The perineum Flashcards
Anatomical boundaries
Anterior: Pubic symphysis
Posterior: tip of coccyx
Laterally: inferior pubic rami and sacrotuberous ligament
Roof: Pelvic floor
Base: Skin and fascia
Structural boundaries
Anterior: Mons pubis Inferior: intergluteal cleft Lateral: medial surface of thigh
Contents in males
1- External genitalia (Urethra, scrotum, Penis) 2- Perineal muscles 3- Anal canal
Contents in females
o Female external genitalia o Perineal muscles o Anal canal
Triangles in the perineum
urogenital- anterior anal- posterior Divided by an imaginary line drawn between the ischial tuberosities
what are the boundaries of the urogenital triangle?
o Pubic symphysis o Ischiopubic rami o Theoretical line
what are the boundaries of the anal triangle
o Tip of coccyx o Sacratuberous ligaments o Theoretical line
Layers of the urogenital triangle?
- Deep perineal pouch - Perineal membrane - Superfical perineal pouch - Perineal fascia - Skin
What is the Deep perineal pouch? what does it contain?
o Potential space petween the deep fascia of the pelvix floor and the perineal membrane o It contains part of the urethra, external urethral sphincter o In females : the vagina o In males: the bulbourethral glands and the deep transverse perineal muscles.
What perforates the perineal membrane? what are the clinical implications of this?
the urethra the superficial and deep perineal pouches are fascia-limited spaces transversed by the urethra . They can become infiltrated by urine following traumatic/surgical injury to the urethra
what is the role of the perineal membrane?
site of attachment of the external genitalia
what is the superficial perineal pouch and what does it contain?
oA potential space between the perineal membrane and the superficial perineal fascia
o It contains the erectile tissues that form the penis and clitoris o It contains three muscles – the ischiocavernosus, bulbospongiosus and superficial transverse perineal muscles.
oThe pouch is bounded posteriorly to the perineal body.
what are the contents of the anal triangle
o Anal aperture
o External anal sphincter
o Ischioanal fossae
o Pudendal nerve
What is the perineal body? what does it contain?
o Irregular fibromuscular mass o At junction of urogenital and anal triangles o Contains: skeletal muscles, smooth muscle, fibrous and Elastic fibres
What can happen during childbirth? how can this be prevented?
Perineal body rupture: pelvic floor prolapse Can be prevented by epiostomy. this is a cut into the vaginal mucosa which reduces risk
Muscles of the perineum?
-external anal sphincter -Bulbospongiousus -Ischiocavernosus -transverse perineal -External urethral sphincter
what is the innervation of the muscles of the perineum?
branches of the pudendal nerve
what is the function of the external anal canal?
- Constricts anal canal during peristalsis 2. Resists defaecation 3. Fixes perineal body to pelvic floor
what is the function of the bulbospongiosus?
- Supports the perineal body 2. Assists in erection of clitoris 3. Helps release last bits of semen
what is the function of the ischiocavernosus?
Helps maintain erection of penis/ clitoris
what is the functionn of the transverse perineal muscles?
- Supports/ fixes perineal body 2. Resists intra-abdominal pressure
what is the function of the external urethral sphincter?
compresses urethra to maintain urinary continence
external urethral sphincter vs internal urethral sphincter?
the internal urethral sphincter is Involuntary Innervatio is sympathetic fibres T10-L2
anatomy of muscles
Layers of the urogenital triangle?
