Description: The levator ani are bilateral m. composed
of the right and left pubococcygeus m. anteriorly, and the iliococcygeus,
in the midpelvis. Posteriorly, the levator ani muscles join the coccygeus
m. to complete the pelvic floor, a trough-shape space sloping anteroinferiorly.
The pubococcygei are separated anteriorly for the urethra and vagina to
penetrate, and the anus emerges through the coccygei m. They originate
on each side from the tendinous arch, suspended atop the obturator internus m., originating
from the inner surface of the pubis anteriorly, and from the ischial spine, posteriorly. The levator ani m. are attached to
the anococcygeal raphe in the midline and coccyx,
forming the 'hammock-like' pelvic diaphragm. A
thin, horseshoe-shaped muscle, the puborectalis, circling posteriorly
about the anorectal junction
and attaching to the pubis anteriorly, is also part of the pelvic diaphragm.
The levators derive circulation
from the parietal branches of the internal iliac a., and innervation
from S4, via the pudendal n.. |