Description

Ureter, Urinary Bladder, and Male/Female Urethra

This video covers the anatomy and function of the ureter, urinary bladder, and male and female urethra, including their structures, layers, and clinical significance.

PS! At 6:23, I incorrectly stated that the Median Umbilical Ligament is a remnant of the umbilical arteries. It is, in fact, a remnant of the fetal urachus.

1. Ureter

• Function: Transports urine from the renal pelvis to the bladder via peristaltic movement.

Course of the Ureter:

• Enters the lesser pelvis and crosses structures:
  • In Males: Crosses the ductus deferens.
  • In Females: Passes between the broad ligament (Ligamentum Latum Uteri) and the cardinal ligament (Ligamentum Cardinale Uretri).
• Opens into the bladder as the ureteric orifices (Ostium Ureteris).

Parts of the Ureter:

• Abdominal Part (Pars Abdominalis).
• Pelvic Part (Pars Pelvica).
• Intramural Part (Pars Intramuralis).
• Diameter: 7-8 mm.

Narrowings of the Ureter:

• Upper: Junction with the renal pelvis.
• Middle: Line terminalis.
• Lower: Intramural part.

Layers of the Ureter Wall:

• Tunica Mucosa: Inner lining.
• Muscularis:
  • Lower 1/3: Three muscle layers (inner longitudinal, middle circular, outer longitudinal).
  • Upper 2/3: Two muscle layers (inner longitudinal, outer circular).
• Tunica Adventitia: Outer connective tissue.

2. Urinary Bladder (Vesica Urinaria)

• Function: Stores 250-500 ml of urine.
• Location: Empty bladder lies behind the pubic symphysis; a full bladder extends above it.

Parts of the Bladder:

• Apex of Bladder (Apex Vesicae).
• Body of Bladder (Corpus Vesicae).
• Fundus of Bladder (Fundus Vesicae).
• Trigone of Bladder (Trigonum Vesicae).
• Right and Left Ureteric Orifices (Ostium Ureteris Dextrum et Sinistrum).
• Internal Urethral Orifice (Ostium Urethrae Internum).
• Interureteric Crest (Plicae Interureterica).

Layers of the Bladder Wall:

• Tunica Mucosa: Lined with transitional epithelium.
• Tela Submucosa: Loose connective tissue; no folds in the trigone.
• Tunica Muscularis (Detrusor Muscle):
  • Inner longitudinal layer.
  • Middle circular layer (forms the internal urethral sphincter).
  • Outer longitudinal layer.
• Tunica Adventitia or Serosa:
  • Adventitia if facing the pelvis.
  • Serosa if facing the peritoneum.

3. Male Urethra (Urethra Masculina)

• Length: ~18-20 cm.
• Parts of the Male Urethra:
  • Prostatic Urethra (Pars Prostatica):
    • Contains the urethral crest, seminal colliculus, and prostatic utricle.
    • Receives openings of ejaculatory and prostatic ducts.
  • Membranous Urethra (Pars Membranacea):
    • Between the prostate and the bulb of the penis.
    • Surrounded by the external urethral sphincter.
  • Spongy Urethra (Pars Spongiosa):
    • Located inside the corpus spongiosum.
    • Receives the duct of the bulbourethral gland.

Narrowings of the Male Urethra:

• Internal Urethral Orifice.
• Membranous Part.
• External Urethral Orifice.

Enlargements of the Male Urethra:

• Prostatic Urethra.
• Spongy Urethra.
• Navicular Fossa.

4. Female Urethra (Urethra Femina)

• Length: ~4 cm.
• Location: Opens posterior to the clitoral glans.

Walls of the Female Urethra:

• Tunica Mucosa: Contains urethral lacunae.
• Tunica Muscularis:
  • Internal Urethral Sphincter.
  • External Urethral Sphincter.

5. Clinical Relevance

• Kidney Stones (Urolithiasis): Commonly lodged at ureter narrowings.
• Urinary Tract Infections (UTIs): More common in females due to shorter urethra.
• Benign Prostatic Hyperplasia (BPH): Can obstruct the prostatic urethra, causing urinary retention.

Sources:

• Biorender.
• University notes and lectures.

