Male Anatomy Flashcards
Both sexes develop from a different embryological primordium and form similar internal genitalia. True or False?
False. Both sexes develop from a common embryological primordium which forms separately to the internal genitalia.
In what manner do indifferent gonads develop?
Retroperitoneally
Where do indifferent gonads develop?
- High on the posterior body wall
2. Medial to the embryonic kidney or mesonephros
What takes over after the gradual degeneration of mesonephros?
Permanent kidneys or metanephros
What are some of the mesonephric ducts recycled as?
Male internal genitalia
How do female internal genitalia develop?
From a separate set of ducts, the paramesonephric ducts.
What is responsible for testis differentiation during week 6 of development?
Under the influence of a gene on the Y chromosome, the TESTIS DETERMINING FACTOR.
Ovaries develop earlier than testes. True or false?
False. Ovaries develop later.
When does the gubernaculum start to form?
As the mesonephros degenerate in week 8
What is the gubernaculum?
Strand of connective tissue on either side of the vertebral column.
Where does the gubernaculum extend?
From the INFERIOR POLE OF OVARY OR TESTIS through muscle of the ABDOMINAL WALL and into LABIOSCROTAL FOLD.
What does the transition of the gubernaculum through the abdominal wall become in the future?
Inguinal canal
When does the testis enlarge?
When the mesonephros degenerate
Where has the testis moved about 25 weeks later?
From the abdomen into the pelvis.
What happens during the outfolding of the peritoneum?
The processus vaginalis forms anterior to each gubernaculum.
Where does the processus vaginalis grow down into?
The scrotum with the tesits.
The final descent of testes into scrotum is slow. True or false.
False, it is quick.
What occurs once the testes have descended?
The processus vaginalis closes.
Direct connection with peritoneal cavity is lost.
Is the processus vaginalis fully closed?
No. There is a small cavity in front of the testis.
What is the inguinal canal lined with?
Connective tissue
What structures does the inguinal canal contain?
Structure which descended with the testis: ductus deferens, blood vessels, nerves, lymph vessels.
What is the function of the distal end of the gubernaculum?
Small structure anchoring testis to scrotum.
What does the opening in the transversalis fascia become?
Deep inguinal ring
What does the external oblique become?
Superficial ring
The gubernaculum shortens during some stages of descent. True or false.
False. It shortens during all stages of descent.
In females what does the developing gubernaculum become attached to?
Sides of the structures which will form the uterus.
In which directions does the ovaries descend into the pelvis?
They move laterally.
The female gubernaculum does not shorten. True or false?
True.
What does the female gubernaculum become incoportaed into?
The broad ligament as the ovarian ligament and round ligament.
Where does the round ligament run?
From the uterotubuluar junction to the side wall of the pelvis and the deep inguinal ring.
What does the round ligament pass through?
Passes through the inguinal canal and superficial ring to end in mons or labium majora.
What is the scrotum comprised of?
Skin, with cutaneous dartos muscle
Which layer is the scrotum a part of?
Superficial fascia
What is the function of the scrotum?
Muscle controls loss of heat by wrinkling the skin (temperature is important for sperm production)
What is the testes comprised of?
Oval, each covered with dense connective tissue, the tunica albuginea.
What does the tunica albuginea form?
The tunica albuginea thickens posteriorly to form the mediastinum testis
What does the mediastinum testis contain?
Contains ducts connecting seminiferous tubules with epididymus.
What do the anterior, medial and lateral testis face?
A serous cavity dervied from the processus vaginalism
What lines the testes?
Tunica vaginalis
What do the testis contain?
Seminferous tubules with spermatogenic cells and Sertoli cells and Leydig cells - testosterone production.
What is the epididymus?
A single tightly coiled tube
Where does the epididymus lie?
On the superior and posterolateral sides of the testis - continuous with ductus deferens.
Where is the head and tail of the epididymys?
It is adherent to testis.
Where is the body of the epididymus?
Separated from testis by sinus of epididymus
What is the function of the epididymus?
Absorbs testicular fluid, phagocytoses dead sperm, maturation of normal sperm.
Where does the spermatic cord extend from?
Extends from deep inguinal ring to superior pole of testis.
What does the spermatic cord contain?
- Ductus deferens
- Arteries of testis and ductus deferens
- Cremasteric artery
- Pampiniform plexus of veins
- Lymph vessels draining testis but not scrotum
- Nerves (as a plexus on arteries) including sympathetic and parasympathetic fibres from inferior hypogastric plexus
What is the cremasteric artery a branch of and what does it anastomose with?
Branch of the inferior epigastric artery
Anastomoses with testicular artery (near testis)
What does the pampiniform plexus of veins join to form?
3-4 veins in the inguinal canal
Then join to become 2 veins after deep inguinal ring.
What is the spermatic cord covered with? Why?
Cremasteric muscle - elevate testis.
What vessels does the blood supply to the testis and epididymus?
Testicular arteries
Testicular veins
Cremasteric artery
Where are the testicular arteries?
