Lecture 19-20 Male Flashcards
External and internal genitalia both develop from common embryological primordium, true or false?
False
Where do the indifferent gonads develop?
Retroperitoneally high on the posterior body wall, medial the embryonic kidney or mesonephros
When do permanent kidneys or metanephros take over
At a concurrent time with the gradual degeneration of mesonephros
What are some of the mesonephros recycled as
Male internal genitalia
What do the female internal genitalia develop from?
A separate set of ducts, the paramesophrenic ducts
What influences the differentiation of the testes
The testis determining factor on the Y chromosome.
When does the gubernaculum start to form?
When the mesonephros degenerates
What is the gubernaculum
A strand of connective tissue on either side of the vertebral column
Where does the gubernaculum ultimately extend from
The inferior pole of the ovary or testis through the muscle of the abdominal wall and into the labioscrotal fold
What is the future inguinal canal
The transition of the gubernaculum through the abdominal wall
What enlarges as the mesonephros degenerates
Testis
What is the processus vaginalis
An outfolding of the peritoneum that forms anterior to each gubernaculum and grows into the scrotum with the testes
The processus vaginalis fully closes after the descent of the testes true or false
False, a small cavity is left in front of the testis but direct connection to the peritoneal cavity is lost
What does the inguinal canal contain
Connective tissue
Descended structures: ductus deferens, blood vessels, nerves and lymph vessels
What does the distal end of the gubernaculum remain as
A small structure anchoring the testis to the scrotum
What forms the deep and superficial inguinal ring
The opening in the transversalis fascia and the external oblique
What is another factor thought to be involved in the descend of the testis
Growth of the trunk
The female gubernaculum shortens during the descent of the ovaries true or false?
False, the male gubernaculum does descend during development
What ligaments does the gubernaculum become part of? (3)
Broad, ovarian and round
What is the path of the round ligament?
The uterotubular junction to the side wall of the pelvis and deep inguinal ring. Passes through the inguinal canal and superficial ring to end in mons or labium majora.
What is in the superficial fascia of the scrotum
Cutaneous dartos muscle
What is the role of the dartos muscle
Controlling the loss of heat by wrinkling the skin
What is the dense connective tissue covering the testes
Tunica albuginea
What is the posterior thickening of the tunica albuginea
Mediastinum testis
What does the mediastinum testis contain
Ducts connecting seminiferous tubules with the epididymus
The anterior, medial and lateral testis face what? What is this derived from?
Serous cavity
Processus vaginalis
What does the testis contain? What is it made of? (3)
Seminiferous tubules
Spermatogenic cells, Sertoli cells and Leydig cells
What do the different cells of the testis do?
Spermatogenic - sperm production
Sertoli - support, including binding testosterone
Leydig - testosterone production
What is the epididymus
A single tightly coiled tube on the superior and posterolateral sides of the testis
What is continuous with the epididymus
The ductus deferens
The entire epididymus is adhered to the testis, true or false?
False, only the head and tail is adhered.
The body is separated by the sinus
What are the functions of the epididymus (3)?
Absorbs testicular fluid, phagocytoses dead sperm and matures normal sperm
Where does the spermatic cord extend?
Deep inguinal ring to superior pole of testis
What does the spermatic cord contain?
Ductus deferens, arteries testis and ductus deferens, cremasteric artery, pampiniform plexus of veins, lymph vessels which drain the testes, nerves including sympathetic and parasympathetic fibres from inferior hypogastric plexus
What is the cremasteric artery a branch of? Anastomose with?
Inferior epigastric artery
Testicular artery
Lymph vessels of the spermatic cord drain the scrotum, true or false?
False
What do the pampiniform plexus form?
3-4 veins in the inguinal canal, then 2 veins after the deep inguinal ring
What is the spermatic cord covered by? What is its role
Cremasteric muscle. Elevates testis
What are the two supplies of blood to the testes?
Testicular artery
Cremasteric artery
What is the origin of the testicular artery
Aorta
What does the testicular artery cross?
Psoas major with the ureters
What do the testicular veins drain into?
Right into IVC, left into the renal vein
Where does the ductus deferens travel?
From the tail of the epididymus, through the spermatic cord. At the deep inguinal ring it leaves the spermatic cord and passes medially over external iliac vessels onto lateral wall of pelvis. Crosses superior to ureter at base of bladder where it expands to form a dilation, the ampulla. Joined by duct of seminal vesicle to form ejaculatory duct.
Where are the seminal vesicles
Paired structures between base of bladder and rectum
What is medial to the seminal vesicles.
Ductus deferens
What causes the seminal vesicles to secrete thick alkaline secretion?
Sympathetic stimulation of smooth muscle
What is in the alkaline secretion from the seminal vesicles?
Fructose and coagulating agents
How long are the ejaculatory ducts?
2cm
How do the ejaculatory ducts run?
Anterior-inferiorly into prostate and join prostatic urethra at seminal colliculus.
What does the penis consist of (3)?
Root, body and glans
What do the dorsal corpora cavernosa form after the root of the penis?
Crura
What are the crura covered inferiorly with?
Ischiocavernous muscle
What do the ventral corpus spongiosum form distally and proximally?
Glans and bulb which is attached to the perineal membrae
What wraps around the bulb?
Bulbospongiosis muscle and forms a sphincter
What are the corpora cavernosae and corpus spongiosum covered with?
Dense layer of fibrous tissue - tunica albuginia
What do the tunica albuginia consist of?