Transcript

Introduction
0:01
[Music]
0:04
what’s up
0:04
mediterra here let’s talk about the
0:06
anatomy of the urinary system
0:07
in this segment we will be talking about
0:09
the anatomy of the ureter the urinary
0:11
bladder and the urethra in both male and
0:13
female
0:14
so the urinary system consists of all
0:16
the organs involved in handling the
0:18
urine
0:19
and these are the kidneys the ureter the
0:21
urinary bladder and the urethra
0:24
in our last video we covered the anatomy
0:26
of the kidneys
0:27
now let’s do the rest of the urinary
0:28
system so in this video
0:30
our goal is to go through the functions
0:33
and the course of the e-reader
0:34
and then we’ll cover the parts and the
0:36
different constrictors or
0:38
narrowings the ureter has as well as the
0:40
layers of the ureteral wall
0:42
after that we will do the parts and the
0:44
layers of the urinary bladder
0:46
and then the general anatomy of the male
0:48
and female urethra
Functions of the Ureter
0:50
alright so here we see the anterior view
0:52
of the kidney
0:53
remember the kidneys have an area called
0:55
the helium and from the helium you will
0:58
find the renal pelvis coming out
1:00
and at the point of where the renal
1:02
pelvis ends
1:03
that’s where the ureter will start so
1:05
the urethra’s function is really only
1:07
leading the freshly made urine
1:09
from the kidneys all the way down to the
1:11
urinary bladder
1:12
one of the common misconceptions
1:14
regarding the ureter is that
1:16
people seem to think it’s just a tube
1:17
without any control of the urine
1:19
all it does is that it provides a flow
1:21
for the urine from the kidneys to the
1:23
urinary bladder
1:24
the ureter is actually a muscular tube
1:27
that transports the urine
1:28
through peristaltic movements as you see
1:30
here just like the intestines when they
1:32
move the content through contractions
1:35
the ureter does the same with the urine
1:37
and i’ll show you how when we go through
1:39
the walls of the ureter and the
1:40
constrictions we have
1:41
therefore the urine flow is not
1:43
continuous so the ureter
Course of the Ureter
1:45
can be roughly around 30 centimeters
1:48
long
1:49
and they both lie at the very back of
1:51
the abdominal cavity as you see here
1:53
and they lie right in front of the
1:55
surface major muscle
1:57
and when it reaches the terminal line of
1:59
the pelvis
2:00
it then enters the lesser pelvis and
2:02
from this point
2:03
it crosses some structures differently
2:05
in men and women
2:07
so in male it crosses the ductus
2:09
dividends
2:10
as you see here right before it enters
2:12
the urinary bladder
2:13
the adductor’s difference remember is
2:15
the duct that comes from the testes
2:17
of the male and then in female it gets a
2:19
little more complicated than that
2:21
so what do we see here we see the
2:23
urinary bladder we see the ureter
2:25
at the back and we’ll also see the
2:27
uterus and the uterine tubes or the
2:29
fallopian tubes
2:30
the ureter will pass between a ligament
2:33
you see here
2:34
called the broad ligament of the uterus
2:36
or ligamentum lotum uttari
2:38
which is a ligament that attaches the
2:41
lateral portions of the uterus
2:43
to the lateral pelvic wall as you see
2:45
here so
2:46
the ureter passes between this ligament
2:49
and
2:50
another ligament highlighted here in
2:51
green called the cardinal ligament of
2:53
the uterus
2:54
after that it enters the urinary bladder
2:57
so the cores differ a little bit in
2:59
male and female and then when the ureter
3:01
enters the urinary bladder
3:03
it enters as an orifice called the
3:05
uretric orifice
3:06
so that’s the general course of the
3:08
ureter
Parts of the Ureter
3:10
the ureter is divided into parts
3:12
according to its location
3:14
when the ureter is in the abdomen it
3:16
gets the name the abdominal part
3:18
which lies between the renal pelvis and
3:20
the terminal line of the pelvis
3:22
when the ureter is in the pelvis it gets
3:24
the name the pelvic part which ends at
3:27
the
3:27
urinary bladder and when the ureter is
3:29
in the wall of the urinary bladder
3:31
it gets the name the intramural part so
3:34
the ureter has three parts generally
3:36
abdominal part pelvic part and
3:38
intramural part
3:41
the ureter is usually between seven to
3:43
eight centimeters
3:44
in diameter but it has some narrowings
3:47
that decreases this diameter
3:49
and when the diameter decreases it gets
3:51
roughly around three to four millimeters
Constrictions of the Ureter
