Where is the urethra in a male
Urethra (anatomy)
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you might be able to hear the steady
thrum of the air conditioning units
keeping the computers cool in another
building nearby not keeping the people
cool keep the computers cool it's not
too bad in here actually but we're
having a bit of a heatwave in Britain in
the moment as we seem to be having every
year there might be a bit of a trend
there right you can also hear the
seagulls occasionally bear drilling I'm
not grumpy cousin yeah I'm grump because
it's hot right onto the topic we've
looked at the kidneys we've looked at
the ureters we've looked at the bladder
we look to the bits of the mainland
female reproductive systems now we're
gonna look at the last bit we're gonna
look at the urethra of course we're
gonna have to look at two urethra me I'm
gonna have to look at the male urethra
which was longer more complicated and
maybe more interesting and we're going
to have to look at the female urethra
because they're a bit different about
the functions a little bit but the main
focus here is on the anatomy so on the
part the features where they run an ass
or thing and we'll talk very briefly
about blood supply in innovation because
it is brief functions well there's a
very obvious one right in both male and
female pelvis is the function is to
carry urine from the bladder to the
outside environment so it carries and
she part of it there it carries a urine
externally we can see part of the male
urethra here part the male urethra here
so Mayo urethra is obviously a lot
longer because there's a penis so the
bladder collects the urine stores a year
in and then when you're a child you
learn to store that urine until a
convenient time to get rid of it and the
sphincters open and the urine passes
from the bladder through the urethra to
outside in the male pelvis the urethra
is also the route the spermatozoa will
take to pass from the testes route and
components of semen will be put into the
urethra so all that stuff gets put into
the urethra event
actually and then follows the urethra
right through the tip of the penis
through the external urethral orifice so
those are the functions of the urethra
tell you what if we're talking about the
functions of the male urethra let's talk
about the parts of the male urethra
first then we'll do the female because
it'd be really short for that has an
Anatomy joke there are four pass to the
male urethra it's around 20 centimeters
long you might imagine that it is a
little bit variable in length and can
even change lengths somewhat and the
first part if we start at the bladder is
the pre prostatic part which is a very
sensible name so it's the bit of the
urethra before the prostate but you can
see the prostate gland is pushed up Y up
against the bladder so that's kind of a
difficult thing to visualize but it's
it's kind of that B there there is a
you've got the detrusor muscle of the
bladder so the muscle around where the
urethra leaves the bladder gets called
the internal urethral sphincter in the
male bladder there's a proper swing to
there that can block this off purpose of
that during ejaculation it makes the
semen and the spermatozoa go in the
right direction not up into the bladder
but the prostatic part of the aretha
which also gets called the intramural
Park is that first part there so as the
bladder fills and stretches an
thing it can change in size and length
and shape a little bit a little bit
stretchy but that's it so the the next
part the second part is the part of the
urethra that's running through the
prostate gland and that's the prostatic
pathway we throw all good so far however
if we look at the urethra within the
prostate gland it's got a few strange
parts to it so if we if we look at this
from a slightly different perspective
right this is a coronal section here's
the prostatic part of the urethra there
and this isn't I mean I don't think I've
got any models of the show this
beautifully but there is a little bit of
a widening there there's a bit of an amp
puller and what we're seeing here we're
seeing some embryological remnants
really there's there are prostatic
sinuses in these spaces I
the side we see seeing on the posterior
wall of the prostatic urethra here is
this there's kind of a ridge sticking
out for me and that's the urethral crest
and that urethral crest kind of looks
like it fattens there and becomes a
seminal colliculus and there's a little
bit of space in there which is called
the prostatic utricle none of this
information is is really important to
know about but if you're wondering what
those names mean and what these little
lumpy bumpy structures are that's what
they are and what happens here so when
the male and female embryos start to
form the structures in this region they
start off using essentially the same
tubes and then they start to form
different structures or some tubes
disappear and some tubes hang around
anyway this is a remnant of that and
that prostatic utricle isn't anything
there's kind of like a little blind
ending sac in there which if it was to
develop in the female embryo mind go on
and form other sac like things nearby
only that's your imagination but right
next to that little opening there into
the prostatic utricle which is included
on this model on either side of that are
the two ejaculatory ducts and the two
ejaculatory ducts are where the two
ductus deferens tubes essentially duct
into the urethra so they're docked into
the urethra at the level of the prostate
gland and then if you were to look even
more closely you'd see lots and lots and
lots and lots of lots of tiny little
ducts from the prostate gland itself
opening into the urethra here so this is
where everything mixes as it were so you
have the spermatozoa passing in here
through the ejaculatory ducts you have
the secretions from the seminal vesicles
which are nearby secreting into the
ejaculatory duct into this space and the
prostate gland is also then secreting
into this space here during ejaculation
if we go back to this model the
ejaculatory ducts are coming in from
either sides if you just look in the mid
sagittal section you don't see them but
if you if you cut a little bit off to
the side you can see the ejaculatory
ducts here so there's a seminal vesicle
and
left the ductus deferens there coming
together there and there would be two of
these ejaculatory ducts ducting into the
urethra at this point in the prostatic
