Exam V: Perineum Flashcards Preview

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Flashcards in Exam V: Perineum Deck (32):

Pelvic Diaphragm Borders

Diamond shaped region with same boundaries as pelvic outlet

Floor is skin & fascia

Roof is pelvic diaphragm and fascia

Region between legs externally and shallow compartment internally

Divided into anterior urogenital triangle and posterior anal triangle
The pelvic diaphragm and urogenital hiatus are superior boundaries to the perineum


Deep Perineal Pouch

Deep perineal pouch: perineal membrane + urogenital diaphragm: reinforces pelvic diaphragm and supports pelvic viscera

Perineal membrane is the superior boundary for deep perineal pouch which is analogous with the pelvic diaphragm


Contents of the Perineal Pouches

Superficial Pouch:
2 Erectile Bodies
corpus cavernosum/crus
corpus spongiosum/bulb

3 Muscles:
superficial transverse perineal m.

Deep Pouch Muscles:
deep transverse perineal
external urethral sphincter (M/F)
urethrovaginal sphincter (F)
compressor urethrae (F/M?)


Perineal Body/Central Tendon

Small mass of fibromuscular tissue, larger in females

Fascia attaching to perineal body:
Colle’s fascia (superficial perineal fascia)
Perineal membrane
Superior fascia of the UGD
Deep perineal fascia

Muscles attaching to perineal body:
Superf/Deep trans. perineals
External anal sphincter
Portion of Levator ani



Mediolateral: permits wide expansion but may involve the ischo-anal fossa

Median: damages the perineal body

Muscles attached to perineal body are cut
If levator ani is damaged: prolapse of uterus
Innervation damaged: incontinence
Even if you sew it too tight the muscle won’t be able to relax enough


Ischoanal Fossa

Lies between skin and pelvic diaphragm

Allows expansion during child birth and defecation

Divided into posterior and anterior recesses


Superficial Perineal Fascia

2 Layers of Superficial Perineal Fascia
subcutaneous, fatty superficial layer
membranous, deep layer = Colle’s fascia

Colle’s Fascia: continuous with Scarpa’s fascia
Attaches to:
--fascia lata in thigh
--pubic arch
--posterior border of perineal membrane
Extends over penis/scrotum as dartos fascia (tunic- contains smooth muscle)


Deep Layer of Perineal Fascia

Continuous with fascia of external oblique and external spermatic fascia

Forms tubular investment for shaft of penis as far as glans and proximally surrounds crura and bulb (Buck’s fascia)

Surrounds crura and bulb, covers superficial perineal muscles; in perineum, termed external perineal fascia or Gallaudet’s fascia. Attaches to inferior fascia of UGD

Forms suspensory ligament of penis/clitoris


Rupture of Male Urethra

1. Lacerations of spongy urethra + Buck's fascia intact = urine spreads along the shaft of the penis

2. Lacerations of spongy urethra + Buck's fascia torn = urine leaks into the superficial pouch/scrotum, along the shaft of the penis, superficial to Buck's fascia, and along the anterior abdominal wall deep to Scarpa's fascia in abdomen

3. Above UGD: urine leaks into pelvic cavity below peritoneum

4. Ruptured Membranous Urethra: deep perineal space

5. Ruptured spongy urethra, Buck's fascia, and Colle's fascia = urine leaks to same areas as #2 + pelvic cavity


Male External Genitalia

Corpus spongiosum: contains urethra

Bulb – enlarged region at base of corpora spongiosum, penetrated by urethra

Glans – expanded, cap-like portion, has external urethral orifice

Corona – edge of glans, extends backwards over corpora cavernosa

Crura- legs of corpus cavernosa, attached to the ischiopubic ramus


Male Perineal Muscles

Bulbospongious: Functions to empty urethra, compress deep dorsal vein and erectile tissue, contracts during ejaculation

Ischiocavernosus: Moves blood from caudal to rostral, compresses deep dorsal vein

Superficial transverse perineal: stabilizes perineal body


Male Perineal Ligaments

Suspensory ligament – deep fascia, arises from pubic symphysis, forms sling attached to deep fascia of penis (Buck’s fascia)

Fundiform ligament – subcutaneous tissue that arises from linea alba, SUPERIOR to pubic symphysis, also forms sling (Scarpa’s fascia derived)


Peyronie’s Disease

fibromatosis of TUNICA ALBUGINEA and Buck’s fascia
Connective tissue overgrowth in hands causing excessive contraction – cut out extra tissue
This happens in penis, fibrous plaques in penis causing painful bend during erection ONLY



Look like bag of worms that feel heavy/sand like
Blood from the paminiform plexus isn’t being drained

Left side more often because it drains into the left renal vein sometimes impinged by the superior mesenteric artery and not so much on the right side because just has to drain into the IVC


Female Perineum

Vulva – includes:
1. Mons pubis- collection of subcutaneous fat in front of pubic symphysis
2. Labia majora-fat filled prominence, contain termination of round ligament of uterus
3. Labia minora- folds of skin devoid of fat and hair
4. Clitoris- prepuce, frenulum
5. Vestibule- space between the labia minora; bulb of the vestibule deep to labium minora
6. Greater vestibular glands

sensory & erectile tissue of arousal and intercourse
direct flow of urine
prevent entry of foreign material into urogenital tract


Female External Genitalia

Vestibular bulb – Homologue of bulb of penis and adjoining corpus spongiosum, two bulbs join each other and join the clitoris; serves as vaginal sphincter and aids in erection of clitoris