3:53
wide
3:54
so there are three narrowings or
3:56
constrictions the ureter has
3:58
the first one is the upper narrowing at
4:00
the junction between the renal pelvis
4:02
the middle one is at the linear
4:04
terminalis and the lower narrowing
4:07
is when the ureter is inside the wall of
4:10
the urinary bladder
4:11
so that was the narrowings of the
Layers of Ureter Wall
4:13
e-reader let’s now make a transverse cut
4:15
of the eraser
4:16
and look at the layers of the ureter
4:18
wall and to make this easier we will
4:20
line the external surface first
4:22
so the first layer is the tunica mucosa
4:24
which is the innermost layer
4:26
it’s smooth and contains transitional
4:28
epithelium
4:29
that are able to stretch and dilate when
4:32
the urine passes through
4:33
for the other layers we need to add a
4:36
line here in the middle
4:37
because the lower one-third of the
4:39
ureter will be different from the upper
4:41
two thirds of the ureter
4:43
so the lower third of the ureter is
4:46
going to have these glands present
4:48
in the taylor submucosa which is a layer
4:50
that contains loose connective tissue
4:52
along with blood vessels and nerves and
4:54
lymphatic tissue and then
4:56
under the taylor submucosa we have a
4:58
muscle layer called the tuning
5:00
chemiscularis
5:01
the muscle layer will be different in
5:03
the upper two thirds of the ureter
5:05
than the lower third the upper two
5:07
thirds of the ureter is going to have
5:09
two layers of muscle fibers
5:11
where the inner part are going to be
5:13
longitudinal muscle fibers
5:14
and the outer part is going to be
5:16
circular muscle fibers
5:18
and keep in mind that most tubes you
5:20
have in your body are going to consist
5:22
of circular and longitudinal muscle
5:23
fibers for the
5:24
peristaltic movements the lower third of
5:27
the ureter
5:28
differs in that it’s going to have three
5:31
layers of muscle fibers
5:33
the innermost is going to be
5:34
longitudinal muscle fibers
5:36
the middle part consists of circular
5:38
muscle fibers
5:39
and then the outer part will be
5:40
longitudinal muscle fibers
5:42
it’s different here because the closer
5:44
you get to the urinary bladder
5:46
the more it’s going to resemble the
5:48
urinary bladder
5:49
so the last layer is the outermost layer
5:52
which is going to be tunica adventitia
5:54
containing
5:54
strong fibrous connective tissue for
5:56
protection
5:58
so that was all for the anatomy of the
6:00
eurator
Urinary Bladder
6:01
now let’s continue and look at the
6:03
anatomy of the urinary bladder
6:05
now the urinary bladder is a sac that
6:07
stores urine
6:08
and its capacity really depends on the
6:10
size of the person
6:12
but in average it should be around 250
6:14
to 500 milliliters
6:16
all right so here we see the ureter and
6:19
here is the urinary bladder
6:21
and in the middle of the urinary bladder
6:23
you will find the median
6:25
umbilical ligament which during
6:27
embryonic life
6:28
used to be the umbilical arteries but
6:30
after birth
6:31
the umbilical arteries degenerates to
6:34
become the median umbilical ligament
6:36
without any proper functions in the body
6:38
but anatomically
6:39
it’s there attached to the urinary
6:41
bladder now the urinary bladder
6:44
is divided into parts the first part
6:46
closest to the median umbilical ligament
6:48
is the apex of the bladder the majority
6:51
of it
6:52
is the body of the bladder and then
6:54
posteriorly you will find the fundus of
6:56
the urinary bladder
6:57
alright so there are two general
7:00
conditions the urinary bladder can be
7:02
in it can either be empty or rather full
7:05
the empty urinary bladder is situated
7:07
behind the pubic symphysis as you see
7:09
here
7:10
and it has two surfaces it has an
7:12
anterior surface towards the symphysis
7:15
and a posterior surface towards the
7:17
peritoneum and there’s usually these
7:19
lateral margins that separates these two
7:21
surfaces
7:22
the full urinary bladder however has an
7:24
oval shape
7:25
as you see here and it lies above the
7:27
pubic symphysis
7:29
so this just shows you that the urinary
7:31
bladder isn’t always going to be located
7:33
right behind the pubic symphysis
7:35
now if you go back to this picture and
7:38
open it up
7:38
you’ll be able to see the right ureteric
7:40
orifice and the left ureteric orifice
7:43
which remember are the openings for the
7:44
ureters
7:46
and then down here is an opening for the
7:48
urethra called the internal urethral
7:50
orifice
7:51
