3. Urogenital triangle Flashcards
What features define the pubic outlet?
Pubic symphysis and ischiopubic ramus
to Ischial tuberosity
To sacrotuberous ligament and sacrum and coccyx
Division of the perineum?
Anterior urogenital triangle
Posterior anal triangle
Which vessels pass through the lesser sciatic foramen to reach the perineum?
Pudendal nerve
Internal pudendal vessels
2 divisions of the urogenital triangle?
Divided by the Perineal Membrane into a superior, Deep Pouch and an inferior, Superficial Pouch
Attachments of perineal membrane?
Spans urogenital triangle br
between the ischiopubic rami
Attached to the perineal body in the midline posteriorly
Male deep pouch of the urogenital triangle, inferior and upper boundaries?
Inferior boundary: The thick perineal membrane and its upper boundary
Upper boundary: The thinner fascia covering the superior surface of the external urethral sphincter and the deep transverse perineal muscles. Also contains urethra and bulbo-urethral glands
Contents of deep pouch of urogenital triangle
Superior, deep pouch (or urogenital diaphragm)l, made up of:
- The external urethral sphincter
- Urethra and vagina passing through
- Anterior aperture (opening for the passage of nerves and vessels to the penis or clitoris)
Content of the superficial pouch of the urogenital triangle?
Superficial pouch contents:
- Penis and clitoris
- Labia minora and majora forming the vulva and vaginal vestibule in the female
Genitalia are attached to the _____ membrane and ischiopubic rami. Are bounded inferiorly by ____ fascia.
Genitalia are attached to the perineal membrane and ischiopubic rami. Are bounded inferiorly by superficial fascia.
Change of superficial fascia from abdomen to scrotum?
Abdomen: Scarpa’s
Scrotum: Colles’, perineal fascia
Contents and position of dartos fascia in scrotum and penis?
- Dartos muscle(continuation of Camper’s)
- Colles’ membraneous perineal fascia (continuation of Scarpa’s)
Merged together and indistinct in the penis
Similarities between the anatomy of clitoris and penis?
- Both have 2 crura. Attached to ischiopubic rami and become corpora cavernosa that fill with blood during erection
- One central bulb.
Female: Split as the bulb of vestibule
Male: Becomes the corpus spongiosum that houses the urethra to prevent compression during erection.
Crura and bulb form the root
How many corpora does the penis have?
3 corpora: 2 dorsal cavernosa and the ventral spongiosum
Structural features of penile skin?
Dark, loose, no far
Superficial dartos fascia surrounds whole penis
The skin “doubles back on itself” yo form the prepuce/foreskin that is continuous with the glans at the corona
Structure of the corpora cavernosa?
Divided by a septum that is complete proximally but pectiniform distally (to even out pressures and stay straight)
Each are surrounded by thick tunica albuginea, and deep fascia (Buck’s)
Structure of the corpus spongiosum?
Transmits the urethra and forms the glans as a cap over the corpora cavernosa
Muscles and ligaments of the penis
Ischiocavernosus muscle:
- surrounds each crus
- bulbospongiosus surrounds the bulb
- The muscles support the penis and contribute to erection,
Bulbospongiosus
-compresses the urethra during ejaculation or to expel urine
The supportive ligaments are: -Fundiform
-Triangular (suspensory) from the linea alba and pubic symphysis
What is the foreskin?
Fold of skin, continuous with the glans. With mucous membrane of the urethra
Sebaceous glands form… in the penis
smegma
Where is the frenulum?
Ventrally between the foreskin and the glans
Increased sensation at either side
The skin and glans show a…
Ventral, midline raphe
4 parts of urethta?
Preprostatic
Prostatic
Membraneous
Spongy (containing bulbar and penile)
Features of the membranous part of urethra?
- 1-1.5 cm and narrowest part except for external orifice
- tube of fibro-elastic and smooth muscle, within the striated external sphincter (slow twitch) and pubo-urethral or puboprostatic part of levator ani to resist surges of raised intra-abdominal pressure
Shape and relations of external sphincter?