Corpora cavernosae - predominantly inextensible collagen + some elastin
Corpus spongiosum - predominantly extensible elastin + some collagen
What does the erectile tissue consist of?
Vascular spaces lined with endothelium
What are the vascular spaces surrounded by?
Bundles of smooth muscle plus many nerve endings and lymph vessels
What bloodflow is predominantly central in the penis and which is predominantly peripheral (adjacent to the tunica albugineae)
Arterial
Venous
What covers the penis
Prepuce - thin skin which forms a fold over glans in uncircumcised males
What are the differences between the superficial fascia and deep fascia?
No fat
Closely adherent to corpora
What does the suspensory ligament of penis span
Pubic symphysis to deep penile fascia of root and body
How is the penis supplied?
Internal pudendal artery which supplies 2x deep dorsal arteries and sends separate branches to each corpora
What is the internal pudendal artery a branch of?
Internal iliac artery
What does the dorsal vein of the penis drain into?
Prostatic plexus and ultimately into the internal iliac vein
What is the dual nerve supply of the penis?
Dorsal nerve and greater and lesser cavernous nerves
What is the dorsal nerve of the penis?
A mixed nerve which is a terminal branch of the pudendal nerve. The pudendal nerve is derived from the sacral plexus
What innervation does the dorsal nerve of penis confer?
Primarily somatosensory but also includes autonomic innervation, mostly sympathetic plus some parasympathetic fibres
What do the sensory branches of the dorsal nerve of the penis innervate?
Skin of shaft and glans
Urethra
What do the somatic branches of the dorsal nerve of the penis innervate? What do the muscles do upon somatic input
Bulbospongiosis, ischiocavernous muscles - the skeletal muscles contract during erection and ejaculation
Perineal muscles - perineal branch of the pudendal nerve causes perineal muscle contraction which assist erection
What are the greater and lesser cavernous nerves derived from?
Prostatic plexus which in turn is the lowest part of the inferior hypogastric plexus
What does damage to the prostatic plexus affect?
Erectile function
What nerves do the plexus in the capsule of the prostate give rise to? What do they consist of?
Cavernous nerves
Mainly parasympathetic fibres + some sensory and sympathetic
Where do the cavernous nerves run?
Through the urogenital diaphragm and supply arteries within the erectile tissue of the corpus cavernosum and corpus spongiosum
What does the lesser cavernous nerve supply?
Corpus spongiosum and urethra
What does the greater cavernous nerve supply?
Erectile tissue of corpus cavernosum. Some filaments also reach the corpus spongiosum
Sympathetic innervation in male genital organs is:
Vasoconstrictor
Parasympathetic innervation in male genital organs is:
Vasodilator
What is the pudendal nerve derived from?
Ventral rami of the 2nd -4th spinal nerves (part of the sacral plexus
Where does the pudendal nerve pass through?
The greater sciatic foramen between piriformis and coccygeus inferior to sciatic nerve
Joins pudendal artery to pass through the lesser sciatic forament between sacrotuberous ligament laterally and obturator internus medially
Enters the pudendal canal - an elongated slit within the obturator fascia
What are branches of the pudendal nerve (3)?
Inferior rectal, perineal, dorsal nerve of the penis
Where does the dorsal nerve of the penis travel
1) Passes along ischiopubic ramus
2) Pierces urogenital diaphragm at the level of the suspensory ligament lateral to the deep penile vein
3) Runs in an undulating course along the length of the dorsal shaft along with the dorsal artery and deep dorsal vein to the glans
Where is the superior hypogastric plexus located?
Anterior to the bifucation of the aorta
What is the superior hypogastric plexus
A continuation of the nerve plexuses in the upper abdomen
What type of innervation does the superior hypogastric plexus contain?
Sympathetic, sensory and some parasympathetic from the pelvic splanchnics.
What do the fibres from the sacral ventral rami also contribute to? (2)
Sciatic nerve and pudendal nerve
How are the superior and inferior hypogastric plexuses connected?
Hypogastric nerve
What fibres do the inferior hypogastric plexuses contain?
Sympathetic, parasympathetic and sensory fibres
What do extensions of the inferior hypogastric plexus supply? (3)
Bladder, rectum, prostrate and penis
What is the inferior hypogastric plexus medial to?
Internal iliac arteries
Where is the prostatic plexus located?
In the capsule of the plexus
What are the two branches of the prostatic plexus and what do they supply?
Superior cavernous nerves
Inferior cavernous nerves
Penis
The erection is under parasympathetic control true or false?
True
Ejaculations are under parasymapthetic control true or false?
False
Detumescence is under sympathetic control true or false?
False
How does an erection occur?
1) Blood flow into mostly central positioned arteries in the erectile tissues of corpora cavernosae and corpus spongiosum
2) Compression of the peripheral venous return vessels against the tunica albuginea
3) Compression is less in the corpus spongiosum which has an elastic tunica albuginea and the erectile tissue is less dilated so the urethra is not compressed
Where does sympathetic stimulation in ejaculation cause contractions in? (6)
smooth muscle in the walls of epidigymus, vas deferens, prostate, bulbourethral glands and pelvic floor muscles
as well as closure of the neck of the bladder
How does ejaculation occur?
Contraction causes expulsion of sperm stored in from epididymus and secretions form the accessory glands which collectively are semen. Sperm stored from the epididymus mixes with semen in the urethra but should not pass into the accessory glands or bladder
How does detumescence occur?
Sympathetic sstimulation causes contraction of arterial muscle which decreases blood flow into the erectile tissue. The lowered pressure also reduces compression of veins facilitating veinous drainage.