and these three are going to form a
7:53
triangle called the trigone of the
7:55
urinary bladder which is an
7:56
area where the mucus fold is fused with
7:59
the muscle layer
8:00
now there’s also going to be a fold
8:02
between them between the two openings of
8:04
the ureters
8:05
called the interureteric crest now let’s
Layers of Urinary Bladder Wall
8:08
take a small piece of the urinary
8:10
bladder
8:11
and look at the histological picture of
8:13
it to understand the layers of the
8:14
urinary bladder
8:16
the urinary bladder is going to have a
8:18
tunica mucosa
8:20
a tls submucosa tunicum scolaris
8:23
and tunica adventitia or tunicacerusa
8:26
depending on which side you’re looking
8:27
at
8:28
so the tunica mucosa is a layer that
8:30
consists of transitional epithelium
8:32
and the upper layers of the cells are
8:34
called umbrella cells because they look
8:36
like the top part of the umbrella
8:38
in the relaxed state underneath the
8:41
epithelium you will find the lamina
8:42
propria
8:43
just like any other tunica mucosa in the
8:45
body and then the next layer
8:47
is the taylor submucosa containing loose
8:50
connective tissue
8:51
and you will notice that there are no
8:52
folds at the region of the trigon of the
8:55
bladder
8:55
because remember this triangle doesn’t
8:57
have a taylor submukusa
8:59
the tunica mucosa and the muscularis are
9:02
fused together in this area
9:04
next is the tunica muscularis which is
9:07
this thick layer
9:08
and it’s thick because it consists of
9:10
three muscle layers
9:12
it has an inner longitudinal layer a
9:14
middle
9:15
circular and an outer longitudinal layer
9:18
the middle circular
9:19
is going to form a sphincter at the
9:21
urethral orifice
9:23
called the inner urethral sphincter so
9:26
that is the tunica muscularis
9:28
the outermost layer is either going to
9:30
be tunicarosa
9:31
or tunic adventitia now what does that
9:34
mean
9:35
remember here is the peritoneum which
9:37
forms a serious coat around the organs
9:40
within the abdominal cavity
9:41
the surface that is not faced against
9:44
the peritoneum
9:45
is called tunica adventitia which
9:48
consists of dense
9:49
fibrous connective tissue while the
9:51
surface that faces the peritoneum
9:53
is called tunica serosa and notice that
9:56
when the urinary bladder is full
9:58
a larger portion of the urinary bladder
10:00
are going to be covered by the tunica
10:02
serosa
10:03
so that was the anatomy of the urinary
Anatomy of the Male Urethra
10:06
bladder
10:06
now let’s move under the urinary bladder
10:09
and cover the anatomy of the urethra
10:11
and remember that the urethra is
10:13
different in male and female
10:15
so we’ll start with the anatomy of the
10:16
male urethra first
10:18
all right so what do we see here we can
10:20
see the bladder
10:21
and the prostate under it we can see the
10:23
perineum which are muscles on the pelvic
10:26
floor
10:26
and then we can see the penis so the
10:28
urethra is the tube
10:30
under the urinal bladder that goes
10:33
within the penis
10:34
and it goes all the way from the
10:36
internal urethral orifice
10:38
to the external urethral orvis so the
10:41
whole urethra is about 15 to 22
10:44
centimeters long
10:45
and it’s about five to seven millimeters
10:47
in diameter
10:49
and it has three parts the part inside
10:51
the prostate
10:52
is called the prostatic urethra and it’s
10:54
about three centimeters long
10:56
and the part inside the perineum is
10:58
called the membranous urethra
11:00
which is roughly about one and a half to
11:02
two centimeters long
11:04
and then we got the spongy urethra which
11:06
is about 15 centimeters long
11:08
lying between the spongy parts of the
11:10
penis
11:11
let’s now go through each of these parts
11:13
and we will start with the prostatic
11:15
urethra
11:16
by looking from this perspective it will
11:18
look like this
11:19
so this is the posterior wall of the
11:21
urethra in male at the prostate region
11:24
first you will see a ridge called the
11:26
urethral crest
11:28
which is an elevated crest on the
11:29
posterior surface of the urethra
11:32
and then in the middle part there’s an
11:34
elevation formed by the
11:35
mucous membrane called the seminole
11:37
colliculus and
11:39
on the seminal colliculus you will find
11:41
the prostatic utricle
11:42
which is a remnant of the
11:44
parametronephric duct during development
11:46
which is now just a depressed fossa on
11:48
the seminal colliculus
11:49
and then on either side of it you will
11:51
