Male Reproductive System PDF

XY2141. ANATOMY. MALE REPRODUCTIVE SYSTEM Prepared by Dr Viktoriia Yerokhina, Presented by Nussrat Kazmi [email protected]  LEARNING OUTCOMES ANAT.30 - Male U/G tract ANAT.30.01 - Describe the relationship of the bladder, prostate glan...

XY2141. ANATOMY. MALE REPRODUCTIVE SYSTEM Prepared by Dr Viktoriia Yerokhina, Presented by Nussrat Kazmi [email protected]  LEARNING OUTCOMES ANAT.30 - Male U/G tract ANAT.30.01 - Describe the relationship of the bladder, prostate gland, ductus deferens, seminal vesicles, ejaculatory ducts and rectum in the pelvic cavity. ANAT.30.02 - Describe the course of the ureter along the posterior abdominal wall to the bladder. ANAT.30.03 - Explain what is meant by "water under the bridge". ANAT.30.04 - Define the retropubic space. ANAT.30.05 - Discuss the structures which support the urinary bladder. ANAT.30.06 - Review the internal anatomy of the urinary bladder. ANAT.30.07 - Compare the innervation of the internal and external urethral sphincters. ANAT.30.08 - Compare and contrast the male versus female urethra. ANAT.30.09 - Explain why lower urinary tract infections are more common to females than in males. ANAT.30.10 - Describe the muscles and nerves ( visceral afferent, somatic efferent, sympathetic, parasympathetic) involved in the normal micturition and urinary continence. ANAT.30.11 - Summarize the relationship of the prostate gland and ampulla of the ductus deferens and seminal vesicles to the wall of the rectum. ANAT.30.12 - List the divisions of the male urethra. ANAT.30.13 - Discuss the nervous pathways for control of erection and ejaculation. ANAT.30.14 - Review the anatomical lobes of the prostrate gland and the relationship of the median lobe and posterior lobe to the ejaculatory ducts. ANAT.30.15 - List the lobes of the prostate and the symptoms most commonly involved in benign prostate enlargement. ANAT.30.16 - Explain why prostate cancer usually is leading to erectile and urinary dysfunction. Identify the nerves involved in this process. ANAT.30.17 - List the common sites of prostate cancer metastasis and explain how prostate cancer cells travel to the central nervous system.  OVERVIEW OF MRS Male genital organs include: intenal male organs (testes, epididymides, ductus deferentes, seminal glands and prostate) external male genitalia (scrotum and penis) Male urethra is both an internal and external genital organ (cranial part is internal; caudal part within the penis is external). Testes are located outside the peritoneal cavity → slightly lower temperature of 32–34 °C → optimal for spermatogenesis. OVERVIEW OF MRS  TESTES Testes are a pair of genital glands located outside the abdominopelvic cavity in the scrotum. Orchis is the Greek term for testis. During prenatal development, they originate in the lumbar region and descend through the retroperitoneal space and inguinal canal to reach the scrotum. Layers of the abdominal wall form the layers of scrotum as the testes passes through them. Testicular vessels descend with the testes, hence the origin of these arteries in lumbar region of the abdomen. Lymphatic drainage is similarly directed to the lumbar nodes. Testosterone and spermatozoa are produced in the testes.  EXTERNAL STRUCTURE OF THE TESTIS 1. Upper pole 2. Lower pole – attachment of the scrotal ligament to the testis 2.1 Scrotal ligament (l. scrotale) – ligament attaching the lower pole of the testis and epididymis to the scrotum 3. Anterior border – anterior margin facing the tunica vaginalis 4. Posterior border – posterior margin facing the epididymis 5. Medial surface – medial surface facing the septum of the scrotum 6. Lateral surface  EXTERNAL STRUCTURE OF THE TESTIS 7. Tunica vaginalis – originally a part of peritoneum that became one of the layers of the scrotum during the descent of the testis – composed of two layers with a slender slit between them 7.1 Parietal layer (periorchium) 7.2 Visceral layer (epiorchium) 7.3 Cavum serosum scroti – a cavity between the parietal and visceral layers.  