hello anatomy colleagues this is dr alsup and while we have had many many discussions already
regarding the urinary system this video we will be discussing the more distal portions of this
system so the urinary system as associated with the pelvis and so there are three main areas we
will be discussing the pelvic portion of the ureters the urinary bladder and the urethra
so let's start with the ureters as i hope these structures are already quite familiar to you
as we did discuss them in some detail during the renal section and as you know the ureters are two
muscular tubes that will allow the transport of urine from the kidneys as it is continuous with
the renal pelvis to the urinary bladder and they are approximately 25 to 30 centimeters in length
and there are three major parts we have already explored this first part which is the abdominal
part it descends anterior to the psoas major muscle and this will transition to the pelvic part
after it crosses over that bifurcation of the common iliac arteries to enter the pelvic cavity
the pelvic part as its name would suggest is in the pelvic cavity and as this is a really
relatively complex and crowded area it has close geographical relationships with many structures
but of most clinical importance it is very closely related to the to the uterine artery on its course
to the bladder so you can see that here near the uterine cervix it also has a close relationship to
the ductus deferens and the seminal vesicles which would be located near the base of the bladder
the last portion of the ureter is actu is where it actually runs
within the wall of the urinary bladder at its base and this is referred to as the intramural part
and this is actually the narrowest the narrowest part of the ureter
all right so now let's move to the urinary bladder which is located in the anterior portion of
the pelvic cavity its size and its shape will vary dependent on the amount of urine present
as well as the state of any neighboring viscera so there's a lot of movement and a lot of change
that can occur in the bladder when the bladder is empty it lies completely within the lesser pelvis
but it can extend into the abdominal cavity as it expands there are numerous surfaces
and parts of the bladder but we're going to focus on these three starting with the apex
the apex of the bladder always faces towards the pubic symphysis and it will be superior posterior
to the to the pubic symphysis so you can kind of see it kind of right here here is the pubic
synthesis recall that's that cartilaginous joint on the anterior portion of the pelvic girdle
recall that the median not the medial the median umbilical fold which is formed by
peritoneum covering the medial umbilical ligament and that uh the media median umbilical ligament
is a remnant of the uracus which connects the apex of the bladder to the umbilicus
all right the base or sometimes you hear it referred to as the fundus of the bladder is
its posterior most wall and it is here that those intramural parts of the ureters will
enter into the bladder so that's going to be more towards this portion here
lastly the neck of the bladder
is inferiorly placed and it is almost completely fixed meaning that there should be very little
movement or change in shape of this portion of the bladder unless there is a change in
the muscle or the ligaments around this area which can affect urinary continence
it is very closely geographically related to the vagina or the prostate now speaking of
the internal bladder there is a grossly visible trigon which is outlined by the two slit-like
ureteric orifices
and the internal urethral meatus which is in this general region here and you can see
that this forms a trigon or a triangular shape an individual's past middle age with a prostate
there may be an elevation immediately kind of behind the internal urethral meatus of this
general region right here and this is caused by what is often termed the median prostatic lobe if
this area increases in size this can affect the flow of urine in this area lastly let's discuss
the urethra which is a sexually uh sexually polymorphic area we will be discussing two of
the most common organizations of the urethrae with the first being the organization of the urethra
and individuals assigned female at birth in adults this urethra is typically about four centimeters
long so i'm going to kind of outline this area here it will extend from the internal urethral
meatus to the external urethral meatus that makes sense those names make sense with the in-between
length traveling anterior anterior inferiorly and kind of intermediate to the pubic symphysis
and the vagina so it'll be an intermediate and placement there and as mentioned it will
terminate in the external urethral meatus which is located in the vestibule of the vagina which is
often just referred to as the vestibule and in the vestibule the external urethral meatus is located
around 2.5 centimeters posterior to the glans clitoris and anterior to the opening of the vagina
all right so you can see that right here here's the opening of the vagina or the vaginal opening
the urethra of individuals typically assigned male at birth
is comparatively longer at about 18 to 20 centimeters long but again extending from the
internal urethral meatus to the external urethral meatus there are three major parts of the urethra
for these individuals with a fourth part sometimes mentioned the pre-prostatic part which is the very
short portion that extends from the base of the bladder to the prostate the prostatic part
will extend through the prostate as its name would suggest so you can see that right here
and it is the it is at the prosthetic urethra that the contents of the ejaculatory ducts and the
prostatic ducts will enter the urethral system the membranous part or membranous portion of
the urethra will traverse the pelvic diaphragm which is right here so it's a short area right
in that region and this will lead into the spongy or penile portion of the urethra and
this is going to start at the bulb of the penis and it'll look which which
we know the the bulb is composed of corpus spongiosum erectile tissue and it will extend
through the corpus spongiosum of the of the body of the penis to the distal portion
of the glans penis where the urethra ends at the external urethral meatus
so you can kind of follow this here in an illustration as well
through the length of that corpus spongiosum all right excellent job we have made it to the
summary slide please take your time to review and relate the information that we have learned
during the renal portion of your curriculum as always please please feel free to reach out to
me or any of my anatomy colleagues with any questions and have a great rest of your day