Gross Anatomy & Histology of the Lower Urinary Tract Flashcards
What is the urinary bladder?
A three sided pyramid-like muscular organ with apex and base.
Where is the urnary bladder located?
Within the pelvic cavity just below the peritoneum.
Where does the bladder lie when empty?
In the lesser pelvis posterior to the pubic symphysis
Where does the bladder go when it gets full?
It expands and ascends into greater pelvis up to the level of the umbilicus
How does the urinary bladder ascend into greater pelvis when full?
Parietal peritoneum lining anterior abdominal wall is loose which allows it to be pushed upward
What are the surfaces of the bladder?
Superior surface which is covered by the peritoneum.
2 inferolateral surfaces is separated from superior surface by lateral border
What are the borders of the urinary bladder?
One anterior border (Separates both inferolateral surfaces anteriorly)
One posterior border (separating superior surface from the base of the bladder)
Two lateral borders (seperate inferolateral surfaces from the superior surface)
What is the apex of the bladder?
provides attachment to median umbilical ligament (fibrous remnant of the uracus/allantois) and medial umbilical ligament (Remnant of feotal umbilical artery proximal part will remain open in adults becoming a division of internal iliac artery and distal part becomes a ligament after becoming fibrotic)
What is the difference between median and medial umbilical ligaments?
Median ligament is the fibrous remnant of the uracus/allantois. Unpaired
Medial ligament is the remnant of feotal umbilical artery proximal part will remain open in adults becoming a division of internal iliac artery and distal part becomes a ligament after becoming fibrotic. Paired.
What does the median umbilical ligament do?
It attaches to apex of the bladder
Which way does the apex of the bladder point?
Towards the pubic symphysis
What does the base of the urinary bladder look like?
Triangular in shape and directed posteroinferiorly.
What structures connect to the base of the bladder and how?
The superolateral angles are joined by the ureters while the inferior angle gives rise to the neck of the bladder and the urethra.
What is the upper part of the base covered with in males?
Peritoneum
What is the internal urethral orifice?
The opening of the urethra
Where is the neck of the bladder?
It is located at the point where the inferolateral surfaces and the bladder base meet at the neck.
It rests on the upper surface of the prostate
What happens at the bladder neck?
The bladder is pierced by the urethra.
Where does the neck of the bladder rest in females?
Neck is related to endopelvic fascia which fixes the neck of the bladder.
What is the muscular coat of the bladder called?
Detruser muscle
What does the bladder inner surface look like?
It is thrown into folds called ruggae which become flat when bladder is full.
The trigone area is completely flat
What is the trigone?
Smooth shaped triangular area on the base of the bladder.
What supports the neck of the bladder?
The superior surface prostate in males
In males the puboprostatic ligament (forms slings around the prostate)
In females the pubovesical ligament (forms slings around the neck)
What is the bladder bed?
Refers to structures related to inferolateral surface and anterior border
What covers bladder superiorly to fix it in place?
Visceral peritoneum
What fixes the bladder in place?
Visceral peritoneum superiorly
Endopelvic fascia inferolaterally (separates bladder from obturator internus and levator ani)
Pubovesical ligament in females and puboprostatic ligament in male
What other structures are related to the superior surface of the urinary bladder?
The loops of the ileum
What is the space between pubis and bladder called? What is it filled with?
Retropubic space which is filled with fat
What structures are related to the base of the urinary bladder?
Posteriorly:
Rectum
Rectoprostatic fascia
Rectovesical pouch
Ureter and vas deferans posteriorly
Inferiorly
Prostate
Endopelvic fascia
What does the apex of the bladder rest on?
The pubic symphysis
What direction does the uterus point?
anteverted and lying on the superior border of the bladder
What structures lie posterior to the bladder in females?
Anterior fornix of the vagina
Vagina
Uterus
Where does the neck rest in females?
Endopelvic fascia
Pupovesical ligament
Urogenital diaphragm
What structures are related to bladder base in males?
Rectovesical pouch
Ureter, ductus deferens, and seminal vesicles
What structures are related to bladder base in females?
Ureter
Anterior vaginal wall and anterior fornix of vagina
What structures are related to bladder neck in males?
Prostate gland
What structures are related to bladder neck in females?
Endopelvic fascia
What structures are related to superior surface of bladder in males?
Covered by peritoneum
Peritoneal cavity containing loops of ileum
What structures are related to superior surface of the bladder in females?
