15. Reproductive System Flashcards
Summarise the layers of the scrotum.
From internal to external:
- (Tunica albuginea)
- Tunica vaginalis (visceral and parietal)
- Internal spermatic fascia (continuous with transversalis fascia)
- Cremaster muscle (fascia continuous with internal oblique aponeurosis)
- External spermatic fascia (continuous with external oblique aponeurosis)
- Superficial fascia
- Dartos muscle
What is the spermatic cord?
The testes and epididymis are suspended within the scrotum by the spermatic cord, a tubular structure that passes through the inguinal canal.
What structures are contained within the spermatic cord?
A good mnemonic is Papers Don’t Contribute To A Good Specialist Level:
- P = Pampiniform venous plexus (drains to testicular vein)
- D = Ductus (vas) deferens
- C = Cremasteric artery (from inferior epigastric artery)
- T = Testicular artery (from abdominal aorta)
- A = Artery to vas deferens (from the superior/inferior vesical artery)
- G = Genital branch of genitofemoral nerve
- S = Sympathetic/Parasympathetic nerves
- L = Lymphatics
What is the blood supply and drainage of the testes?
Blood supply:
- Testicular artery from the abdominal aorta.
Blood drainage:
- Each testis is drained by vesicular veins are arranged in a pampiniform venous plexus -> These pass through the inguinal canal that unite to form a single vein
- The left testicular vein drains to the left renal vein, whereas the right testicular vein drains directly into the inferior vena cava.
What must you remember about the venous drainage of the testes?
The left testicular vein drains to the left renal vein, whereas the right testicular vein drains directly into the inferior vena cava.
What are the layers that make up the fascia surrounding the spermatic cord?
During the descent of the testes into the scrotum, the layers of the anterior abdominal wall are dragged along, creating three layers of fascia surrounding the spermatic cord. These layers are, superficial to deep:
- External spermatic fascia -> Formed from external oblique aponeurosis.
- Cremaster fascia -> Containing the cremaster muscle, formed from internal oblique muscle and aponeurosis
- Internal spermatic fascia -> Formed from transversalis fascia.
Describe the parts of the testis and their functions.
- Seminiferous tubules -> Site of spermatazoa production
- Tunica albuginea -> Contains the seminiferous tubules
- Rete testis -> Drain the seminiferous tubules
- Epididymis -> Drains the rete testis
- Tunica vaginalis -> Double-layered serous membrane that covers the testes
- Vasa efferentia -> Connect the rete testis to the epididymis
Describe the path of spermatazoa.
- Seminiferous tubules
- Rete testis
- Vasa efferentia
- Epididymis
- Vas deferens
- Ejaculatory duct (when vas deferens and seminal ducts join)
- Urethra
Where does the vas deferens pass?
- Through the inguinal canal.
- Passes between the ureter posteriorly and the bladder anteriorly, before passing along the posterior surface of the bladder.
What are the parts of the epididymis?
From superior to inferior:
- Head
- Body
- Tail
These become increasingly straight.
Where in the testis are spermatozoa produced?
Seminiferous tubules
What are the vasa efferentia?
The ducts that connect the rete testis to the epididymis.
Where are spermatozoa stored?
In the epididymis.
What is the ampulla of the vas deferens?
An enlargement of the vas deferens at the fundus of the bladder which acts as a reservoir for sperm.
Where do the products of the prostate gland and seminal vesicles join?
- Vas deferens joins with the seminal vesicles just before the prostate.
- This forms the ejaculatory ducts.
- They pass through the prostate, and open into the urethra.
What are the seminal vesicles?
- Glands that lie behind the urinary bladder, near the prostate.
- They secrete a fluid that is high in fructose and contributes to the semen.
- The seminal vesicles contribute around 2/3rds of the total volume of semen.
Describe the structural regions of the prostate.
The prostate may be divided into a left and right lobe, separated by a superficial median furrow (or groove) on its posterior surface.
What are the different histological zones of the prostate?
- Central zone -> Surrounds the ejaculatory ducts, accounting for 25% of the prostate volume.
- Transition zone -> Located anterolateral to the proximal urethra. The site in which benign prostatic hyperplasia occurs.
- Peripheral zone -> Surrounds the more distal prostatic urethra at the apex of the prostate, accounting for around 70% of the prostate volume. The site in which prostate cancer typically occurs.
What is the function of the prostate gland in reproduction?
Produces and secretes an alkaline fluid containing simple sugars and proteolytic enzymes that contributes to 30% of the volume of semen.
Describe the structure of the penis.
- The penis is made up of three columns of tissue:
- Two corpora cavernosa -> Lying adjacent to each other on the dorsum aspect
- Corpus spongiosum -> On the ventral aspect, housing the urethra
- The corpus spongiosum is surrounded by striated muscle called the bulbospongiosus.
- The glans penis, forming the distal end of the penis, surrounds the urinary meatus and is surrounded by the prepuce (foreskin).
