Reproductive and Genitourinary System PDF

Urethra The urethra begins at the apex of the trigone of the bladder/ internal urethral orifice Urethral epithelium ○ Proximal ⅔ = transitional epithelium ○ Distal ⅓ = stratified squamous epithelium Female Urethra...

Urethra The urethra begins at the apex of the trigone of the bladder/ internal urethral orifice Urethral epithelium ○ Proximal ⅔ = transitional epithelium ○ Distal ⅓ = stratified squamous epithelium Female Urethra Male Urethra 4-5cm long and exits the body between the clitoris and vagina Longer ~ 20 cm Extends from the internal urethral orifice → external urethral 2 sphincters - external & internal urethral sphincter orifice 4 narrowings ○ Short length means increased risk of developing UTI ○ Bladder neck (intramural urethra) Behind the pubic symphysis, in the anterior wall of the vagina ○ Membranous urethra Travels obliquely downward and forward ○ Superior to the navicular fossa Only 1 anatomical sphincter (urethral sphincter) ○ External urethral orifice ○ Somatic innervation of the external urethral sphincter Older males may also show narrowing of the is supplied by the pudendal nerve prostatic urethra ○ Internal sphincter in females is functional rather than Also functions to ejaculate semen anatomic. The bladder neck and proximal urethra constitute the female internal sphincter Rupture of the Urethra Above the urogenital diaphragm → urine will be contained by levator ani within the pelvis (rectovesical space) Below the perineal membrane (e.g. at spongy urethra) ○ No rupture of Buck’s fascia → urine will accumulate within Buck’s fascia ○ Rupture of Buck’s fascia → urine will accumulate within Colles’ and Scarpa’s fascia Sections of the Male Urethra Pre-prostatic Internal urethral orifice (intramural) urethra Site of the internal urethral sphincter - prevents semen entering the bladder Prostatic urethra Passes through the prostate gland Ejaculation duct joins here ○ Ductus deferens ○ Seminal glands Membranous urethra Site of external urethral sphincter - at level of urogenital diaphragm ○ Distal to the membranous urethra = perineal ○ Proximal to the membranous urethra = pelvic Narrowest part of the urethra Spongy (prenile) urethra Contained with corpus spongiosum 2 curves ○ Infrapubic angle ○ Prepubic angle Navicular fossa Widest part of the urethra just before the external urethral orifice External urethral orifice Urethral lumen runs vertical to the penis instead of parallel → spiral stream of urine which cleans the external urethral meatus → decreased likelihood of UTI Anal Triangle Anal Canal Extends from the superior aspect of the pelvic diaphragm to the anus Anorectal junction is the point at which the rectum joint the anal canal ○ This occurs at the level of puborectalis ○ Rectal ampulla = dilation of the rectum shortly before the dentate line 2 sphincter of the anal canal ○ Internal anal sphincter - involuntary Surrounds the superior ⅔ of the anal canal Contraction stimulated and maintained sympathetically ○ External anal sphincter - voluntary Attaches to the perineal body and posteriorly to the coccyx via the anococcygeal ligament Blends superiorly with the puborectalis m. Supplied by mainly S4 via the inferior rectal nerve Structure of the Anal Canal Superior ⅔ of the mucous membrane of the anal canal is arranged in longitudinal ridges (anal columns) ○ Contains terminal branches of the superior rectal a. + v. Inferior end contains anal valves which also demarcate the pectinate line ○ Superior to anal valves are the anal sinuses which exude mucous when compressed The anal canal is surrounded laterally by the ischioanal fossa Pectinate line/ Dentate line Demarcates the junction of the superior anal canal (derived from endoderm/ hindgut) and the inferior part (derived from ectoderm/ proctodeum) Dentate/ Pectinate Line Above the pectinate line Below the pectinate line Arterial supply Superior rectal artery (branch of Middle rectal artery (branch of IMA) internal iliac) Inferior rectal artery (branch of internal pudendal) Venous drainage Internal haemorrhoidal plexus External haemorrhoidal plexus (drains to superior rectal vein → (drains to inferior and middle rectal IMV) veins → internal iliac vein) Prone to varices due to portal hypertension Lymphatic Internal iliac → common iliac → Superficial inguinal lymph nodes drainage lumbar lymph nodes Nervous supply Inferior hypogastric plexus - Inferior anal nerve (branch of only sensitive to stretch pudendal nerve) - sensitive to touch, pain and temperature Ischioanal Fossa Large fascia-lined wedge-shaped spaces between the skin of the anal region and the pelvic diaphragm ○ Apex of each fossa lies superiorly at the origin of the levator ani from the obturator fascia Filled with fat and loose connective tissue ○ This allows infections to spread easily through the rest of the fossa Structures traversing the fossa ○ Inferior anal vessels ○ Perforating branches of S2 and S3 ○ Perineal branch of S4 Boundaries ○ Anteriorly = Colles’ fascia and inferior diaphragmatic fascia/ perineal membrane ○ Posteriorly = gluteus maximus and sacrotuberous ligament ○ Superiorly = levator ani ○ Inferiorly = skin ○ Laterally = obturator internus, obturator fascia and ischial tuberosity ○ Medially = levator ani, external anal sphincter and anal fascia Pudendal Vessels The pudendal canal (Alock canal) is a horizontal passage within the obturator internus fascia (lines medial obturator internus and forms the lateral wall of ischioanal fossa) The lesser sciatic foramen transmits the: ○ Internal pudendal artery ○ Pudendal nerve Prior to entering the pudendal canal, gives of inferior rectal nerves ○ Nerve to obturator internus At the end of the pudendal canal, the artery and nerve bifurcate into: ○ Perineal n. + a. Distributed mainly to the superficial perineal pouch Superficial perineal branch Deep perineal branch Innervates bulbospongiosus, ischiocavernosus, levator ani and external urethral sphincter ○ Dorsal a./ n. of the clitoris/ penis Runs into the deep perineal pouch Runs on lateral side of the internal pudendal artery to the glans Especially sensitive at the distal end Nerves of the Perineum Mainly supplied by the pudendal nerve (S2-S4) - motor and sensory innervation ○ Anterior perineum also receives small innervation from the genital branch of genitofemoral nerve (which courses through the inguinal canal) In men - scrotal skin In women - accompanies the round ligament terminating in the skin of the mons pubis and labia majora Pudendal nerve blocks are administered near the ischial spine