Covered by peritoneum
Vesicouterine pouch
Peritoneal cavity containing loops of ileum
Body of the uterus
What structures are related to the inferolateral surface and anterior border of the bladder in males?
Retropubic space and pubic symphysis
Puboprostatic ligament
Levator ani
Obturator internus
Endopelvic fascia
What structures are related to the inferolateral surface and anterior border of the bladder in females?
Retropubic space and pubic symphysis
Pubovesical ligaments
Levator ani
Obturator internus
Endopelvic fascia
What is the structure of the urethra?
Lots of elastic fibrous tissue (fibromuscular tube) extending from the internal urethral orifice to the external urethral orifice
What is the wall of the urethra lined with?
Mucous membrane and a thick layer of longitudinal smooth muscle (in females)
What is the difference between the urethra in males and in females?
In males the urethra is
longer and has structures along it. External urethral sphincter present in males right after the prostate.
Female urethra is shorter and thicker and is surrounded by
How long is the urethra in males typically?
about 18cm in length
How many regions is the male urethra divided into? What are they?
4 regions:
Preprostatic urethra passes through neck of the bladder
Prostatic urethra Passes through prostate
Membranous urethra pass through the urogenital diaphram
Spongy (penile) urethra passes through length of the penis (longest part of urethra)
Describe the Intramural or preprostatic urethra:
0.5cm to 1.5cm in length and is the shortest part of the male urethra.
It extends from the internal urethral orifice and runs vertically through the bladder neck
It is surrounded by the internal urethral sphincter
Describe the prostatic urethra:
Prostatic urethra is the most dilated part of the male urethra
2.5cm in length
It has a longitudinal ridge on its posterior wall called the urethral crest With a prostatic sinus on each side of the ridge
2 ejaculatory ducts open on the edge
Prostatic utricle opens in the middle of the urethral crest it is the remnant of embryonic uterovaginal canal it is homologous to the uterus and vagina in females
What happesn at the prostatic sinus?
Opening of prostate into the urethra happens here as well as opening of the ejaculatory ducts
Describe the membranous urethra:
Intermediate part of urethra which is 1.5cm long
It is the narrowest part of male urethra after the external urethral orifice
Membranous urethra lies within the urogenital diaphragm
It is surrounded by the external urethral sphincter and the deep perineal pouch
Describe the penile urethra:
15cm in length and is the longest part of the male urethra
Surrounded by erectile tissue
Bulbourethral glands open into proximal part of penile urethra
Distal part of urethra within the glans penis is dilated, it is called the navicular fossa
External urethral meatus is the narrowest part of the entire urethra
What sphincters are present in the female urethra?
Internal urethral sphincter and represents thickening of detruser muscle in the neck of the bladder.
External urethral sphincter surrounds middle part of the external urethral sphincter
Describe the female urethra?
Short (and about 3 - 4 cm long)
Traverses pelvic floor and urogenital diaphragm
Ends at the external urethral orifice
Upper part surrounded by internal urethral sphincted
Middle part surrounded by external urethral sphincter
What structure is related to the female urethra?
Female urethra descends inferiorly and is bound to anterior wall of vagina.
What structures does the female urethra pass through on its way out?
Female urethra traverses urogenital diaphragm
Pierces perineal membrane
Endopelvic fascia
Opens into the vestibule of the vagina
What is the internal urethral sphincter also called?
Sphincted vesicae
What is the internal urethral sphincter made of?
Smooth muscle at neck of bladder becomes thick forming internal urethra
What does the internal urethral sphincter do in males?
Contracts during ejactulation and is autonomically controlled during urination.
What does the external urethral sphincted do?
Can be controlled consciously due to somatic innervation by pudendal nerve and so it allows conscious control of urination.
What are the differences between internal and external urethral sphincter?
Internal urethral sphincter surrounds internal urethral orifice, contains smooth muscle and is innervated by sympathetic fibers and is involuntary.
External urethral sphincter surrounds membranous part of urethra, is derived from sphincter urethrae muscle within deep perineal pouch and is innervated by somatic fibers making it voluntary
Which lymphatics drain the urinary bladder?
Lymphatic vesseks from superolateral aspect of the bladder pass to external iliac lymph nodes
Lymphatics from fundus and neck of bladder pass to internal iliac lymph nodes
Some vessels from the neck of the bladder drain into the sacral or common iliac lymph nodes
What arteries supply the bladder?
