Lecture 23 - The Perineum Flashcards
What is the perineum?
Corresponds to the bony pelvic outlet
What is the shape of the perineum?
Diamond shaped area
Where is the perineum located?
- Inferior to pelvic floor
- Between upper thighs
What does the perineum contain?
Openings for urogenital and GI systems
What is the anterior boundary of the perineum?
Inferior pubic symphysis
What is the posterior boundary of the perineum?
Tip of coccyx
What is the lateral boundary of the perineum?
- Ischial tuberosity
- Ischiopubic rami
- Sacrotuberous ligaments
What is the roof of the perineum?
Pelvic floor (levator ani)
What are the two triangles the perineum is divided into?
- Urogenital triangle
- Anal triangle
Where is the urogenital triangle located?
- Anteriorly
- Faces more inferiorly (horizontal plane)
What does the urogenital triangle contain?
- AFAB and AMAB external genitalia
- Urethra
- Associated neurovasculature
Where is the anal triangle located?
- Posteriorly
- Faces posteriorly
What does the anal triangle contain?
- Anal canal and sphincters
- Anus
- Ischiorectal fossae
- Associated neurovascular structures
What is the defining feature of the urogenital triangle?
Perineal membrane
What is the perineal membrane?
Tough, triangular, fibrous sheet between ischiopubic rami, pubic symphysis, and ischial tuberosities
What edge of the perineal membrane is free?
- Posterior edge
- Except at the perineal body
What is the perineal membrane an attachment surface for?
- Erectile tissues
- Muscles of external genitalia
What does the perineal membrane contain?
- Urethral openings (AMAB and AFAB)
- Vaginal opening (AFAB)
What does the perineal membrane separate the urogenital triangle into?
- Superficial perineal pouch (SPP)
- Deep perineal pouch (DPP)
What is contained in the SPP?
- Erectile tissues
- Muscles
- Superficial transverse perineal muscle
What is contained in the DPP?
- External urethral sphincter muscle
- Deep transverse perineal muscle
- Bulborethral glands (AMAB)
What is the perineal body?
- Central tendinous structure of the perineum (fibrous skeleton)
- Where muscles of the pelvic floor and perineum attach
Where is the perineal body located?
At the boundary of urogenital and anal triangles
Which triangle is more variable between the sexes?
Urogenital triangle
What structures does the anal canal contain?
Same for both AFAB and AMAB:
1. Anal canal
2. Internal/external anal sphincter
3. Anus
4. Associated neurovascular structures
What is the anterior boundary of the anal triangle?
Imaginary line between ischial tuberosities
What is the posterior boundary of the anal triangle?
Tip of the coccyx
What is the lateral boundary of the anal canal?
- Ischial tuberosity
- Sacrotuberous ligament
What is the roof of the anal canal?
Levator ani
What is the ischiorectal fossae?
- Levator ani, distal rectum, anal canal, and external anal sphincter make a cone shape
- Creates two spaces on either side of it
What are the ischiorectal fossa filled with?
Plenty of adipose tissue
What are the ischiorectal fossae continuous with anteriorly?
Deep perineal pouches
