1. Male and Female Urogenital Triangle
Learning Objectives
Perineum 2 Lecture
Male and Female Urogenital Triangle
a. Describe the fascial reflections in the urogenital triangle and the relationship each layer has to the major subdivisions of the triangle (superficial and deep pouches).
b. Understand the relationships between the fascial layers of the anterior abdominal wall with those of the urogenital triangle.
c. Understand the possible routes for spread of fluid which might accumulate in the superficial and deep pouches.
d. Describe the contents of the superficial and deep perineal pouches.
e. Describe the course and distribution of the branches of the pudendal nerve and internal pudendal vessels in the urogenital triangle.
f. Understand the position and importance of the muscles of the urogenital triangle.
g. Describe the fundamental differences and similarities of the male and female urogenital triangles.
h. Describe the role of the autonomic nervous system in sexual arousal.
i. Be able to define vulva, vestibule, prepuce, hymen, episiotomy, circumcision, erection, emission, ejaculation and detumescence.
Pectinate line – the junction of the upper and lower anal canal

2. Plate 360

3. Snell, Fig 23-2

4. Penis and scrotum have been retracted from the field.

5. Fascia of anterior abdominal will is continuous with fascia of urogenital triangle. The name changes once crossing the pubis
Camper’s fascia (fatty)  Dartos fascia (contains smooth muscle)
Scarpa’s fascia  Colles’ fascia
Dartos muscle – the continuation of camper’s fascia around the scrotal sack, which contains smooth muscle that inserts into the skin of the scrotum.
The female doesn’t have darto’s muscle, but rather has fat in this layer that makes the labia majora. It is simply called the superficial fascia.
The distance of the testicles from the abdominal wall are regulated by
Dartos muscle (smooth muscle), continuation of the superficial fascia
Cremaster muscle (striated muscle), that is a continuation of internal abdominal oblique
Colles’ fascia – the continuation of Scarpa’s fascia lining the penis and scrotal sack
Perineal body – thick fibrous tuft just anterior to anal canal.
The UG triangle is physically separated from the anal triangle because Colle’s fascia attaches to the parineal body in the midline and extends out to the ischial pubic rami. Thus blood, pus, etc. cannot move between the UG triangle and anal triangle.
Superficial perineal pouch – the cavity defined as follows:
Floor = Colle’s fascia
Roof = perenial membrane (inferior fascial layer of urogenital diaphragm)
Scrotum and penis are diverticuli of the perineal pouch
Deep perineal pouch – thin cavity define das follows:
Floor = perineal membrane (inferior fascial layer of UG diaphragm)
Roof = superior fascial layer of the UG diaphragm
Tearing the urethra may cause urine to accumulate in the superficial pouch
All skeletal muscles of superficial and deep pouches are innerved by the perineal nerve * * * * * * *
Snell

6. Scarpa’s fascia (cut)
Spermatic cord (cut)
Ischiocavernosus mm – Follow rami of pubic bones. Form sleeves around bodies of erectile tissue. Compresses the crus, thereby allowing it to become engorged with blood but not expanding in diameter, which establishes and maintains erection.
Bulbospongiosus mm – Covers body of erectile tissue on midline and aids in establishing and maintaining erection. Contracting it also forces the last drops of urine out of the pelvis.
Superficial transverse perineal mm – Originates from the inner and forepart of the tuberosity of the ischium and inserts into the perineal body. May help hold perineal body in midline, but has little significance in humans. Atrophies with age
There is no striated muscle in the shaft of the penis. All of these skeletal muscles stop at the point where the penis loses its attachment.
Urethera enters the bulb of the penis
Ischiocavernosus m.
Perineal membrane
Colles’ fascia (cut)
Bulbospongiosus m.
Investing (Gallaudet’s) fascia
Levator ani m.
Gluteus maximus m.
Superficial transverse perineal m.
Plate 361