urethra so if you're looking at the
prostatic part of the male urethra in
the posterior war you'll see a ridge
sticking out and that's the urethral
crest now urethral crest where it widens
gets called the seminal colliculus and
inside there there's this kind of
useless blind ended sack with a little
opening here and that's the prostatic
utricle and then the spaces around that
the widening of the urethra there those
are the prostatic sinuses and then we
move on to the third part which is is
how we're going to see the third part oh
so here's the male urethra in its full
length
so I mean easiest way to but the third
part is is this bit here this is the
membranous part of the urethra
essentially the easiest way to remember
this is the fourth part is the spongy
urethra and if you know the anatomy of
the penis you'll know that this is the
corpus spongiosum this is one of the
ejaculatory or one of the erectile
bodies so the spongy part of the urethra
is running through the corpus spongiosum
hence its name so the bit of the urethra
between the prostate and the spongy part
of the urethra is the membranous urethra
and this is the bit that is passing
through the pelvic floor right it's
passing through
through that this musculature the
supporting the pelvic floor is here that
we find the external urethral sphincter
which is a bit of muscle under somatic
control that's the bit you can hold when
you really need to hold it so it's
passing through there passing through
the perineum membrane and this level
we're seeing bolbo urethral glands but
in fact the Bobble urethral glands they
ducked into this first part of the
spongy part of the male urethra so the
spongy part of the urethra starts at the
perineal membrane and runs within the
corpus spongiosum all the way out to the
glans
and the external urethral orifice here
which is where it opens and there are
two windings to ampulla the little
widening of the star is the intra bulbar
fossa and the widening in the glans
penis is the navicular fossa navicular
boat and as well as the bulb or urethral
glands ducting into the first part of
the spongy urethra there are also lots
of little urethral glands that ducked
into the spongy urethra along its length
that's the male urethra the female
urethra then is much shorter around four
centimeters long which is the reason why
women are much more likely to get
urinary tract infections than men it
runs from the bladder to the vestibule
and it runs anteriorly to the vagina it
runs directly and straight through the
perineal membrane and the pelvic floor
there is no internal urethral sphincter
in the female bladder
unlike the male bladder and there is an
external resource filter just like we
see in the in the male pelvis
controlling closing the urethra
similarly along the female urethra there
are a number of little tiny urethral
glands doc Dean's of urethra and these
arethe will glance seem to be involved
in in lubrication of this tube and some
of these are called para youthful glands
and these seem to be the female
equivalent of the prostate gland in
terms of lots of little paring arre
through glands and blood supply well
you've got to think of nearby arteries
the both urethras male and female are
supplied with blood by arteries of the
pelvis that sounds obvious but remember
the gonads aren't all right so in the
male
we have inferior vesicle arteries or
branches of so v zakone refers to the
bladder so there are artery supplying
blood to the bladder those inferior
vehicle arteries are supplying blood to
the inferior part of the bladder and
also to the urethra in the male the
rectum is nearly really nearby so middle
rectal arteries also supply blood to
parts of the urethra and then as the
urethra continues the dorsal artery of
the
penis is also going to supply blood to
the urethra along its length in the
female pelvis it's similar but different
the vagina is right next to the urethra
so the journal arteries also supply
blood to the urethra as do pudendal
arteries and what have you notice how
the rectum is much further away from the
urethra because the vagina is in the way
so the female urethra supplied with
blood by branches of vaginal arteries
and branches of the internal pudendal
artery and those arteries all come from
the anterior trunk of the internal iliac
artery supplying blood generally to the
the viscera of the pelvis the veins are
similar or the same going in the
opposite direction and the lymphatics
likewise which means that the lymphatic
drainage of the urethra is to lymph
nodes of the of the pelvis so generally
iliac lymph nodes or maybe deep inguinal
lymph nodes just think of your direction
of flow all right
lastly innovation well we're talking
about a sympathetic parasympathetic and
visceral afferent sensory stuff related
to the urethra both male and female
urethras receive nerves from the
pudendal nerve remember there's a
pudendal nerve but there are internal
and external pudendal arteries and the
difference is that the there are
plexuses there's a vizac physical plexus
pertaining to the bladder in the female
pelvis that sends branches to the
urethra and in the male there is a
prostatic plexus and that sends branches
to the urethra in the male visceral
afferent sensory nerves follow the
parasympathetic nerves back to the
spinal cord that levels s2 s3 and s4
parasympathetic uber so they're very low
down in the spinal cord they're not
going to the sympathetic visible so we
have looked at the male urethra and the
female urethra we've looked at the
differences in the similarities the male
urethra habit has a number of parts to
it and that internal urethral sphincter
is an interesting idea and the prostatic
part of the male urethra is the
with the most confusing bits aren't
really very important but if you look at
it in the textbook it kind of seems like
they are important so with a bit of
study hopefully that's not too difficult
to remember we've looked at the blood
supply through pelvic venous drainage
lymphatic drainage very pelvic and we've
talked about the the innovation alright
good
is there anything left in the renal
system that we haven't done I don't know
I have a look see you guys next week
then although in fact it won't actually
be next week because if you're watching
these at the time they go out I will be
in Austria next week but when I put this
out I will be back from Austria it's all
very confusing this temporal stuff
anyway see you sometime in the future
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