hi let's talk about the urogenital triangle in this video we'll discuss the structures of the
urogenital triangle with a particular emphasis on the structures of the superficial perineal space
or superficial perineal pouch so the urogenital triangle to review is
the portion of the perineum which is bounded by the ischiopubic rami and separated from the
anal triangle by the interischial line now this region of the perineum is going to be
very complicated and contain a number of layers and structures within those layers much like
most of the rest of the body the most superficial layer is the skin and deep to the skin we'll have
the superficial fascia or the subcutaneous layer and deep to the sub-q will be the
superficial perineal space this space is going to include erectile tissues as well as muscles which
surround those erectile tissues those erectile tissues include the corpus cavernosum and corpus
spongiosum the cavernosum is going to be more lateral the spongiosum is going to be more medial
and i just want to point out for a second that illustrations are labeled you know female or male
but we know that sex is not a binary that these structures are going to exist upon a continuum
and so our language should be more inclusive than that it should be more sexually polymorphic and
these are just labels of expediency now upon these erectile tissues we can see specialized muscles
so laterally on elements of the corpus cavernosum we have issue cavernosus muscles
and on muscles of the corpus spongiosus or on corpus spongiosum we have the bulbospongiosus muscles
and we'll discuss those in a little greater detail shortly but these are all within that superficial
perineal space the superficial perineal space is divided from the deep perineal space by the
perineal membrane which we can see here and that deep perineal space is a very irregularly
shaped space between the perineal membrane and the muscles of the pelvic floor or the
levator ani muscles so here is a more detailed version of this what we're looking at on the right
hand side is a coronal slice through the perineum as well as some of the um the subperitoneal
space inclusive of the urinary bladder so we can see here's the urinary bladder inferiorly
and here is the urethra so facing superior in this case so let's take a look at some of these layers
so here is the skin and deep to the skin is the sub-q and that sub-q is going to have a fatty
layer to it sometimes called Camper's fascia same as the camper's fascia lining the abdomen
and through that camper's fascia in this particular illustration we can see the
round ligament of the uterus running through and inserting into the labium majus here
and then the deep layer of that subcutaneous layer is the Colle's fascia or the deep membranous
layer there the superficial perineal space is going to be deep to the the deep membranous
fascia and it's going to be superficial to this perineal membrane here so we're talking about
this space here what's included in this space will be the erectile tissues and here we can see the
vestibular bulb or we can see the vestibular bulbs here that would be flanking the the vestibule of
the vagina and surrounding the vestibular bulbs will be the bulbospongiosis muscles
the derivatives of the corpus cavernosum so in this case they would be the the crura of the uh
the clitoris would be more lateral and they're not included in this particular illustration
it's also um in this particular level
that the muscles so bulbospongiosus and transverse perineal muscles are going to
deviate towards the the midline and participate in the perineal uh body
there are also at least in assigned female at birth individuals
going to be greater vestibular glands or Bartholin's glands these are glands that we
cannot see in this particular level but are going to be associated with the inferior most extent
of the vestibular bulbs and these are going to secrete into the vestibule of the vagina
and serve as a lubrication for that region then there's the perineal membrane and deep to that
perineal membrane we have the deep perennial space that deep perennial space is going to be
bounded by the pelvic diaphragm so it is going to be quite unique in its shape and includes
some of the compressor urethra muscles as well as in assigned male at birth individuals the
bulbo urethral glands or the calipers glands urethral glands and greater vestibular glands
are homologous with one another so an individual will either have greater vestibular or bulbourethral glands and they serve the the same function to provide some form of lubrication
so let's take a a look at these erectile tissues and associated muscles keeping in mind that they
are going to be sexually polymorphous there are two types of erectile tissues
there is the corpus cavernosum and the corpus spongiosum the corpus cavernosum
is paired generally and so we refer to the two portions of it as the corpora cavernosa
muscles and these are going to be more laterally distributed so these are going to form crura
or legs and the crura are associated with the ischiopubic rami so there's a crus there is
another crus so here we have the crura of the clitoris and here we have the crura of the penis
