Part 11: Pelvic Cavity Flashcards
What bones form the pelvic brim?
pubic crest, pectineal line, arcuate ligament of ilium and ala and promontory of the sacrum
What angle doe the pelvic brim lie?
60’ with the horizontal plane
What are the differences between male and female pelvis?
Female: broader, wide subpubic angle, less sacral indentation
Male: Narrow, acute subpubic angle and heart shape sacral promontory projecting forwards
What is the important horizontal plane in the pelvis?
From upper border symphysis pubis to tip of the coccyx.
Passes through spine of ischium spine, head of femur and apex of GT. At level with tip of finger in rectal or vaginal exam. Also seminal vesicles and ovaries lie in this plane.
What is the origin, insertion, action and innervation of piriformis muscle?
O: S2,3,4 costotransverse bars of anterior sacrum between sacral foramina
I: Ant part medial aspect GT
A: Lat rotates and stabilises hip
N: Anterior rami S1+2
What is the origin, insertion, action and innervation of obturator internus muscle?
O: Inner surface obturator membrane, rim of pubis and ischium bordering it
I: Middle part of med aspect GT
A: Lat rotates and stabilises hip
N: Nerve of obturator internus (L5, S1,2)
Muscles of the pelvic floor are?
coccygeus and levator ani
Coccygeus is often called ischiococcygeus
Levator ani consists of iliococcygeus and pubococcygeus
What is the origin, insertion, action and innervation of coccygeus muscle?
O: Sacrospinous ligament and ischial spine
I: Lowest part sacrum and coccyx
A: Supports pelvic viscera
N: Perineal branches of S4+S5
What is the origin, insertion, action and innervation of iliococcygeus muscle?
O: Posterior half of white line (arcus tendineus) and ischial spine
I: Anococcygeal ligament and coccyx
A: Supports pelvic viscera
N: Perineal branches (S3+4)
What is the origin, insertion, action and innervation of pubococcygeus muscle?
O: Anterior half of white line (arcus tendineus) and posterior pubis
I: Coccyx and anococcygeal ligament
A: Supports pelvic viscera
N: Perineal branches (S3,4)
What is the U shaped ring that holds the anorectal junction forward called?
puborectalis
What is the U shaped ring that passes behind prostate in male and behind vagina in females called?
Levator prostatae in males
Pubovaginalis in females
What lies in the gap anteriorly, medial to the puboprostatae/pubovaginalis?
Puboprostatic ligaments in males
Pubovesical ligaments in females
More medial still lies deep dorsal vein to clitoris/penis
What is the nerve supply of the pelvic floor?
All levator ani supplied by branches of perineal nerve (S3,4)
The external sphincter (seperate to levator ani) is supplied by inferior rectal branch of pudendal nerve (S2)
How does the pelvic fascia vary?
Fascia of pelvic wall is very strong covering muscles firmly attached to periosteum (Fascia of Waldeyer)
Fascia of floor is much thinner - more of epimysium, allowing more movement.