Inverted pear: With its base on the perineal membrane and its apex pushing up into the prostatic urethra
Features of spongy (bulbar and penile) urethra?
16cm long
Narrowest part of external orifice
Contains: Bulbo-urethral glands + scattered glands esp in navicular fossa (lucuna magna)
Where are the 2 right angle bends of the urethra?
- Between membranous and bulbar urethra
- In the spongy urethra as it becomes pendulous
These must be straightened when passing a catheter
Difference between spongy urethra and external meatus slit in urethra?
Spongy urethra – horizontal slit, but External meatus – vertical slit; the direction change causes spiralling of the stream
What makes up the vulva?
Labia minora
Labia majora: Meet anteriorly to form the mons pubis while posterior they form the posterior commmissure or fourchette
Vestibule between minora, contains vagina and urethral oppening
Prepuce of clitoris (from minora)
What must be done during an episiotomy?
Episiotomy must be backwards and angled laterally, usually to the right, to avoid cutting the anal sphincter
(Procedure to open vaginal opening in a controlled nature)
Structure of clitoris?
The body is essentially just the 2 crura, while the bulb contributes minimally as a little cap over the highly sensitive glans
The bulb of erectile tissue is divided by the vagina and covered by bulbospongiosus that aids the pubovaginalis part of levator ani in its sphincteric affect
Glands and bulbs of the vulva?
Bulbs of the vestibule and the right greater vestibular gland.
Th greater vestibular or Bartholin’s glands may be the site of painful cysts or abscessformation
Epithelium of the urethra?
1. Urothelium until ejaculatory ducts Then... 2. Pseudo stratified columnar Then... 3. Stratified squamous in distal urethra Then... 4. Keratinised at external orifice
Navicular fossa promotes defensive ….
Lactobacilli
The internal pudendal supplies the perineum and in both sexes gives arteries to supply the..
Urethra Posterior 2/3 of the scrotum or labia (anterior via external pudendal from femoral) Cavernous tissue of penis or clitoris Skin of shaft Glans of penis or clitoris
Layers of the penis
- Skin
- fascia
- Superficial dorsal veins (to the external pudendals)
- Buck’s fascia
- Deep dorsal vein (to prostatic plexus –> Internal iliac vein) , Dorsal penile artery, Dorsal nerve of the penis
- 2 x corpus cavernosa (containing deep arteries and veins) and corpus spongiosum (containing the urethra and urethral arteries)
Drainage of penis
Penile skin and foreskin –> SUPERFICIAL DORSAL VEINS –> External pudendals
Glans and shaft –> DEEP DORSAL VEIN –> Prostatic plexus and then internal iliac
Corpus cavernosa–> DEEP VEINS –> Internal pudendal
Internal pudendal inferior to the levator ani recieves scrotal (labial) and penile tributaries
Prostatic and vesical plexuses drain to…
Internal iliac vein
Lymph drainage of : Corpora cavernosa, Corpus spongiosum, Bulb of penis and vestibule, Proximal vagina and Urethra is to....
The internal iliac nodes
Lymph drainage of:
Superficial penis
Scrotum
Labia is to…
Superficial inguinal nodes
Lymph drainage of Glans of penis and clitoris is to..
Deep inguinal (Cloquet) and external iliac nodes
Perineal nerves need to provide somatic motor control of which striated muscles?
External urethral sphincter Anal sphincter Bulbospongiosus Ischio-cavernosus Perinei
Sensation innervation is require for which perineal structures?
Urethra
Glans of penis
Clitoris
Where is somatic, sensation and autonomic sensation derived from in the perineum?
S2,3,4- Pudendal nerves (Somatic)
and
Pelvic plexus (ANS)
Branches given of by pudendal nerve (S2,3,4)
Muscular branches to: Bulbospong, ischiocav and external urethral sphincter
Dorsal nerve of penis:
-Sensory as far as glans
Perineal nerve:
-Gives posterior scrotal (or labial) nerves
Parasympathetics pelvic splanchnics are from..
S2,3,4
Cavernous nerves pass to..
Prostate and urethra Corpus spongiosum Erectile tissue of corpora cavernosa Penis Clitoris
