hello everyone this is dr fox and let's talk about the perineum before we do however i'd
like to just generally address the fact that sex is not binary medically and biologically speaking
of humans there are at least five different recognizable types of sex possibly even more
when thinking about sex i often reflect on the quote from hamlet when hamlet said directly that
there are more things in heaven and earth ratio than are dreamt of in your philosophy but come sex
and gender are complex topics and the language that we use when addressing them or related ideas
is important in anatomy traditionally we discuss structures that are sexually dimorphic meaning
different in males versus females and we know that this language is wholly insufficient
in describing anatomy differences among genders and so i prefer to think of terms that are more
sexually polymorphic meaning not just limited to males and females however this being a
foundational anatomy course sometimes we find ourselves sort of stuck with the trope of sex as
a binary at times when we're closer to to this notion than not we may use terms like assigned
female at birth or assigned male at birth and this isn't a recognition of the binary nature of
sex as as a topic but rather a heuristic at describing two of the more typical types of
sexual polymorphisms and so i would invite all of you to to think broadly
and inclusively as we move through this and you know i hope that i myself may evolve to be
more broad and inclusive with respect to my own thoughts and my own language so thank you
in this particular video we're going to discuss the boundaries of the perineum and understand the
location and function of the perineal body so the perineum is a diamond shape region
that is going to sit superficial to the pelvic floor so those muscles of the pelvic diaphragm
it's best construed as two non-coplanar triangles so anteriorly we will have a urogenital triangle
that urogenital triangle is going to have anterior lateral borders of ischiopubic array mine
and will be divided from the anal triangle by the inter-ischial line
the inter-ischial line is an imaginary line that's going to run between the ischial tuberosities or
the portions of your ischial bones or your sit bones upon which contact is made when
seated the posterolateral boundaries or borders of the perineum are the sacrotuberous ligaments
and these are roughly correlated to where the anterior inferior borders of the gluteus
maximus muscles are so as you can see these aren't perfect triangles but they are roughly approximate
now let me erase this for a second if we look at the midline here and we see
in the general area where that midline intersects with the interischial line
we are in the vicinity of the perineal body so that perineal body is a musculofibrotic
condensation of tissues where the muscles of the urogenital triangle so the
bulbospongiosus muscles here as well as the transverse perineal muscles
superficial as well as deep come together with the external
anal sphincter and so all of these muscles are going to interdigitate as will their
fasciae and that is going to form the perineal body it's not a constant
structure but it is a fairly typical palpatable structure through the skin and it's going to be
of importance in maintaining the integrity and actions of these muscles and vaginal delivery
either through injury or through purposeful incision such as an episiotomy may endanger
this structure and that can lead to anal or rectal tearing now let's turn our attention to
that eurogenial triangle again with its boundaries as the ischiopubic rami which are coming
together anteriorly at the pubic symphysis and its posterior boundary being that inter-issue
line we can see that it contains the urogenital hiatus that is the space through which the urethra
may be conducted it's also the space through which the vagina may be conducted
the urogenital triangle is a complex arrangement of layers and structures three-dimensionally it is
very very complex it's going to run from the skin down to levator ani and it's going to include
various features of the vulva such as the labia majora and minora the vestibule of the vagina
the clitoris the erectile tissues and the muscles associated with them the perineal membrane etc
this will be a topic of a subsequent learning objective and video it also can include the
root of the penis so that's where the the crura of the penis are going to converge with the bulb of
the penis and also be inclusive of the the scrotum the fleshy sac in which the testes are maintained
posterior to the very complex urinal triangle is the more simple anal triangle
so the posterior lateral borders here are those sacrotuberous ligaments the anterior boundary is
going to be the interischial line and its most prominent feature is going to be the
external anal sphincter and the anal canal which the sphincter surrounds and flanking the uh
the external anal sphincter and the anal canals are going to be the ischiorectal fossa
which i'm kind of outlining here
those ischiorectal sometimes called ischioanal fossae are the uh
are the empty spaces um that aren't quite empty they're filled with adipose connective tissue
through which the pudendal nerve which supplies the perineum
with innervation as well as the internal pudendal artery which supplies the perineum
with blood as well as the internal pudendal vein which drains the perineum of blood
and their branches and tributaries are all conducted and we'll see this in greater detail
in a subsequent learning objective and video so we've discussed the idea of sex as a continuum
as well as the perineum and the urine genital and anal triangles and some of their contents
as well as the perineal body this is your summary slide i thank you for your time