What are the main muscles involved in the penis? What is their function?
- Ischiocavernosus -> Assists in maintenance of the erect penis, as contraction impedes venous return.
- Bulbospongiosus -> Assists with maintenance of erection, but is also important for ejaculation.
Describe how erection occurs.
- Normally, the helicine arteries of the corpora are contracted, so that little blood flows into the penis
- Parasympathetic contribution to erection (cavernous nerves, S2-S4):
- When achieving erection, the helicine arteries of corpora relax
- Somatic contribution to erection (pudendal nerve):
- Contraction of bulbospongiosus and ischiocavernosus impedes venous return
Which nervous system is responsible for emission of semen (not ejaculation!)?
Sympathetic
Which nervous system is responsible for ejaculation of semen?
Somatic
Describe how emission and ejaculation occurs.
Sympathetic nervous system controls emission:
- Sympathetic fibres initiate contraction of smooth muscle of epididymal ducts, ductus deferens, seminal vesicles and prostate in sequence
- Sperm, seminal and prostatic secretions enter prostatic urethra and penile bulb
- Sympathetic stimulation (L1-L2) of internal urethral sphincter prevents ejaculation into bladder
Somatic nervous system controls ejaculation:
- Rhythmic contraction of bulbospongiosus (pudendal nerve S2-S4) moves semen along spongy urethra resulting in ejaculation
What nervous sytem is responsible for erection, emission and ejaculation?
- Erection = Parasympathetic
- Emission = Sympathetic
- Ejaculation = Somatic
A commonly used way to remember the nerves responsible for the male reproductive system reflexes is by using the phrase “Point and Shoot”: Point (erection) = parasympathetic, Shoot (emission) = sympathetic
Summarise the lymphatic drainage of the testes and scrotum.
- Testes -> To the para-aortic nodes
- Scrotum and skin of the perineal region -> To the inguinal nodes
Summarise the innervation of the testes and scrotum contents.
- Sympathetic fibres (T1-L1) -> Supply the testis.
- Somatic fibres (L1 to scrotum):
- Genitofemoral nerve -> To thigh (e.g. cremaster)
- Ilio-inguinal nerve -> To scrotum
- Somatic fibres (S2-S3) -> Supply the rest of the scrotum.
Describe the cremasteric reflex.
- This reflex is triggered by stroking the superomedial aspect of the thigh in a downward direction.
- The normal response is a contraction of the cremaster muscle, pulling up the scrotum and testis on the side stimulated.
- Upper and lower motor neuron lesions can cause an absence of the cremasteric reflex.
- The genitofemoral nerve (L1/L2) is responsible for the afferent and efferent limbs of the reflex arc.
Describe hydrocoele and varicocoele.
Hydrocoele:
- A collection of fluid within the scrotum, between the parietal and visceral layers of the tunica vaginalis.
- This may occur in combination with a patent processus vaginalis and thus communicate with the peritoneal cavity.
- Usually presents as a painless, enlarged scrotum and may resolve spontaneously, but typically needs surgical repair if persisting beyond 12 months.
Varicocoele:
- Anormal dilatation of the testicular veins of the pampiniform venous plexus, caused by reflux of blood into the plexus.
- Varicocoeles are more common on the left due to the angle at which the left testicular vein drains into the left renal vein and lack of effective venous valves.
- Patients describe the scrotum as feeling like a bag of worms, and only rarely do they report pain. Treatment may involve surgical ligation of the veins to prevent abnormal blood flow.
Describe testicular torsion.
The blood supply to the testis can become compromised if the spermatic cord twists within the tunica vaginalis, which can rapidly lead to ischaemic damage and loss of the testis. Testicular torsion is a medical emergency and causes acute scrotal pain and swelling, nausea and vomiting. Treatment is by immediate manual de-torsion followed by surgical fixation of the testis to prevent further episodes of torsion.
Describe mal-descent of testes.
By 28 weeks of gestation, the right and left testes reach the inguinal canals, and by 28-40 weeks, they descend to their final place within the scrotum. An undescended testis is a testis that is absent from the scrotum. This may be due to failure of formation, testicular retraction or failure of descent. Mal-descent may result from an anatomical or hormonal abnormality, although most will descend into the scrotum within the first three months of life.
Where does testicular cancer most commonly spread to?
Testicular cancers most commonly metastasise via lymphatic drainage, usually to the retroperitoneal lymph nodes (para-aortic).
Where does prostate cancer most commonly spread to?
Via venous channels to the IVC and lungs, as well as spreading to the rich venous plexus of the pelvic bones, sacrum and vertebral column.
Describe vasectomy.
Division and ligation of the vas deferens is a surgical method by which male infertility can be achieved for contraceptive purposes. Each vas deferens us divided along its scrotal part, just beneath the superficial inguinal ring. As a result, spermatozoa fail to reach the prostatic urethra and degenerate within the epididymis.