find the openings for the ejaculatory
11:53
ducts
11:54
coming from the testes that secretes out
11:56
sperm into the urethra
11:58
and then on the sides there are many
12:00
small openings for the prostatic
12:02
secretion
12:03
called the prostatic ductals so that’s
12:05
this one
12:06
next we have the membranos urethra it
12:09
lies between the prostate
12:11
and the bulb of the penis and this part
12:13
is completely surrounded by the
12:15
sphincter
12:16
called the external urethral sphincter
12:19
so
12:19
that’s that one then the last part is
12:22
the spongy urethra
12:24
this part extends from the membranous
12:26
urethra
12:27
up here all the way to the external
12:29
urethral orifice
12:31
so the whole spongy urethra is located
12:34
inside the body of penis except the
12:36
upper part which is directly below the
12:39
perineum
12:40
and this part is only surrounded by
12:42
connective tissue
12:43
and then at the region of the bulb of
12:45
the penis the duct of the bilbo urethral
12:48
gland
12:48
is going to open up secreting liquid for
12:51
the sperm
12:52
and so the male urethra has three nerve
12:55
rings and three enlargements
12:57
the first narrowing is the internal
12:59
urethral orifice
13:01
the second one is the external urethral
13:03
orifice
13:04
and the last one is the narrowing at the
13:06
membranous urethra
13:08
the enlargements however are at the
13:10
prostatic urethra
13:12
right here then there’s the enlargement
13:14
at the region of the bulb of the penis
13:16
and then the third enlargement is at the
13:18
fossa called navicular fossa
13:20
as you see here now lastly let’s look at
13:23
the walls of the urethra
13:25
we have the tunica mucosa on the inside
13:27
which contains
13:28
urethral lacuna which are very small
13:31
openings
13:32
at which the urethral glands open up to
13:35
lubricate the surface
13:36
and then here in the navicular fossa the
13:39
mucus fold
13:40
forms a valve called the valve of the
13:42
navicular fossa
13:43
as you see here and it’s literally a
13:46
valve that prevents the backflow of
13:48
urine
13:49
so that’s the tunico mucosa the next
13:52
layer is called tunicomiscolaris
13:54
which is a muscle layer that forms
13:56
sphincters these
13:57
are the internal urethral sphincter and
14:00
the external urethral sphincter
14:02
the internal urethral sphincter is made
14:05
up of smooth muscle fibers
14:06
while the external one is made up of the
14:09
perineum
14:09
which are skeletal muscle fibers meaning
14:12
that this sphincter with skeletal muscle
14:14
fibers
14:15
is a voluntary type of sphincter so you
14:17
can voluntarily
14:18
close and open that sphincter so that’s
14:21
all i had for the male urethra
14:23
and now next we have the female urethra
Anatomy of the Female Urethra
14:26
and for orientation sake
14:28
the bladder is here and the vaginal
14:30
openings here
14:31
so the female urethra is this short tube
14:34
right here
14:35
which measures around two and a half to
14:37
four centimeters long
14:39
and about eight to twelve millimeters in
14:41
diameter
14:42
so it’s much shorter than in the male’s
14:44
urethra
14:45
but larger in diameter which is the
14:47
reason why the female urethra
14:49
may be prone to leakage of urine more
14:51
than male urethra however
14:53
we’re still going to have the same
14:54
structures as the male urethra
14:57
we’re basically going to have two
14:58
openings an internal urethral orifice
15:01
at the urinary bladder and an external
15:04
urethral orvis
15:05
which lies roughly about two centimeters
15:07
behind the glans clitoris
15:09
which is the head of the clitoris
15:11
peeking out from the female genitalia
15:13
so now let’s look at the walls of the
15:16
urethra as well
15:17
again it’s more or less going to look
15:18
similar to the male syritra
15:20
we’re going to have the tunica mukosa
15:22
with small openings called urethral
15:24
lacuna
15:25
at which the urethral glands open up
15:27
lubricating the surface
15:29
we’re also going to have the tune comes
15:30
scolaris which forms two sphincters
15:33
the internal urethral sphincter which
15:36
lies at the border between the bladder
15:38
and the urethra
15:39
and we’re also going to have the
15:40
external urethral sphincter
15:42
at the perineum of the female so that
15:45
was everything i had for the anatomy of
15:47
the ureter
15:48
the urinary bladder and the urethra if
15:50
you found this video helpful please put
15:52
a like share comment whatever you find
15:53
convenient to you
15:54
see you next time