Perineum Flashcards
Boundaries of the Perineum
ANTERIOR: Pubic arch
LATERAL BOUNDARY: Pubic/Ischial rami, ischial tuberosity, sacrotuberous ligament
POSTERIOR BOUNDARY: sacrum and coccyx
ROOF: Pelvic diaphragm
Where is the anal triangle
Posterior to a line connecting the ischial tuberosities
The 2 general components of the Anal Triangle
Anal Canal
Anal Sphincters
Anal Canal
Continuation of rectum beyond the puborectalism
Arterial supply/Venous drainage of the Anal Canal
Above pectinate line: Superior Rectal Artery/vein
Below pectinate line: Inferior Rectal Artery/vein
Innervation of the Anal Canal
Autonomic: inferior hypogastric plexus
Somatic: inferior rectal nerve
How many Anal Sphincters?
2 (Internal and External)
Internal Anal Sphincter
Thickened lower end of the inner circular muscle of the rectum.
- SMOOTH MUSCLE
- A weak sphincter which is not competent acting alone
- INNERVATION: inferior hypogastric plexus
External Anal Sphincter (components and innervation)
(1) Subcutaneous: complete circle just deep to skin
(2) Superficial: attached posteriorly to coccyx, anteriorly to the perineal body
(3) Deep: encircles the anal canal and is fused with the puborectalis muscle
SKELETAL MUSCLE
Innervation: Inferior rectal branch of the pudendal nerve.
Ischiorectoral Fossa
A fat filled space lateral to the anal triangle. USED AS DEAD SPACE FOR ANUS TO EXPAND.
Pudendal Canal
Formed by the fascia of obturator internus which splits to enclose the pudendal neurovascular bundle and connect the lesser sciatic foramen to the posterior perineal membrane.
Perineal Body:
Lies at the front of the anal canal.
It is composed of:
- interdigitating fibers of puboprostaticus (pubovaginalis)
- superficial external anal sphincter
- transversus perinei m.
Nerves of the anal canal
Pudenal N.
Inferior Rectal N.
Pudenal nerve divides at the anterior end of the angle triangle to form:
- Dorsal nerve of the penis/clitoris
- Perineal n.
Blood vessels of the Anal Canal
Internal Pudenal Artery and Vein
- main branch of pudenal= Inferior Artery and Vein
- Internal Pudenal gives perineal branch to superficial pouch and continues to deep pouch.
Arteries to the Uterus/ Vagina/ Ovaries
Uterus: Uterine Artery
Vagina: Vaginal Artery
Ovaries: Ovarian Artery
Main sections and attachments of uterus
- Fundus
- Body
- Cervix
- Uterine Tube (Fallopian tube)
- Fimbria
Scarpa’s fascia turns into….?
Where does this happen?
Turns into Colle’s fascia
Occurs in the perineum
Two proper bends for the positioning of the uterus
- Anteflexion
- Anteversion
Urogenital (UG) Triangle
Anterior part of the perineum which holds all of the components of the Penis or Vagina
Perineal Membrane
Forms the base for the penile (clitoral) musculature and the penis (clitoris)
Spaces deep and superficial to the perineal membrane
Deep: Deep pouch
Superficial: Superficial pouch
Contents of the Superficial Perineal Pouch
ROOTS OF PENIS OR CLITORIS:
- Bulb -FOR FEMALES (posterior part of corpus spongiosum)
- Crura (posterior part of corpora cavernosa)
- Blood supply (deep penile A. to crura and artery to the bulb)
MUSCLES:
- Ischiocavernosus m.
- Bulbospongiosus m.
- Superfical Transverse Perinei m.
Ischiocavernosus M.
Contracts to compress venous outflow of the penis
Bulbospongiosus M.
Surrounds the bulb, it acts to expel any remaining urine or semen in the urethra
Main differences between Male and Female UG Triangle
- Female bulb and bulbospongiosus m. are split by the vagina.
- Greater vestibular gland of female found in superficial pouch
- Bulb FOUND IN DEEP POUCH for male
Nerve of the Superficial Perineal Pouch
Perineal Nerve (branch of the PUDENDAL n.)
Perineal Branches into:
- muscular branches
- scrotal/labial branches
Arteries of Superficial Perineal Pouch
Perineal a. (branch of INTERNAL PUDENDAL)
Perineal branches into:
- muscular branches
- scrotal/labial branches
Contents of the Deep Perineal Pouch
- membranous urethra
- Bulbourethral glands (of MALES)
- Sphincter Urethra m.
- Deep transverse perinei m.
Innervation of Deep Perineal Pouch
All muscles receive innervation from the muscular branch of perineal n. from superficial pouch.
Main Arteries of the Deep Perineal Pouch
All branches of the INTERNAL PUDENDAL A.
- Muscular branch
- Artery to the bulb (pierces the perineal membrane to enter the bulb of the penis or clitoris)
- Deep A: Pierces the perineal membrane to reach the corpora cavernosa
- Dorsal A.: pierces the perineal membrane to reach the dorsum of the penis or clitoris
Veins of the Deep Perineal Pouch
Correspond to the arteries exept the dorsal vein is divided into a deep and superficial dorsal vein
SUPERFICIAL: Drains into the superficial external pudendal veins
DEEP: Enter the pelvic cavity and drain into the prostatic plexus of veins
3 main divisions of the Uterus
Fundus, Body, Cervix
Borders of UG Triangle
- Ischial tuberosity/ Ischiopubic ramus
- Perineal membrane
- Pubic Symphsis
Borders of the Anal Triangle
- Sacrotuberous ligament
- Perineal membrane
- Sacrum
In a cross section of the penis, what structures would be viewed superiorly to inferiorly?
- Skin
- Veins/Arteries (Deep artery of penis)
- 2 tubes of Corpora Cavernosa
- 1 Corpus Spongiosum (surrounding the urethra)
Crus
Extensions of the CORPORA CAVERNOSA which are attached to the perineal membrane