Off aorta just below renal arteries - cross psoas major with ureters.
Where are the testicular veins?
Right into inferior vena cava, left into left renal vein.
What is the ductus deferens?
30-45 cm long with thick muscular wall.
Where does the ductus deferens extend?
- Extends from tail of epididymus, through spermatic cord.
- At 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 from a dilation, the ampulla
- Joined by duct of seminal vesicle to form ejaculatory duct
Where is sperm stored?
Ampulla
What are the seminal vesicles?
Paired structures between base of bladder and rectum
What do the seminal vesicles consist of?
Single tubes 15 cm long coiled down to 5 cm
The ampulla of ductus deferens is lateral to the seminal vesicles. True or false?
False. It lies medial.
What does sympathetic stimulation of smooth muscles in the seminal vesicles do?
Causes secretion of a thick alkaline secretion rich in fructose.
Also includes coagulating agents.
What are the ejaculatory ducts?
2 cm long
Where do the ejaculatory ducts run?
Anterior-inferiorly into prostate and join prostatic urethra at seminal colliculus.
Where is the prostate?
Embedded in pelvic fascia
What is the prostate surrounded by?
Prostatic venous and nerve plexus
Where is the base (superior) prostate attached?
To the neck of the bladder
Where is the apex (inferior) attached?
Urogenital diaphragm
What does the prostate consist of?
Fibrous capsule and a fibromuscular stroma containing a network of branched glands and ducts
How can the prostate be subdivided?
Into either lobes or zones
What are the loves of the prostate?
- 2 lateral lobes
- One median and posterior lobe
- One anterior lobe
Where are the median lobes located?
Posterosuperior (above the utricle and ejaculatory ducts)
The median lobe may bulge into a trigone of the bladder to form the uvula
Where is the posterior love located?
Below the ejaculatory ducts
What is different about the anterior lobe?
Is less glandular and more fibromuscular
What zones are included in the prostate?
- Peripheral zone
- Inner or submucosal zone (sometimes further subdivided into internal and innerost)
- Anterior zone (isthmus)
The anterior zone contains many glands. True or flase.
False. It contains few glands.
What is the prostate anterior to?
Rectal ampulla
What is the prostate inferior to?
Bladder and seminal vesicles.
What are the arteries that supply the prostate?
Internal pidenal, inferior vesical, middle rectal arteries
What are the veins that drain the prostate?
Prostatic venous plexus draining to internal ilic veins
What lymph vessels drain the lymph?
Internal iliac nodes
Where are the bulbourethral glands located?
Located adjacent to membranous urethra in deep perineal “space”/urogenital diaphragm
What is the function of the bulbourethral glands?
Produce mucus
What does the duct of the bulbourethral gland pass through?
Perineal membrane to open into spongy urethra
How are the dorsal and ventral surfaces of the penis determined?
Described when the organ is erect. Consists of root, body, glans
What is the erectile tissue comprised of?
- 2x dorsal corpora cavernosa - paired in body
1. 1x ventral corpus spongiosum
What do the dorsal corpora canvernosa become in the root of the penis?
Separates in the root of the penis to form crura.
What are the crura covered with inferiorly?
Ischiocavernous muscle
What does the ventral corpus spongiosum contain?
Urethra
What does the corpus spongiosum become distally and proximally?
Distally to form glans and proximally to form bulb
What is the bulb attached to?
Perineal membrane
What muscle wraps around the bulb?
Bulbospongiousus muscle (sphincter)
What are the corpora cavernosae and corpus spongiosum covered with?
Dense layer of fibrous tissue called Tunica Albuginia.
What is the part of the tunica albugina around the corpora cavernosae predominantly made of?
Inextensible collagen (plus some elastin)
What is the part of the tunica albugina of the corpus spongiosum predominantly made of?
Extensible elastin (plus 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.
Where is the arterial inflow of the erectile tissue?
Predominantly central
Where is the venous component of erectile tissue?
Predominantly peripheral i.e. adjacent to the tunica albugineae.
What is the penis covered with?
Think skin which forms a fold - prepuce
What does the prepuce cover?
To cover glans in uncircumcised males
Superficial fascia has no fat. True or false.
True
Deep fascia is closely adherent to corpora. True or false.
True
Where is the suspensory ligament of the penis?
Pubic symphysis to deep penile fascia at junction of root and body.
What are the vascular structures of the penis?
- Internal pudendal artery which supplies 2 deep dorsal arteries and sends separate branches to each corpora.
- 1x deep dorsal vein
What branch of does the internal pudendal artery come from?
Branch of internal iliac artery
What does the deep dorsal vein drain into?
Prostatic plexus and ultimately into internal iliac vein.
What are the nerves of the penis?
- Dorsal nerves of the penis
2. Greater and lesser cavernous nerves
What are the dorsal nerves of the penis?
A mixed nerve which is a terminal branch of the pudendal nerve.
What is the pudendal nerve derived from?
Sacral plexus
What is the function of the dorsal nerve of penis?