DESCENT OF TESTIS Descended testes (testes in situ) is an important sign of maturity of the newborn. Spermatogenesis is only possible in testes positioned inside the scrotum. Timeline: complete by week 33  VASCULAR SUPPLY Arterial supply: 1. Testicular artery (from abdominal aorta), partially: artery to ductus deferens (from internal iliac artery), cremasteric artery (from inferior epigastric artery)  VASCULAR SUPPLY Venous drainage: 2. Pampiniform plexus and then testicular veins 2.1 Right testicular vein – to inferior vena cava (IVC) 2.2 Left testicular vein – to left renal vein Pampiniform plexus and the testicular veins work as a counter-current blood cooling system. Lymphatic drainage: 3. Lumbar nodes  CLINICAL CORRELATION Testicular torsion describes an acute situation when the testis twists around the vessels passing in the spermatic cord. Symptoms: swelling of the scrotum, intense pain projecting to the inguinal region and nausea. It usually occurs in adolescent males and requires urgent surgical treatment to prevent complete necrosis of the testis. After 12 hours, the testis is usually irreversibly damaged and it is necessary to remove it. Orchidectomy is a surgical removal of the testis.  CLINICAL CORRELATION In a suspected testicular tumor, a diagnostic biopsy is contraindicated due to the risk of dissemination of tumour cells in the layers of the scrotum.  EPIDIDYMIS Epididymis is a highly convoluted duct. Attached to the posterior margin of the testis and inferiorly to the scrotum. Tail of the epididymis continues as the ductus deferens. Spermatozoa spend 10–12 of their total 72 days of maturation within the epididymis. Serves as a reservoir of spermatozoa, where they mature and gain the capacity to move and fertilise the ovum. Provides nutrition for the spermatozoa. *If uncoiled, the ductules of the epididymis would reach a length of six meters.  EXTERNAL STRUCTURE OF THE EPIDIDYMIS 1. Head (caput) – cranial part of the head of the epididymis is formed by the efferent ductules 2. Body (corpus) – formed by the convoluted duct of the epididymis 3. Tail (cauda) – caudal part of the epididymis; connects to the ductus deferens 4. Sinus – peritoneal fold; visceral layer of the tunica vaginalis between the testis and epididymis.  SUPPORTING LIGAMENTS OF THE EPIDIDYMIS 5. Superior ligament of epididymis (l. epididymidis superius) – connects the upper pole of the testis to the epididymis 6. Inferior ligament of epididymis (l. epididymidis inferius) – connects the lower pole of the testis to the epididymis 7. Scrotal ligament (l. scrotale) – connects the epididymis and testis to the caudal aspect of the scrotum – a remnant of the gubernaculum testis.  DUCTS AND LOBULES 1. Efferent ductules (ductuli eferentes) 2. Lobules of epididymis (lobuli epididymidis) 3. Duct of epididymis (ductus epididymidis) 4. Ductus/vas deferens  VASCULAR SUPPLY OF THE EPIDIDYMIS Arterial supply: testicular artery (from the abdominal aorta) Venous drainage: pampiniform plexus (to the testicular veins → to IVC on the right side and to the left renal vein on the left side) Lymphatic drainage: lumbar nodes.  DUCTUS DEFERENS A tubular organ that transports spermatozoa from the epididymis to the prostatic urethra by peristaltic contractions. It passes from the scrotum through the spermatic cord and inguinal canal into the lesser pelvis, where it crosses the ureter and enters the prostate.  PARTS OF DUCTUS DEFERENS 1. Scrotal part – located in the scrotum; continuous with the duct of the epididymis 2. Funicular part – located in the spermatic cord (funiculus spermaticus) 3. Inguinal part – located in the inguinal canal 4. Pelvic part – courses through the lesser pelvis, close to the urinary bladder and fuses with the excretory duct of the seminal vesicle External iliac vessels (a, v) – pass posteriorly to the ductus deferens Ureter – runs beneath the ductus deferens in close proximity to the fundus of the urinary bladder  PARTS OF DUCTUS DEFERENS 5. Ampulla of ductus deferens – dilated, most distal segment of the ductus deferens 6. Ejaculatory duct (ductus ejaculatorius) – a common duct formed by the union of the ductus deferens with excretory duct of the seminal vesicle – enters the prostate and joins the prostatic urethra at the seminal colliculus.  SPERMATIC CORD – FUNICULUS SPERMATICUS A tough rope-like structure that contains ductus deferens and several vessels and nerves. It courses from the scrotum to the inguinal canal. Venous pampiniform plexus lowers the temperature inside the spermatic cord, which is necessary for the proper maturation of spermatozoa. Layers of the abdominal wall continue over the spermatic cord and the scrotum, forming their coverings. Layers and content of the spermatic cord are mentioned in the lecture ‘Inguinal canal’.  