What part of the prostate does prostatic hyperplasia most commonly occur in?
Transitional zone
What part of the prostate does prostatic cancer most commonly occur in?
Peripheral zone
Draw a diagram of the female reproductive system.
What are the ovaries covered by and what is this continuous with?
- Cuboidal epithelium
- Continuous with the peritoneum
Describe the blood supply and drainage of the ovaries.
- Ovarian arteries -> Arising from the abdominal aorta at the level of L2.
- Pampiniform venous plexus drains into ovarian vein -> Drains into the left renal vein on the left and inferior vena cava on the right.
What ligaments does the ovary attach to?
- Broad ligament
- Suspensory ligament -> Suspends the ovary by attaching to lateral abdominal wall
- Ovarian ligament -> Attaches the ovary to the uterus
What are the 4 parts of the Fallopian (uterine) tubes?
- Fimbriae
- Infundibulum
- Ampulla -> Most common site of fertilisation
- Isthmus
What are the 3 main parts of the uterus that the spec mentions?
- Fundus (top of the uterus)
- Body
- Cervix
Label this.
What two important terms describe the alignment of the uterus (relative to the vagina)?
- Anteflexed -> Body of cervix is bent so as to form a slight n shape
- Anteverted -> Cervix is bent forward relative to the axis of the vagina
What are some important relations of the uterine artery?
- Travels via the cardinal ligaments
- Passes anterior to ureter
- Arrives at the lateral fornix of the vagina
What are the fornices of the vagina?
- The fornices are superior recesses of the vagina formed by the protrusion of the cervix into the vaginal vault.
- There is a large posterior fornix and a smaller anterior fornix with two small lateral fornices.
Label this.
Describe the relative positions of the bladder, uterus and rectum in the pelvis.
Draw a sagittal section of the pelvis, showing the bladder, uterus and anus.
What is the broad ligament?
- A double-fold of peritoneum
- It extends from the sides of the uterus medially to the pelvic sidewalls laterally and the pelvic floor inferiorly
What are the different parts of the broad ligament and what does each cover?
- Mesometrium -> Uterus
- Mesosalpinx -> Fallopian tubes
- Mesovarium -> Ovaries
Label this. (Posterior view)
What are the pubocervical and uterosacral ligaments?
- Pubocervical -> Connects the pubic symphysis to the cervix
- Uterosacral -> Connects the uterus to the sacrum
These are mostly supportive ligaments.
What is the perineum? What are the borders?
The perineum is a diamond-shaped region inferior to the pelvic outlet and pelvic floor muscles.
What can the perineum be divided into?
- Urogenital triangle:
- Lies between the pubic symphysis anteriorly, the ischiopubic rami and a line between the ischial tuberosities posteriorly.
- Contains the external genitalia and urethra.
- Has an additional layer of fascia called the perineal membrane, through which the urethra and, in females, the vagina pass.
- Anal triangle:
- Lies between the posterior border of the perineal membrane and body anteriorly and the ischial tuberosities, sacrotuberous ligaments and coccyx posterolaterally.
- Contains the anal canal and the ischioanal fossae (fat filled triangular spaces lateral to the anal canal).
What are the ischiorectal fossae?
Fat-filled triangular spaces lateral to the anal canal.
What are the perineal pouches? What do they contain?
- The space in the perineum just above the perineal membrane is called the deep perineal pouch -> Contains the erectile tissues forming the penis and clitoris
- The space in the perineum below the perineal membrane is called the superficial perineal pouch -> Contains the external urethral sphincter and bulbourethral gland in males.
How do the pudendal nerve and vessels pass through the perineum?
- They pass in the pudenal canal
- This is located in the lateral wall of the ischiorectal fossa
It is shown in orange in the diagram.
Describe the different muscles that assist the functioning of the penis.
- Bulbospongiosus -> Compresses the bulb of the penis and the corpus spongiosum, helping with the emptying of the urethra. Also assists in maintaining penile erection by preventing venous outflow.
- Ischiocavernosus -> Force blood from the crura into the distal parts of the corpus cavernosum and preventing venous outflow, helping with erection.
Draw the structure of the vulva, urethra and clitoris.
What is the vulva vestibule?
The area bounded by the labia minora.
Describe the structure of the clitoris.
- Glans at the tip
- Erectile bodies:
- Two corpora cavernosa, which form from the crura
- Two vestibular bulbs
Describe the structure of the breast.
- 14-18 lactiferous lobules arranged radially around the nipple drain their contents into the lactiferous ducts, which ultimately converge at the nipple-areola complex.
- Areolar glands within this complex secrete an oily substance onto the areola and nipple to keep them protected and lubricated.
- Axillary tail extends upwards and outwards into the axilla.
- The tissue of the breast is supported by the suspensory ligaments, which pass between the deep fascia overlying pectoralis major to the dermis of the skin.