7. Corpus spongiosum
Corpus cavernosum
Dartos fascia
Erectile tissue is a dense network of vascular sinusoids that are capable of holding a relatively large amount of blood. The erectile tissue can become engorged with arteriole blood.
These parts are responsible for the erection
Crura of penis –Tissue on each side of the penis within the body (L “leg”)
Corpus cavernosum – The continuation of crura into the shaft of the penis (corpus – “body”; cavernousum – “cavernous, rich, dense, sinosidal”)
Bulb of the penis – Tissue along midline of penis after it leaves the base.
Corpus spongiosum – continuation of the bulb in the shaft of the penis. It does not become as tough and rigid as the cavernosum because the urethra passes through is, thus allowing man to ejaculate.
Bulb of penis
Crus of penis
Perineal membrane
Superficial transverse perineal m.
Plate 362

8. Glans penis
Corpus cavernosum
Corpus spongiosum
Corpus cavernosa have a blunt ending at the tip of the penis
Glans of penis – the cap formed by the distal end of the corpus spongiosum. It is suple and soft during erection
Bulb of penis
Perineal membrane
Crus of penis
Superficial transverse perineal m.
Plate 362

9. Superior fascial layer of the UG diaphragm
Urethra
Prostatic
Membranous
Penile
Prostate gland
Sphincter urethrae m.
Bulbourethral gland
Perineal membrane
Bulb of penis
Crus of penis
Deep artery of penis
Urinary bladder sits in the pelvis
Prostate gland sits right on pelvic floor
Three parts to the urethra:
Prostatic part
Membranous
Spongious part of urethra
Corpus cavernosum
Navicular fossa
Plate 365
Glans penis

10. Moore et al; Fig 3.61 Prepuce – the foreskin
Holds 1/3 of nerve endings of penis
During sexual arousal foreskin becomes retracted to around the shaft
No health consequences associated with male leaving foreskin as long as male is taught proper hygiene
Phimosis – Foreskin is so tightly adherent to the glans that it cannot be retracted. Painful during sexual arousal. (gr. “muzzle”)
Paraphimosis – Foreskin is retracted off of the glans and forms a tight ring around junction of glans and penis. Dangerous because compromises blood flow to glans.
Balanitis – inflammation of the glans of the penis; almost always caused by poor hygene.
Smegma – secretions that collect in the glans of the penis.
Moore et al; Fig 3.61

11. Same male during sexual arousal

12. Deep dorsal vein of penis
Superficial dorsal vein of penis
Deep (Buck’s) fascia
Dartos fascia
Dorsal nerve of penis
Dorsal artery of penis
Corpus cavernosum
Tunica albuginea
Midshaft cross section. Top of picture is dorsal part of penis. Two corpa cavernosa and one corpus spongiosum illustrated
Male is never truly in anatomical position unless they are sexually aroused.
There is a connective tissue separation between the two corpus cavernosa
Layers from superficial to deep:
Skin
Dartos layer (with superficial vein). This is a tortuous vein that creates an elevation of the skin It is responsible for draining the subcutaneous tissues of the penis.
Buck’s fascia – deep fascia of the shaft of the penis. It is very thick and tough. It envelops all of the erectile bodies.
Deep dorsal vein of the penis, flanked on either side by dorsal arteries of the penis. These arteries are branches of the internal pudendal artery. Each artery is flanked laterally by the dorsal nerve of the penis, a branch of the pudendal nerve. The deep vein is receiving the outflow of the erectile tissue. Engorging erectile tissue with blood will cause deep dorsal vein of the penis to become compressed due to the overlying fascia.
Deep artery of the penis – artery in the core of each corpus cavernosum, which is responsible for making erections. It is a helicine artery (coiled). Parasypathetic innvervation causes the smooth muscles of these arteries to relax and become uncoiled.
Priapism – erection in excess of four hours. After about four hours the blood will thrombose (clot) and the blood flow through penis will become highly compromised
Priapus – afrodite’s son, who was ugly, and had a huge penis which was always erect.
Deep artery of penis
Corpus spongiosum
Penile urethra
Plate 361