Primarily somatosensory (sensory and motor) but also includes autonomic innervation, mostly sympathetic plus some parasympathetic fibres.
Describe the sensory functions of the dorsal nerve of the penis.
- Predominantly sensory branches to skin of shaft and flans
2. Sensory fibres to urethra
Describe the somatic functions of the dorsal nerve?
Supply to:
- Bulbospongiosis, ischiocavernous muscles (somatic motor input causes these skeletal muscles to contract during erection and ejaculation)
- Perineal muscles (perineal branch of the pudendal nerve causes perineal muscle contraction which assists erection)
Where is the greater and lesser cavernous nerves derived from?
Prostatic plexus, which in turn is the lowest part of the inferior hypogastric plexus
What can happen if the prostatic plexus is damaged?
May affect erectile function.
What does the plexus in the capsule of prostate give rise to?
Cavernous nerves which consist of mostly parasympathetic fibres plus some sensory and sympathetic fibres..
Where do the cavernous nerves run?
Run through the urogenital diaphragm
What do the cavernous nerves supply?
Supply arteries within the erectile tissue of corpus cavernosum and corpus spongiosum.
What are the structures supplied by the lesser cavernous nerve?
Corpus spongiosum and urethra
What are the structures supplied by the greater cavernous nerve?
- Supply erectile tissue of corpus cavernosum
2. Some filaments also reach erectile tissue of corpus spongiosum,
Sympathetic innervation in male genital organs is vasocontrictor and parasympathetic is vasodilator. True or false.
True.
Where is the pudendal nerve derived from?
Ventral rami of the 2nd (S2) - 4th (S4) spinal nerves (part of the sacral plexus)
What does the pudendal nerve pass through?
- Passes through greater sciatic foramen between piriformis and coccygeus inferior to sciatic nerve
- Joins the internal pudendal artery (a branch of the internal iliac artery), passes through the lesser sciatic foramen between sacrotuberous ligament laterally and obturator internus medially
- Enters pudendal canal - an elongated slit within the obturator fascia (not a patent opening but filled with loose connective tissue)
What are the branches of the pudendal nerve?
- Inferior rectal
- Perineal
- Dorsal nerve of penis
Where does the dorsal nerve of the penis pass?
- Passes along ischiopubic ramus, pierces urogential diaphragm.
- 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 urogential diaphragm?
- At the level of the suspensory ligament
2. Lateral to deep penile vein.
What are the different hypogastric plexuses?
- Superior hypogastric plexus
- Inferior hypogastric plexus
- Prostatic plexus
What is the superior hypogastric plexus a continuation of?
Nerve plexuses in the upper abdomen (celiac, superior and inferior mesenteries)
Where is the superior hypogastric plexus located?
Anterior to bifucation of aorta.
What fibres does the superior hypogastric contain?
Sympathetic and sensory fibres and some parasympathetic from pelvic splanchnics
Pelvic splanchnic nerves are parasympathetic whereas thoracic and lumbar splanchnics are sympathetic. True or false.
True.
What do the fibres from the sacral ventral rami contribute to?
Other nerves e.g. sciatic nerve, pudendal nerve
What is the inferior hypogastric plexus connected to?
Superior hypogastric plexus by hypogastric nerves
Where is the inferior hypogastric plexus located?
Medial to internal iliac artery.
What fibres does the inferior hypogastric plexus contain?
Sympathetic, parasympathetic and sensory fibres.
What is the inferior hypogastric plexus an extension of?
Inferior hypogastric plexus
What does the inferior hypogastric plexus supply?
- Bladder
- Rectum
- Prostate and penis
Where is the prostatic plexus located?
Located in the capsule of the prostate
What branches does the prostatic plexus contain?
Superior and inferior cavernous nerves which supply the penis
What controls erection?
Parasympatetic system.
Where does the blood flow during an erection?
Blood flows into the mostly central positioned artiers in the erectile tissues of corpora cavernosae and corpus spongiosum
What does the blood flow during an erection compress?
- Peripheral venous return vessels against the tunica albugianeae.
Compression in the corpus spongiosum is less than the compression in the peripheral venous return vessels. Why?
True. Corpus spongiosum has an elastic tunica albuginea which means that the erectile tissue is less dilated and so the urethra is not compressed.
What controls ejactulaion.
Sympathetic system
Describe the process of ejaculation.
- Sympathetic stimulation results in contractions of smooth muscle walls of epididymus, vas deferens, prostate bulbourethral glands and pelvic floor msucles as well as closure of neck of bladder.
- Contraction causes expulsion of sperm stored in from epididymus and secretions from the accesory glands which colletively are sperm
- Sperm stored from the epididymus mixes with semen in the urethra but should not pass into the accesory glands or bladder
What is detumescence?
Termination of erection
What controls detumescence?
Sympathetic control
Describe the process of detumescence.
Sympatehtic control causes contraction of arterial msucle which decreases blood flow into the erectile tissue. The lowered pressure also reduced compression of veins faciliating venous drainage.