Corpora Cavernosa – join together to form clitoris, ischiocavernosus helps to maintain erection of clitoris by compressing veins

Clitoris – consists mainly of erectile tissue, crus, body and glans which is highly innervated

Greater vestibular glands (Bartholin’s gland)s) -- secrete mucous, homologues to male Cowper’s glands

Lesser Vestibular glands


Female Perineal Muscles

Superficial transverse perineal- running from 2 ischial tuberosities

Perineal body – when the perineal body has been torn and not properly repaired, contraction of the anterior fibers of the levator ani increase (instead of decreasing) the normal gap in the pelvic floor, this can lead to prolapse of the uterus, ovary or rectum


Pudendal Artery

Internal pudendal artery supplies the perineum:
1. Dorsal arteries of the clitoris/penis – superficial, either side of deep dorsal vein
2. Deep arteries – inside corpora cavernosa, involved in erection, also supply crura
3. Artery of bulb – supplies corpora spongiosum & bulbourethral glands
4. Posterior labial artery/Posterior Scrotal

External pudendal (deep/superficial): supplies labia majora and scrotal skin


Pudendal Branches

1. Inferior rectal nerve: in ischioanal fossae, innervates ext. anal sphincter, some levator ani, and sensory
to skin of anal triangle

2. Perineal nerve: runs into UG triangle, motor supply to skeletal mm. in superficial/deep perineal
pouches, sensory via post. scrotal nerve (M) and post. labial nerve (F)

3. Dorsal nerve of Penis/Clitoris: enters deep pouch, sensory to penis/clitoris


Arteries of Erection

deep arteries & branches of dorsal artery of internal pudendal -- bring blood to cavernous spaces

some of these vessels go directly into cavernous spaces

some vessels form helical arteries, most abundant in corpora cavernosa

Tissue surrounding it close off vein so blood within arteries cannot go anywhere until erectile tissue relaxes


Venous Drainage of Penis/Clitoris

Superficial dorsal vein: drain skin/prepuce penis/clitoris -- dump into superficial external pudendal vv.
External. pudendal vv. drain anterior labia majora/scrotum into femoral vv.

Deep dorsal vein lies beneath Buck’s fascia, superficial to tunica albuginea. -- Drains glans & corpora cavernosa; Passes between two parts of suspensory ligament of penis/clitoris, dumps into prostatic plexus in males & bladder venous plexus in females.



Maintaining erection more than 4 hours – detrimental
Sickle cell anemia RBCs get stuck there – when no longer able to supply O2, necrosis of tissues
Too much Viagra


Penile Fracture

Fracture the penis – during erection, the tunica albuginea can be fracture and blood leak out and hematomas occur – bad
Cast that you must wear until healed



inability to get an erection

can arise from traumatic injury to pudendal nerve or pelvic splanchnic nerves

spinal cord trauma

Viagra – affects the relaxation of smooth muscle in corpora cavernosa

Nervous problems (innervation), blood might not be able to get there (arterial problem), or might not be able to stay (venous problem)



Cyst within the vestibule indicative of gonorrhea and should be treated immediately


Anal Canal

Begins at ampulla
Terminates as anus
Surrounded by internal and external sphincters
Pectinate line demarcates visceral vs. somatic innervation

Pectineal line- end of anal columns, sinuses, and valves
Anocutaneous/White line – where the anal canal becomes keratinized stratified squamous skin


Anal Columns and Crypts

Anal columns – contain terminal branches of superior rectal artery/vein and anastomoses with middle rectal A/V

Anal crypts – ducts of glands, may form cysts or become infected (abscess


Internal Anal Sphincter

Anal canal surrounded by rings of muscle, sphincters, (internal and external parts). Sphincter tone keeps anal canal closed; during defecation, sphincters relax.

Anorectal sling = puborectalis+ internal & external sphincters

Internal sphincter: involuntary and stimulated by sympathetics via hypogastric plexus; inhibited by parasympathetics via pelvic splanchnic nerve

White line of Hilton – below this line, anus lined with true skin (somatic)


External Anal Sphincter

External anal sphincter
Voluntary; inf. rectal n. off pudendal
surrounds entire length of anal canal
3 parts, skeletal muscle attached to perineal body

1. Subcutaneous – surrounds lower part of anal canal, sits beneath skin at anal orifice, subcutaneous at white line in anal canal

2. Superficial – arises from coccyx

3. Deep part – fused with puborectalis


Anal Canal Above and Below Pectinate Line

Above – hindgut
Blood supply: superior rectal, IMA, middle rectal
Venous Drainage: superior rectal veins (portal system)
Lymphatic drainage: internal iliac nodes
Innervation is inferior hypogastric plexus (visceral)

Below –
Blood supply: inferior rectal from internal iliac and middle rectal
Innveration: inferior rectal nerves (somatic)
Lymphatic drainage: superior inguinal nodes
Venous drainage is inferior rectal veins (caval system)



1. Feces passes from sigmoid colon to rectal ampulla

2. Filling of rectal ampulla stimulates stretch receptors (VA, CNS sensation of filling)

3. Defection can occur consciously

4. Relax puborectal sling, increase intraabdominal pressure

5. Stimulate stretch receptors in anorectal canal  relax internal anal sphincter

6. Relaxation of external sphincter, contraction of anorectal canal smooth muscle and elevation of anal canal by levator ani causes ejection of stool


Defective Defecation

Disruption of reflex arcs that control defecation results in incontinence.

Infants have a weak external anal sphincter.

Commonly there is weakening of external sphincter with age; as a result diarrhea can cause incontinence.

Inferior rectal nerve damage