Superior and inferior vesical arteries
Obturator, inferior gluteal, uterine, and vaginal arteries
What arteries supply the bladder?
Superior and inferior vesical arteries
Obturator, inferior gluteal, uterine, and vaginal arteries
Which veins drain the bladder?
Vesical venous plexus
What plexus and nerves supply the sympathetic fibers to the bladder? What is the resulting effect?
The hypogastric plexuses and nerves.
They are inhibitory to detruser muscle and motor to the internal urethral sphincter
Where do the detruser muscle and internal urethral sphincter get their parasympathetic supply? What is the resultant effect?
Pelvic splanchnic nerves and the inferior hypogastric plexus.
They are motor to detruser muscle and inhibitory to the internal urethral sphincter
Which spinal segments does the bladder receive sympathetic innervation?
T11 - L2
Which spinal segments does the bladder receive parasympathetic innervation?
S2 - S4
Where does the bladder recieve somatic nerve supply and waht is the resultant effect?
Pudendal nerve which is motor to the external urethral sphincter and voluntary
What spinal segments provide the somatic nerve control of the bladder?
S2 - S4
What does autonomic supply do to the bladder and urethra?
When bladder is empty it must be relaxed and so it receives sympathetic innervation.
Preganglionic neurons are located in lateral horn in grey matter of T11 - L2. Postganglionic fibers supply detrusor muscle and internal urethral sphincter and they inhibit contraction while keeping the internal urethral sphincter contracted.
Parasympathetic fibers causes contraction of detruser muscle and relaxation of sphincter.
What is the other pain line?
Thoracic pain line. Any structure above this line also follows the parasympathetic nerves
What is the other pain line?
Thoracic pain line. Any structure above this line also follows the parasympathetic nerves
Where can pain from gall bladder be referred to?
the right shoulder
What are the layers of tissue in the urinary bladder?
Mucosa (contains transitional epithelium 6 layers when bladder is empty and 3 when full)
Muscularis propria
Adventita (Dense irregular connective tissue and areolar connective tissue)
What kind of muscles are present in the muscularis propria of the bladder?
3 layers of smooth muscle (outer longitudinal, middle circular, inner longitudinal)
Inner and outer longitudinal muscle
Middle circular muscle
What muscle layer forms the internal urethral sphincter?
At the neck of the bladder the circular fibers are thickened to form the internal urethral sphincter
What is the difference between adventitia and serosa?
Serosa is used for intra peritoneal structures and adventitia for retroperitoneal structures
What are folds of the bladder called?
rugae
What does transitional epithelium refer to?
There are 3 cell types: Umbrella cells, intermediate cells, and basal cells. Umbrella cells can change their shape and become flat when distended and rounded or cuboidal when empty. Intermediate cell layer has 5 layers and when distended it becomes one layer.
The ability for cells to accommodate to the changes in shape make the epithelium transitional
What are the layers of the male urethra?
Epithelium
Lamina properia
Muscularis propria
How does the male urethral epithelial layer change along its length?
Intramural and prostatic urethra contains transitional epithelium
Membranous urethra contains stratified pseudostratified columnar epithelium (unique epithelium not seen in many tissue only in urethra and some exocrine glands)
Penile urethra contains stratified pseudostratified columnar epithelium until the navicular fossa.
External urethral orifice and navicular fossa are lined by stratified squamous epithelium.
What does the lamina propria in the urethra contain?
mucous secreting urethral glands as well as ducts for bulbourethral glands
What muscles are contained within the muscularis propria?
Inner longitudinal and outer circular in prostatic and membranous urethra
No smooth muscle layers in penile urethra
Is there an adventitia surrounding the urethra?
No due to presence of other structures
What are the layers surrounding the female urethra?
Adventitia (proximal part has transitional epithelium distal part surrounded by
Lamina propria
Muscularis propria
Mucosa
What does female urethral epithelium consist of?
Transitional epithelium in the proximal part
Distal part contains stratified squamous epithelium and in some areas stratified columnar epithelium
What does the female urethral lamina propria consist of?
Thin layer comprises of urethral glands and paraurethral glands
What does the female urethral muscularis propria consist of?
Inner longitudinal and outer circular smooth muscle
Middle part is surrounded by skeletal muscle
What does the adventitia in the female urethra do?
Fuses with surrounding structures
What is the clinical significance of female urethra?
Female urethra can be easily dilated without injury so catheters and cystoscopes is easier in females than in males due to presence of elastic tissue and smooth muscle
