8. Pelvis and Perineum Flashcards
Where is the perineum and what does it contain?
What regions does it have?
Describe the nerve and blood supply of the perineum.
Most inferior region of pelvic outlet, separated from pelvic cavity by pelvic floor. Contains structures supporting urinary, genital and gastrointestinal viscera.
Urogenital triangle (symphysis pubis, inferior ramus of pubis), dividing line: ischial tuberosities. Anal triangle (sacrotuberous ligament, coccyx)
Pudendal nerve -> inferior rectal nerve, dorsal nerve of penis/clitoris, perineal nerve. Pudendal artery -> inferior rectal, branches to penis, labia and clitoris. Pudendal vein. Travel within pudendal canal.
What are the nerve roots of the pudendal nerve?
Where does the pudendal nerve exit the pelvis?
After passing behind the ischial spine, where does the pudendal nerve enter the perineum?
S2 - S4
Through the greater sciatic foramen
Through the lesser sciatic foramen. Then passes into pudendal canal (formed by fascia overlying obturator internus)
Label A-G
A) pudendal nerve
B) lesser sciatic foramen
C) inferior anal nerve
D) deep perineal nerve
E) superficial perineal nerve
F) posterior scrotal nerve
G) dorsal nerve of the penis
What is a pudendal nerve block?
Which internal iliac branches exit the pelvis?
What are the borders of the anorectal triangle?
What are the contents of the anorectal triangle?
Quick pain relief in child birth - palpate ischial spine and local anasthetic injected inferior to, into pudendal nerve
Superior and inferior gluteal arteries, (internal) pudendal artery -> inferior rectal, perineal, dorsal clitoral/penis
Coccyx, sacrotuberous ligaments and imaginary line between ischial tuberosities.
Anal aperture, EAS muscle, 2 ischioanal fossae (spaces loacted to the anus containing fat and CT)
What are the boundaries of the urogenital triangle?
Describe the superficial fascia of the perineum.
Pubic symphysis, ischiopubic rami and imaginary lines between the ischial tuberosities. Contains additional support layer: perineal membrane.
Fatty Layer (Camper’s): continuous with ischioanal fossa and superficial fascia of thigh
Membraneous Layer (Colles’): continuous with Scarpa’s fascia of anterior abdominal wall
Label A-E
A) ischiopubic ramus
B) obturator foramen
C) pubic symphysis
D) ischial tuberosity
E) perineal membrane
Label A-E
A) Ischioanal fossa
B) obturator internus
C) levator ani
D) pudendal canal
E) Internal and external anal sphincters
What are the yellow, red, green and blue areas showing?
Yellow: deep perineal pouch
Red: perineal membrane
Green: superficial perineal pouch
Blue: deep perineal fascia
Where is the deep perineal pouch and what does it contain?
Where is the superficial perineal pouch and what does it contain?
What is the perineal body?
Superior to perineal membrane, contains external ureathral sphincter and deep transverse perineal muscles. Surrounded by fascia.
Between perineal membrane and Colle’s fascia. Contains erectile tissues and 3 muscles: bulbospongiosus, ischiocavernosus and superfical transverse perineal.
Irregular and fibromuscular mass, junction of urogenital and anorectal triangles, important attachment of: levator ani, bulbospongiosum, superficial and deep transverse perineal muscles, EAS, EUS.
Label A-E
A) levator ani
B) external urinary sphincter
C) in males, Bulbourethral gland (Cowper’s gland) - accessory sexual organ, involved in producing pre-ejaculare
D) perineal membrane
E) deep transverse perineal muscle
Label A-E.
A) Colle’s fascia
B) perineal membrane
C) corpus spongiosum
D) bulb of penis (proximal corpus spongiosum)
E) R and L crura of penis (part of corpus cavernosum)
What are the yellow, red, green and blue parts?
Yellow: perineal body
Red: ischiocavernosus (from ischiopubic rami)
Green: bulbocavernosus
Blue: transverse perineal
What is an episiotomy?
Briefly describe the anatomy of the penis.
Surgical cut made at the opening of the vagina during childbirth, to aid a difficult delivery and prevent uncontrolled tearing of perineum, perineal body and other structures.
2 dorsal corpus cavernosa, 1 ventral corpus spongiosum (expands to form glans penis - tip, contains spongy urethra), prepuce (foreskin - connected to glans by frenulum), deep fascial condensations, ateries = pudendal, nerves = pudendal
What is the bulb and crura?
How does erection happen?
How does ejaculation happen?
Bulb: attached to urogenital diaphragm, transversed by urethra, continues forward - corpus spongiosum. Crura: from ischiopubic rami, attached to pubic arch, lie dorsum of penis, corpus cavernosum. [pic]
Efferent nerve impulses (parasympathetic preganglionic outflow to inferior hypogastric plexus) causes NO release -> vasodilation and engorgement of vessels of corpus cavernosum, veins compressed against fascia reducing outflow from penis, pressure increased by ischiocavernosus and bulbospongiosus.
Sexual excitement (Cowper’s gland stimulated - responsible for pre ejaculate), sympathetic fibres stimulate SM of duct of epididymis, vas deferens, seminal vesicles and prostate, rhythmic contractions of bulbospongiosus, sphincter of bladder contracts (internal, involuntary, prevents retrograde ejaculation)
Label the muscles of the superficial perineal pouch and waht they cover/compress.
A) bulbiospongiousus, covers bulb and corpus spongiosum, compresses uretha and dorsal vein
B) superficial transverse perineal muscles
C) ischiocavernosus, covers and compresses crura
Help keep blood in corpus cavernosum during erection
What do the accessory organs of ejaculation do, and what are they?
What are the functions of external female genitalia? (Vulva)
Secrete fluids into ejaculatory ducts and urethra. Seminal vesicles, prostate gland, bulbourethral glands (Cowper’s glands) [pic]
Sensory tissue during intercourse, assist in micturition, barrier to infection
Label A-D
A) prepuce of clitoris
B) glans of clitoris
C) opening of greater vestibular (Bartholin’s gland) - secretes mucus into vagina
D) perineal raphe
Label A-F
A) bulbiospongiosus (reduces size of vaginal orifice, compresses dorsal vein of clitoris, fused in middle in male but not in female)
B) ischiocavernosus (assists clitoral erection)
C) superfical transverse perineal (same as in male)
D) Bartholin’s gland
E) bulb of vestibule
F) clitoris
Explain this pathology.
Bartholin’s cyst. Duct from Bartholin’s gland becomes blocked, causes swelling of gland (cyst), can become infected, may need surgical drainage
