DR1: Pelvic Floor Flashcards
What is the perineal membrane?
Thick fibrous membrane sitting beneath the pelvic diaphragm
What is the pelvic diaphragm?
Formed by the muscles of the pelvic floor
What is the pubic arch?
Runs between the lower edge of the pubic body and the two ischial tuberosities
What is the deep perineal pouch?
Formed by the anterior and posterior free edges of the perineal membrane folding upwards
What perineal muscles are in the deep perineal pouch?
Compressor urethrae, utherovaginal sphincter in females
Describe the superficial perineal pouch.
Inferior to the perineal membrane containing skeletal muscles responsible for erection
Describe the perineal body.
Found midway along a line joining the two ischial tuberosities
Site where fibres from several muscles of the superficial perineal pouch converge.
What muscles cover part of the pelvis wall?
Piriformis
Obturator internus
What is the passageway for the somatic sacral nerves?
Anterior surface of the sacrum
Describe the piriformis muscles.
Lies on anterior surface of the sacrum
Describe the obturator internus muscle location.
Passes beneath the obturator foramen
Describe the tendinous arch.
Used to locate the obturator internus muscle
Describe the muscles of the pelvic floor.
Levator ani
Coccygeus
What features are associated with the pelvic floor?
Internal surface of the body of pubis
Ischial spine
Coccyx
Tendinous arch
Origin and insertion of iliococcygeus
Tendious arch projects from ischial spine to posterior aspect of pubic bone to coccyx
Origin and insertion of Pubococcygeus
From internal surface of the pubis to the coccyx
Origin and insertion of puborectalis
From pubis with fibres inserted behind the rectum
Origin and insertion of coccygeus
Inner surface of the ischial spine to lateral margin of the coccyx and side of the 5th sacral segment
Roots of the sacral plexus
Formed by anterior primary rami of S1-4
Course of the obturator nerve
Exits the pelvis via the obturator foramen
What nerve remains in the pelvis?
Piriformis nerve
Lumbosacral trunk
Sacral plexus is joined by the anterior primary rami of the lumbar L4,5
Sciatic nerve
L4,5, S1-3
Largest nerve in the body and largest branch of the plexus
Superior gluteal nerve
L4,5 plus S1
Inferior gluteal nerve
L5, S1, S2
Pudendal nerve
S2-4
Exits the pelvis through the greater sciatic foramen then re-enters through the lesser sciatic foramen by crossing over the ischial spine
Main branches of the lumbosacral trunk
Sciatic nerve
Superior gluteal nerve
Inferior gluteal nerve
Pudendal nerve
Important structures of the posterior pelvis
Sciatic nerve
Pudendal nerve
Gluteal vessels
Sciatic nerve
Widest nerve in the human body as a large amount of myelin is required to insulate the long axons
Found inferior to the piriformis muscle (rarely the nerve passes through the piriformis muscle to cause sciatica)
Clinical significance of the sciatic nerve
In order to avoid the nerve, injections into the buttocks are always done both lateral and high
Pudendal nerve
Target of pudendal block for anaesthetic drug to numb perineal region
When is a caudal epidural more common practice than a pudendal nerve block?
When used to alleviate labour pain
Superior gluteal artery
Exits the pelvis through the greater sciatic foramen and superior to the piriformis muscle
Inferior gluteal artery
Exits the pelvis through the greater sciatic foramen and inferior to the piriformis muscle
Superior and inferior gluteal veins
Adjacent to superior and inferior gluteal arteries