SEMINAL GLANDS – GLANDULAE VESICULOSAE Seminal glands are located behind the urinary bladder above the prostate. Each seminal gland is a simple tubular gland, composed of a single duct that has multiple convolutions. Seminal glands produce 50–80 % of the ejaculate. Excretory duct of the seminal gland joins the ductus deferens to form the ejaculatory duct that empties into the urethra.  SEMINAL GLAND AND ITS DUCTS 1. Seminal gland 2. Excretory duct – a duct of the seminal gland joining the ductus deferens 3. Ejaculatory duct – a common duct formed by the union of the excretory duct and ductus deferens Regional anatomy 4. Posterior wall of the urinary bladder lies anteriorly 5. Rectovesical pouch of the peritoneal cavity is located posteriorly 6. Ampulla of the ductus deferens is situated medially 7. Prostate is found caudally.  BULBOURETHRAL GLANDS – GLANDULAE BULBOURETHRALES Located on the inferior surface of the deep transverse perineal muscle; empty into the ampulla urethrae Produce a viscous liquid that lubricates the urethra during ejaculation. Regional anatomy: 1. Bulbo-urethral gland 2. Superiorly: gland lies on the inferior surface of the deep transverse perineal muscle 3. Anteriorly: duct enters the ampulla urethrae 4. Inferiorly: bulb of the penis is located under the glands.  PROSTATE – PROSTATA Prostate is the largest male genital gland. Produces 30% of ejaculate fluid. Located subperitoneally, inferior to the urinary bladder. Urethra courses through the prostate along with the paired ejaculatory ducts, the common duct for the epididymis and the seminal glands.  PROSTATE – PROSTATA 1. Base of prostate – broad cranial part around the neck of the urinary bladder 2. Apex of prostate – tip of prostate, points towards the pelvic floor 3. Prostatic urethra – segment of the urethra coursing through the prostate 4. Anterior surface – faces the pubic symphysis, is attached to the pubic symphsis by the puboprostaticus muscle and puboprostatic ligaments 5. Posterior surface – posterior surface facing the rectum 6. Right and left inferolateral surfaces - lateral surfaces facing the pelvic floor 7. Right, left and middle lobes of the prostate - three lobes of the prostate.  REGIONAL ANATOMY OF PROSTATE 8. Cranially – neck of the urinary bladder, embedded in the base of the prostate 9. Dorso-cranially – seminal glands laterally and ductus deferens medially 10. Centrally – urethra 11. Dorsally – rectum behind the rectovesical septum 12. Caudally – apex of the prostate is embedded in the pelvic floor.  VASCULAR ANATOMY OF THE PROSTATE Arterial supply: prostatic branches of the inferior vesical artery and middle rectal artery Venous drainage: prostatic venous plexus and vesical venous plexus Lymphatic drainage: internal and external iliac nodes and sacral nodes.  CLINICAL CORRELATION Per rectum palpation of the prostate is a standard part of the clinical examination, performed by palpating the prostate through the anterior wall of the rectum.  CLINICAL CORRELATION Metastatic prostate cancer Involvement of lymph nodes outside the true pelvis Or spread to nonnodal regions Most common site: bone, especially the vertebrae Less common sites: lungs, liver, and adrenal glands After transurethral resection of the prostate (TURP) for benign hyperplasia of the prostate, the neck of the urinary bladder remains open during ejaculation. This results in retrograde flow of semen into the urinary bladder, causing the so called “dry ejaculation”.  SCROTUM Sac located on the outside of the body, which contains the testis and epididymis. Temperature inside the scrotum is 2–4 degrees lower than core body temperature → ensures optimal spermatogenesis. Contraction of the cremaster muscle pulls scrotum upwards, towards the perineum.  