13. Pudendal nerve approaches UG triangle. It has three branches
Superficial rectal
Perineal nerve – innervates all structures in the superficial pouch except the testicles (which migrate into the scrotum), including the skin of the scrotum and muscles of the superficial pouch
Dorsal nerve of the penis – Enters deep pouch and is purely sensory
Dorsal n. of penis
Posterior scrotal n.
Perineal membrane
Perineal n.
Perineal membrane
(cut)
Inferior rectal n.
Pudendal n.
Plate 391

14. Posterior scrotal a.
Branches of the internal pudendal artery
Inferior rectal artery
Perineal artery
The vessel that continues on after the perineal branch is still called the internal pudendal artery.
Perineal a.
Inferior rectal a.
Internal pudendal a.
Plate 385

15. Dorsal artery of penis
Inferior rectal artery, and perineal artery cut
Internal pudendal artery continues on as dorsal deep artery of the penis
Internal pudendal a.
Deep artery of penis
Artery of bulb of penis
Perineal a. (cut)
Plate 385

16. Deep dorsal vein of penis
Perineal membrane fills in subpubic arch.
Superficial transverse perineal muscles are over perineal membrane
Netter leaves the impression of the erectile bodies on the membrane
The paired internal pudendal arteries end as they hit the perineal membrane and each give off two branches:
Dorsal artery of the penis (course just deep to buck’s fascia)
Deep artery of the penis (course through the corpus spongiosum)
Also coming the perineal membrane are
Urethra (membranous part)
Bulbourethral gland (calper’s gland) duct
Dorsal artery of penis
Dorsal nerve of penis
Deep artery of penis
Urethra
Duct of bulbourethral gland
Artery of bulb of penis
Superficial transverse perineal m.
Plate 363

17. Dorsal artery of penis
Deep dorsal vein of penis
Deep artery of penis
Dorsal nerve of penis
Now there is a window in the perineal membrane.
Calper’s gland (bulbourethral gland) – produces alkaline pre-ejaculate component of semen responsible for neutralizing the acidity of the urethra and female reproductive tract. The gland is unique in that it produces its secretion during sexual arousal and does not store it.
Within deep pouch the internal pudendal artery branches into the
Deep artery of the penis
The doral artery of the penis
There is a gap inferior to the pubic symphysis that allows the deep dorsal vein to leave penis into pelvis. That blood will dump into venous plexus around prostate gland.
Superficial dorsal vein dumps into the thigh (not important)
In the female, the deep dorsal vein of the clitoris goes into the bladder of the female.
External urethral sphincter – voluntary muscle in the deep pouch that regulates the flow of urine
The muscles of the deep pouch is supplied by the perineal nerve
Know three branches of the nerve, four branches of the artery
Bulbourethral gland
Internal pudendal a.
Cut perineal artery
Deep transverse perineal m.
Sphincter urethrae m.
Plate 363

18. Dorsal artery of penis
Internal pudendal artery goes from anal triangle and enters deep pouch after it gives of perineal artery. In deep pouch it gives off its two terminal branches, which immediately leave the deep pouch and enter the superficial pouch by piercing the perineal membrane.
Internal pudendal a.
Deep artery of penis
Artery of bulb of penis
Perineal a. (cut)
Plate 385

19. Deep dorsal vein of penis
Membranous part of the urethra is the least dilatable part of the urethra
Muscles that have partial attachment to the perineal body
External anal sphincter
Superfical transverse pernial mm
Bulbos spongiosus m
Deep transverse perineal muscle (forget about this one)
Corpus cavernosum
Penile urethra
Perineal body
Bulbourethral gland
Bulbospongiosus m.
Bulb of penis
Perineal membrane
Glans penis
Plate 346

20. Each crus is coated by an ischial cavernosus muscle
Prostate gland
Membranous urethra
Perineal membrane
Crus of penis
Penile urethra
Ischiocavernosus m.
Bulbospongiosus m.
Colles’ fascia
Bulb of penis
Plate 350