Perineum Flashcards
In strict anatomical terms, where is the perineum and what does it contain?
It is the narrow region between the proximal parts of the thighs inferior to the pelvic diaphragm
It is functionally defined as the outlet of the pelvis and contains:
Anal canal, anal aperture, and associated sphincter muscles
Distal urethra, external openings of the urinary tract, and associated sphincter muscles
Lower vaginal canal and external orifice (in females)
External genitalia and fascial layers/muscles that support them
What are the three bones of the ox coxa and at what age do they fuse?
- Ilium superiorly
- Ischium posteroinferiorly
- Pubis anteroinferiorly
Fuse at 18 years of age
Which ox coxae bones fuse first and what is their connection called?
Pubis and Ischium creating the ischiopubic ramus
What connects the ox coxae posteriorly and anteriorly?
Posteriorly - sacrum by the sacroiliac joints and reinforced by:
(Superficial to deep)
1. Anterior sacroiliac ligaments
2. Interosseous sacroiliac ligaments (strongest)
3. Posterior sacroiliac ligaments
Anteriorly - symphysis pubis and reinforced by:
- Superior pubic ligament
- Inferior pubic ligament
What is an important landmark at the S1 vertebra?
Sacral promontory
What are the parts of the linea terminals?
- Arcuate line of the ilium
- Pecten pubis (AKA pectineal line) of the pubis
- Pubic crest of the pubis
What and where do the sacrospinous ligament and sacrotuberous ligament connect?
Sacrospinous ligament (more anterior) - connects sacrum to the ischial spine
Sacrotuberous ligament (more posterior) - connects sacrum to the ischial tuberosity
How do you form the urogenital triangle and the anal triangle?
Urogenital triangle - draw a line between the ischial tuberosity and then two lines towards the symphysis pubis
Anal triangle - draw a line between the ischial tuberosity and then two lines towards the coccys
What nerve fibers controls the external anal sphincter?
GSE nerve fibers from the inferior rectal nerve (S2-S4) which branched off from the pudendal nerve
What nerve fibers controls the internal anal sphincter and what do they do?
GVE (parasympathetic and sympathetic)
Parasympathetic - opens sphincter
Sympathetic - closes sphincter
What courses through the pudendal canal?
Pudendal nerve
Internal pudendal artery/vein
What forms the pudendal nerve?
It is a branch from sacral plexus formed by S2, S3, S4 anterior rami
What are the branches of the pudendal nerve?
- Inferior rectal nerve (first branch)
- Perineal nerve
- Dorsal nerve of penis or clitoris
What and where do the nerve fibers of the inferior rectal nerve provide?
GSE to external anal sphincter and GSA to the anal canal below the pectinate line
The inferior fascia of the UG diaphragm is also known as what?
Perineal membrane