hi let's talk about the pelvic diaphragm and the perineum the pelvic diaphragm is a series
of muscles which supports the pelvic viscera and resists intra-abdominal pelvic pressure so the
two major components of the pelvic diaphragm are the levator ani muscle and the issue
coccygeus muscle sometimes just referred to as the coccygeus muscle now the levator on the muscle
is going to extend from anterior and lateral aspects of the bony pelvis to posterior and
lateral aspects of the bony pelvis so much of this we cannot see because it's obscured by features
of the urogenital triangle so namely the perennial membrane and ischio cavernosus mobile cavernosus
muscles as well as transverse perennial muscles which we can see all throughout here
but we can see some of these muscles let me just outline the external anal sphincter for us
here so let's start with the more medial fibers of levator ani these include the puborectalis muscles
so the puborectalis muscles are going to form a sling around
the anorectal junction so if you recall the rectum is a little more anteriorly facing and
the anal canal is more posteriorly facing owing to this sling that's that's placed on it so these
fibers are originating from the posterior aspect of the pubis and then meeting their counterparts
around the anorectal junction there are also the coccygeus muscles the pubococcygeus muscles
are running from the posterior portions of the the pubic bones as well as the uh the ischiopubic rami
there's somewhat of a condensation of connective tissue called the tendonous arc of levator ani
that those muscles are going to originate from and they're coming back to insert on the coccyx
and some of the the connective tissues of the anococcygeal raphae
which is going to run between the anal canal and the coccyx the third and final part
to the levator ani muscle are the iliococcygeus muscles
the iliococcygeal muscles are um originating from that tendonous arc of levator ani and coming
together to uh to insert on the uh the coccyx and that anococcygeal raphae and you can see
they're fibers running this way
and then finally to to round out the the pelvic diaphragm we have the issue coccygeus muscles
the ischiococcygeal muscles
are more wedge shape and they run from the ischial spines and
there's actually connective tissue there that is part of that tendinous arc of levator ani
and they're coming together along the midline on a little bit of the sacrum
largely on the coccyx which we can see here and a little on that anococcygeal raphe
so here we have the levator ani and ischiococcygeus muscle when we think of the perineum
we need to think of all of these structures which are superficial to that pelvic diaphragm
let's review the boundaries of the perineum so anterior laterally we have the ischiopubic
rami posterior laterally we have the sacrotuberous ligaments and we can see that the coccyx is
invading that space as well and separating two triangles here we have an inter issue line
which anteriorly separates the urogenital triangle from posteriorly the anal triangle
that urogenital triangle is going to host the urogenital hiatus which is this space here
that your genital hiatus is the space through which the urethra and the vagina
are conveyed surrounding that space we see some bulbospongiosus muscle
now the anal triangle is going to host the external anal sphincter which we can see there
and it's where fibers of that external anal sphincter and bulbospungiosus muscle as well as
the transverse perennial muscles are going to come together in that musculotendinous intersection
which is known as the perennial body that perennial body is a site of central support
that is common between the year genital and anal triangles so over here
we can see we can see some donors with the skin intact and i can just roughly draw for you the
the boundaries of the perennial here so that we can have an appreciation for
the superficial tissues and how they relate to the perennia
like so you can also see that uh that structures that are part of the vulva
or external female genitalia are part of the perineum as
are structures of the the penis inclusive of
the scrotum so we've discussed the pelvic diaphragm and the perineal
thank you very much for your time