medially these krura are going to unite um and and they unite along the midline as we'll see um
and the crura are going to be covered by ischiocavernosus muscle so here we can see the ischiocavernosa muscle there in association with the issue of pubic rami or ramus and there are the
issue cavernosus muscles there the corpus spongiosum is more of a midline structure
it may be divided or it may be one uh midline unit so in in the case of the vestibular bulbs
we can see that the corpus spongiosum happens to be divided here and flank either side of the
vestibule of the vagina it does come together to form the shaft or body of clitoris there oh i'm
i'm so sorry i i misspoke it it does come together to form uh the glans clitoris
the glans is the most visible
portion of the clitoris and colloquially is what many people mistakenly refer to as
the clitoris but we can see that the clitoris is a much more robust and varied structure here
we can see over here the corpus spongiosum forms the bulb of the penis and that extends
into the body or shaft of the penis and distally it will form the glands of the penis but that's
that's not illustrated here we could also take a moment to uh to note the greater vestibular glands
those greater vestibular glands are found in association with the inferior portions
of the vestibular bulbs and again they're going to drain into the vestibule of the vagina like so
we can also see the bulbospongiosum muscle bulbospongiosus muscles depending
those bulbospongiosus muscles are going to cover the derivatives of the corpus spongiosum
and either the the issue cavernosus muscles or the bulbospongiosus muscles are going to apply
pressure to those erectile muscles uh to aid in tumescence
now here we can specifically look at the erectile muscles that are participating
in the clitoris so we've got the crura of the clitoris here
that are formed of the corpora cavernosa they come together along the midline
and they fuse to form the body or the shaft of the clitoris
and then we have the corpus spongiosum forming vestibular bulbs
and then those vestibular bulbs are going to come together along the midline
to cap off the body of clitoris as the glans clitoris so corporate cavernosa are the
crura and body or shaft of clitoris whereas corpus spongiosum are the vestibular bulbs
and the glans clitoris um both of these are going to be served by specialized branches of
the internal pudendal artery which is a branch of the internal iliac artery
and they're going to be serviced as well as the remainder of the perineum by branches of the
pudendal nerve now all of this pudendal vendal that comes from the latin podera which means
to be ashamed um i can speak as an anatomist first and as a person second these
notions of any particular portion of the body being shameful uh really has no
scientific merit to it so uh chin up and uh don't uh don't be ashamed of of this particular
region of of your anatomy now let's look at the erectile tissues in the assigned male at birth so
the corpora cavernosa are going to form the crura of the penis those crura of the penis are going to
come together and unite as a portion of the shaft of the of the penis there's also um
a bulb of the penis so that is corpus spongiosum um and that bulb is going to unite with the crura
of the penis and the three elements here of the penis and bulb of the penis is known as the root
of the penis
and that is a portion of the superficial perineal pouch beyond the corpus spongiosum
will be a part of the body or the shaft of the penis
and laterally here this is a good view we can see there's the bulb
of the penis and we can see the corpus spongiosum taking an inferior position
within or a ventral position within the shaft of the penis and then at the
distal portion of the penis there's a large dilation of this tissue to form the glans penis
so if we're looking at the the cross section of the body of the penis we can see there are
corpora cavernosa here which are superiorly or dorsally
unified together and then we can see eventually we've got the corpus spongiosum
and that is surrounding the spongy portion of the urethra so recall the urethra is tripartite there
is the prostatic part of the urethra and then the membranous part of the urethra and then the
spongy part of the urethra gets that name spongy because it goes through the corpus spongiosum
the the penis and its erectile tissues are served by branches of the internal
pudendal artery we can see some of them here so these are the deep arteries
of the penis we can also see some of the dorsal arteries of the penis there
and the penis is like the rest of the perineum served by branches of the pudendal nerve and
again nothing to be ashamed of here so poor nomenclature on on the part of ancient anatomists
so we've discussed the uh the complexity of the eurogenial triangle with a particular emphasis
on the superficial pouch in there the erectile tissues found within the superficial pouch
and their derivatives the muscles associated with those erectile tissues and the blood
supply and innervation of those tissues this is your summary slide i thank you for your time