Anatomy of the bladder, urethra and micturition Flashcards
(102 cards)
1
Q
where is the bladder located?
A
in the pelvis
2
Q
where do the ureters enter the pelvis?
A
pelvic inlet at the sarcoiliac joint
ureters pass anterior to bifurcation of common iliacs and continue down the pelvic wall to join the base of the bladder
3
Q
urinary bladder
A
extraperitoneal structure
4
Q
bladder in empty state
A
superior border
superior margin of pubic bone
5
Q
bladder in full state
A
extends superiorly encroaching on abdominal cavity but remains retroperitoneal
6
Q
where can the bladder rupture?
A
into peritoneum or extraperitoneally
7
Q
urethra course
A
passes through pelvic floor
8
Q
bladder in children
A
has a much higher position in the abdomen
it descends into the pelvis by the end of puberty
9
Q
shape of bladder
A
pyramidal shape
10
Q
base of bladder
A
posterior
11
Q
apex of bladder
A
anterior
urachus is present - remnant of allantois
12
Q
surfaces of bladder
A
left and right inferolateral surfaces
superior surface
13
Q
where in the bladder do the ureters join?
A
pelvoureteric junction
upper corners of base of bladder
14
Q
where does the urethra drain from?
A
the inferior portion of the bladder base
15
Q
what is anterior to the bladder?
A
pubic symphysis
retroperitoneal space
16
Q
what is posterior to the bladder?
A
vaginal and cervix in females
vas deferens and seminal vesicles - lateral as well in males
rectum
17
Q
what is lateral to the bladder?
A
pelvic floor muscles
levator ani
obturator internus
18
Q
what is superior to the bladder?
A
peritoneum - covers the dome
intestines
intra-peritoneal contents
uterus in females
19
Q
what are the pelvic floor muscles?
A
pubococcygeus puborectalis iliococcygeus all make up levator ani complex obturator internus coccygeus makes up rest of pelvic floor
20
Q
what muscles make up the levator ani?
A
pubococcygeus
iliococcygeus
puborectalis
21
Q
bladder wall
A
made up of detrusor muscle
22
Q
what is the detrusor muscle?
A
smooth muscle
23
Q
sympathetic control of bladder
A
detrusor muscle relaxed during the filling phase of micturition via sympathetic branches
24
Q
where do the sympathetic branches of the bladder originate?
A
thoracic and lumbar spinal cord
25
parasympathetic control of bladder
contracts when urinating via parasympathetic branches
26
where do the parasympathetic branches of the bladder originate?
sacral spinal cord
27
arrangement of detrusor muscles
in loops around ureteral openings to prevent reflux of urine back into ureters
28
internal urethral sphincter
thickening of detrusor muscle around bladder neck
| only in males
29
external urethral sphincter
present in both sexes
at pelvic diaphragm
skeletal muscle
30
what is the trigone?
smooth triangular area between the internal urethral sphincter and 2 openings from the ureters
31
what is the role of the trigone?
highly sensitive to expansion and when stretched sends signals to the brain that the bladder is filling
as it stretches signals become stronger and more frequent
32
where is the neck of the bladder
inferior most point of bladder
at urethral opening
where the bladder meets the 2 inferolateral surfaces
most fixed part of bladder
33
what holds the neck of the bladder in place?
a pair of tough fibromuscular bands which connect it and the proximal part of the urethra to the pubic bone
34
female fibromuscular bands of bladder
pubo-vesical ligaments
35
male fibromuscular bands of bladder
pubo-prostatic ligaments
| because they blend with the fibrous capsule of the prostate that also surrounds the urethra and bladder neck
36
what else holds the bladder in place?
perineal membrane
levator ani muscle
pubic bone
37
what arteries supply the bladder?
superior and inferior vesical arteries
| branches of internal iliac artery
38
what does the superior vesical artery supply?
anterior and superior portion of bladder
39
blood supply to bladder in females?
inferior vesical arteries largely replaced with the vaginal arteries
40
venous drainage of bladder
follows arterial supply
vesical venous plexus
drains into internal iliac veins
41
what lines the bladder and ureters?
transitional epithelial cells
42
bladder cancer
caused by transitional cell carinomas
43
what lines the urethra?
proximal - as it exits bladder transitional epithelium continues
becomes pseudostratified columnar then stratified squamous epithelial cells near the external urethral orifice
44
other cells within urethra
mucus secreting urethral glands that help protect the epithelium from corrosive urine
45
what is the urethra?
muscular tube that conveys urine from bladder to outside
| in males it carries semen during ejaculation
46
female urethra
short
4cm
slightly curved
47
what does the female urethra pass through
pelvic floor into perineum
deep perineal pouch - where the external urethral sphincter is
perineal membrane
opens in the vestibule between the labia minora
48
male urethra
longer
up to 20cm
bends twice along course when penis is flaccid
49
course of male urethra
```
begins at base of bladder
passes inferiorly
through prostate
deep perineal pouch
then perineal membrane
enters root of penis
```
50
parts of male urethra
```
4 parts
preprostatic
prostatic
membranous
spongy - within penis
```
51
preprostatic part of urethra
short within wall of bladder
associated with internal urethral sphincter - important for continence and preventing retrograde ejaculation into bladder
52
prostatic part of urethra
passes through prostate
| where ejaculatory ducts and seminal vesicles open into urethra
53
membranous part of urethra
passes through deep perineal pouch
| location of external urethral sphincter
54
spongy part of urethra
surrounded by erectile tissue and muscles of penis
| forms a bulb at the end of penis
55
bulb at end of penis
navicular fossa
56
what muscles control the urethra?