EXTERNAL STRUCTURE OF THE SCROTUM Septum of scrotum (septum scroti) – septum composed of CT that separates the scrotum into two independent cavities, each containing one testis. Raphe of scrotum (raphe scroti) – seam-like line in the place where the genital (labioscrotal) swellings merged during development, right over the septum of the scrotum; continues ventrally as the raphe of the penis and dorsally as the perineal raphe Scrotal ligament (ligamentum scrotale) – remnant of the gubernaculum, a cord of CT attaching the lower pole of the testis and tail of the epididymis to the floor of the scrotum  LAYERS OF THE SCROTUM 8. Vaginal cavity of testis (cavitas vaginalis testis) – serous cavity between the two layers of the tunica vaginalis LAYERS OF THE SCROTUM  PENIS Functions: urination and release of semen Structure: primarily composed of erectile tissue, blood vessels, nerves, and CT. The core of the penis contains three erectile tissues, namely the two corpora cavernosa and the corpus spongiosum.  STRUCTURE OF THE PENIS 1. Root of penis (radix penis) – composed of two crura and the bulb 2. Crura of penis (crura penis) – paired internal part of the corpora cavernosa – attaches to the phalic crest of the inferior pubic ramus and to the pubic symphysis 3. Bulb of penis (bulbus penis) – unpaired dilated part of the corpus spongiosum underneath the perineum 4. Body of penis (corpus penis) – external part of the penis, composed of three erectile bodies 5. Glans penis – most distal segment of the corpus spongiosum, the location of the external urethral orifice.  GLANS PENIS COMPONENTS 5.1. Corona of glans –dilated rim of the glans facing the body of the penis 5.2 Neck of glans – groove separating the glans from the body of the penis 5.3 External urethral orifice – the most distal part at the tip of the glans 5.4 Foreskin / prepuce – skin fold of the body of the penis that can be pulled over the glans to a variable extent 5.5 Frenulum – ventrally located skin crease – a transition between the skin of the glans and the skin of the prepuce 5.6 Preputial glands / Tyson’s glands – small smegma-producing glands at the inner margin of the foreskin.  LIGAMENTS OF THE PENIS Fundiform ligament: it springs from the lower part of the linea alba and splits into two lamellae, which enclose the proximal part of the body of penis and then unite on its urethral aspect with the septum of scrotum. Suspensory ligament: deep to the fundiform ligament and triangular in shape. Its narrow upper end is attached in front of the pubic symphysis and broad lower part blends with Buck’s fascia (fascia of penis) on either side of the body of penis.  VASCULAR SUPPLY Arterial supply: internal pudendal artery 7. Dorsal artery of penis – supplies the skin and glans of the penis and the foreskin 8. Deep artery of penis – inside the corpus cavernosum, gives off the helicine arteries as its branches 9. Artery of bulb of penis – inside the bulb of the penis 10. Urethral artery – inside the corpus spongiosum.  URETHRA MASCULINA – MALE URETHRA Length of the male urethra is about 20 cm Parts: 1. Pars intramuralis – runs through the neck of the urinary bladder 2. Pars prostatica – runs through prostate 3. Pars intermedia (pars membranacea, diaphragmatica) – runs through the muscle tissue of the pelvic and urogenital floor 4. Pars spongiosa – runs in the corpus spongiosum of urethra (bulbourethral glands end here) 4.1 Fossa navicularis – terminal section in the glans of the penis 5. Ostium urethrae externum – outer ostium of the urethra CURVATURES AND SPHINCTERS OF THE MALE URETHRA Curvatures 7. Subpubic curvature – superior-facing concavity at the transition of the membranous and spongy urethra, impossible to straighten 8. Prepubic curvature – inferior-facing concavity of the spongy urethra, straightens during erection Sphincters 9. Internal urethral sphincter – weak smooth muscle sphincter 10. External urethral sphincter – strong striated muscle.  CONSTRICTED AND DILATED SEGMENTS Constricted segments 1. Intramural part 2. Membranous urethra 3. Spongy urethra 4. External urethral orifice Dilated segments 5. Prostatic urethra 6. Ampulla urethrae 7. Navicular fossa  CLINICAL CORRELATION Compared to the female urethra, the male urethra is longer and narrower and therefore less prone to infections. However, due to its course, these infections tend to have a worse clinical manifestation.  CLINICAL CORRELATION Nitric oxide (NO) relaxes vascular smooth muscle. Drugs for erectile dysfunction, such as sildenafil-Viagra, increase the concentration of NO in the vascular beds of the erectile bodies. REFERENCES