder) made of smooth muscle, therefore it is involuntary– supplied by autonomic nerves Primary muscle for prohibiting the release of urine Sphincters of urethra External urethral sphincter (sphincter urethrea): Situated at the deep perineal space around the membranous part of urethra made of skeletal muscle, therefore it is under voluntary control – supplied by pudendal nerve is a secondary sphincter to control the flow of urine through the urethra Lining epithelium of urethra: Transitional epithelium – upper part of prostatic part Pseudostratified epithelium – lower part of prostatic part, membranous part, most of spongy part Stratified squamous non-keratinised – terminal part of spongy part Blood supply: Supplied by blood vessels of prostate and penis Lymphatics: From prostatic and membranous part of urethra passes to internal and external iliac nodes. From spongy part to the deep inguinal, superficial inguinal and external iliac nodes. Development: Anterior wall of prostatic urethra above the opening of the prostatic utricle is derived from Vesicourethral canal. Posterior wall is derived from absorbed portions of the mesonephric ducts. Lower part of prostatic and membranous urethra is developed from definitive urogenital sinus. Penile part of urethra is derived from urethral plate. Female urethra Only 4 cm long and 6 mm in diameter. Developmentally, it corresponds to the upper part of prostatic urethra of males that lies above the opening of prostatic utricle. Begins at the internal urethral orifice at the neck of the bladder, roughly 5 cm behind the middle of the pubic symphysis. It runs downwards and forwards embedded in the anterior wall of vagina, traverses urogenital diaphragm, and ends at the external urethral orifice in the vestibule of vagina. Upper part is lined by transitional epithelium and major lower part is lined by stratified squamous epithelium. The collections of mucous glands one on each side of the upper part of the urethra are called the paraurethral glands (of Skene) which are homologous with the male prostate. Female urethra is easily dilatable, and the catheters or cystoscopies can be easily passed. Female urethra Urinary bladder Urethra Vestibule of vagina vagina External urethral orifice Applied Anatomy Catheterization of bladder: in cases of retention of urine the bladder is catheterised with rubber or metallic catheter one should remember the normal curvatures of the urethra. External urethral meatus is the narrowest part of male urethra. Urethritis: Acute urethritis is commonly cause by gonococcal infection. This gives rise to a purulent discharge from urethra and frequent painful micturition. Hypospadias is a common anomaly in which the urethra opens on the under surface of penis or in perineum. Epispadias is rare and is associated with ectopia vesicae.