internal and external urethral sphincter in males and just the external urethra sphincter in females
57
internal urethral sphincter
```
males only
junction of bladder and urethra
continuation of detrusor muscle
smooth muscle so involuntary
prevents reflux during ejaculation
```
58
external urethral sphincter
```
located in deep perineal pouch
part of pelvic floor
inferior to prostate in males
skeletal muscle so voluntary
innervated by pudendal nerve
```
59
pudendal nerve
main nerve of perineum
60
nerve roots of pudendal nerve
S2-4
61
course of pudendal nerve
through both greater and lesser sciatic foramen of pelvis
| through pudendal canal
62
branches of pudendal nerve
into perineal interior rectal and dorsal nerve of penis and clitoris in females
63
sensory supply of pudendal nerve
external genitalia
anus
perineum
64
motor supply of pudendal nerve
pelvic floor muscles
external urethra sphincter
anal sphincter
65
pudendal nerve block
done for episiotomy
66
when will the desire to urinate begin?
150ml as bladder wall is stretched
67
law of laplace
as the volume of the urine increases the bladder is able to maintain constant pressure as the bladder expands to accommodate more urine - due to Laplace's law
68
what causes the law of laplace?
relaxation of the detrusor muscle increases the radius and so despite the volume of urine increasing there is minimal increase in pressure to 400ml
69
what happens in the bladder when filled over 400ml
there is a high pressure increase
| resulting in a strong urge to urinate
70
how to measure pressure and volume in bladder
cystogram
71
phases of micturition
2 phases:
bladder filling - filling phase
bladder emptying - voiding phase
72
what happens in the filling phase of micturition
pressure remains low due to detrusor relaxation as the bladder fills - law of laplace without increase in sensation to urinate
stretch receptors in bladder fire low level action potentials via sensory neurons to sacral part of spinal cord as it fills and stretches
causes detrusor muscle relaxation to allow the bladder to stretch and fill by excitement of sympathetic innervation and inhibiting parasympathetic neurons
sympathetic neurons cause contraction of bladder neck and internal urethral sphincter
stretch
contraction of external urethral sphincter via excitation of Onuf's nucleus and the pudendal nerve
73
what is Onuf's nucleus?
group of neurons in the anterior horn of the sacral region of the spinal cord - origin of pudendal nerve
74
voiding phase of micturition
when the bladder is almost full
afferent signals from sensory neurons from stretch receptors increase so you become consciously aware of the need to urinate as they activate the pontine micturition centre in the brainstem
continue to increase
when you are ready to urinate the pontine micturition centre fires signals to excite sacral parasympathetic neurons causing contraction of detrusor and increases pressure inside the bladder
overcomes sympathetic control of internal sphincter in males
sends signals to inhibit onuf's nucleus to relax the external urethral sphincter via pudendal nerve
75
inhibiting urination
sympathetic innervation to internal urethral sphincter in males can prevent urination until the parasympathetic NS fired enough to overcome it
76
post-micturition - emptying of the urethra
in females the urethra is emptied by gravity
| in males it is emptied by bulbospongiosus muscle contraction
77
automatic bladder reflex
in babies
stretching of the bladder due to filling causes it to contract under reflex control
internal sphincter in males relaxes
urine moves down urethra
can be learnt to be suppressed by potty training
78
overactive bladder
involuntary muscle contraction - response to distension
urgent uncontrollable need to urinate even if bladder is not full
causes incontinence and frequency
79
what causes an overactive bladder?
infection
medications
caffeine
alcohol
80
treatment for overactive bladder
many
| pelvic floor muscle exercises
81
neurogenic bladder causes
spinal injury
MS
stroke
neurodegenerative diseases
82
types of neurogenic bladder
spastic and flaccid
83
spastic bladder causes
upper motor neuron deficit
| injury above T10
84
flaccid bladder causes
lower motor neuron lesion
| peripheral nerves effected
85
mixed neurogenic bladder
spinal cord injury patients
monitored with ultrasound
needs self-catheterisation or suprapubic catheter
86
what happens with a spastic bladder?
```
hyperreflexive
detrusor and sphincter dyscoordination
urinary retention
small bladder
increased tone
```
87
what happens with a flaccid bladder?
hypotonic
detrusor doesn't contract
large bladder
88
supra-pubic catheter
permanent or semi-permanent bypass to drain bladder drainage
89
passage of supra-pubic catheter
passed through anterior abdominal wall
superior and medial to pubic symphysis
to anterior aspect of bladder
90
indications for suprapubic catheterisation
neurological cause preventing urination
physical cause - blockage e.g. cancer
trauma to urethra
physical or neurological deficits - management
91
bladder rupture
significant trauma
motor vehicle crash
most common type is extraperitoneal rupture within the extraperitoneal space and leakage of contents
92
what causes extraperitoneal bladder rupture?
pelvic fracture
| penetrating injury
93
management of extraperitoneal bladder rupture?
conservative
catheter
bladder heals itself
94
what are the types of bladder ruptures ?
extraperitoneal
intraperitoneal
combined
95
intraperitoneal bladder rupture
less common
| leakage of bladder contents into peritoneal cavity
96
causes of intraperitoneal bladder rupture
direct blow to bladder in distended state
97
treating intraperitoneal bladder rupture
requires surgical repair
98
urethral injury
more common in males
99
types of urethral injury
complete rupture
partial tear
anterior or posterior classification in males
100
anterior urethral injury
penile/ bulbar
straddle injury
compressed against pubic bone
isolated injury
101
posterior urethral injury
membranous/ prostatic
crushing force from motor vehicle accident
shearing, blunt trauma or straddle injury
associated with fractures and bladder injury
102
causes of urethral injury
blunt trauma - straddle injury
motor vehicle accidents
iatrogenic - from catheterisation
penetrating trauma
