Case 8 Anatomy Flashcards
where is the empty bladder located in the adult? what happens as it fills? what about in children?
- In the adult the empty bladder is located entirely within the pelvis
- As the bladder fills it ascends into the greater pelvis where it lies within the extraperitoneal fascia of the abdominal wall
- It should be noted that in the infant and young child the bladder projects into the abdomen even when empty
when a patient has urinary retention, how can the access to the bladder be achieved?
through the hypogastric region of the abdominal wall
what is the bladder surrounded by?
endopelvic fascia
what does the endopelvic fascia consist of?
loose, areolar, fatty connective tissue that is packed between adjacent structures
what are the different parts of the bladder?
apex, base (fundus) (inferoposterior), body, superior surface, neck, and two inferolateral surfaces
where does the apex of the bladder lie?
anteriorly, behind the upper margin of the symphasis pubis
what is the apex attached to the umbilicus by?
the median umbilical ligament
where does the base/fundus of bladder face? what shape?
- faces posteriorly
- triangular in shape
- slightly convex
where is the body of the bladder located?
between the apex and the base
what is the superior surface covered in? where is it?
- covered with peritoneum
- bulges into the abdominal cavity when distended
what is the neck of the bladder held in position by?
- by the puboprostatic ligament (in males)
- by the pubovesical ligament (in females)
what does the inferolateral surface of the bladder lie adjacent to?
to the pubic bone and the retropubic fat pad
which relations in the bladder are the same in both males and females?
anterior and lateral relations
what are the anterior relations of the bladder?
- Symphasis pubis
- Anterior abdominal wall
- Retropubic fat pad
what are the lateral relations of the bladder?
- Obturator internus muscle
* Levator ani muscle
what are the superior relations of the bladder in female and male?
female:
• Body of the uterus
• Uterovesical pouch (directly above the bladder)
male:
• Coils of ileum
• Sigmoid colon
• Peritoneal cavity
what are the inferior relations of the bladder in the female and male?
female:
• Urogenital diaphragm
male:
• Prostate gland
what are the posterior relations of the bladder in the female and male?
female:
• Vagina
male: • Vas deferens • Rectum • Rectovesical pouch • Seminal vesicles
what are the layers of the bladder wall?
same four layers as that of the ureter:
- epithelium
- lamina propria
- muscularis
- adventia
(epithelium, lamina propria and muscularis mucosae = mucosa)
describe the internal surface of the bladder
- The epithelium and underlying lamina propria are loosely connected to the muscular layer of the bladder
- This allows the mucosa to be thrown into folds when the bladder is empty and to flatten out as the bladder fills
- However, one area on the base of the bladder always appears smooth because the mucosa is firmly attached to the underlying muscle
- Smooth region = trigone
describe the trigone
- Each of the three angles of the triangle presents a small ostium: two superiorly and the one inferiorly
- The ureters open into the bladder at the superior openings of the trigone
- The urethra opens into the bladder at the inferior opening of the trigone
what does the muscular coat of the bladder consist of?
three interlacing layers of smooth muscle
what is the muscle of the bladder?
detrusor
what are the muscle fibres of the neck continuous with in males and females?
- In females the muscle fibres of the neck are continuous with the muscle fibres of the urethra
- However, in males the muscles fibres are continuous with the fibromuscular tissue of the prostate
what prevents reflux back into ureter?
- In order to prevent reflux of urine from the bladder to the ureter, the ureters pass obliquely through the detrusor muscle on their way to the ureteric orifices of the trigone
- In addition, fibres of the detrusor muscle encircle the ureteric orifices and these tighten when the bladder contracts
what is the blood supply of the bladder?
bladder receives arterial blood from the superior vesical arteries and the inferior vesical (males) or vaginal arteries (females)
where do the superior vesical, inferior vesical and vaginal arteries arise from?
the internal iliac artery
what is the venous drainage of the bladder?
vesical venous plexus
where does the vesical venous plexus drain into?
internal iliac vein
in the male, what does the vesical venous plexus communicate with?
the prostatic venous plexus
what is the lymphatic drainage of the bladder?
- Lymph from the bladder drains to several groups of lymph nodes
- External iliac nodes = superolateral aspect
- Internal iliac nodes = posterior surface and neck
- Sacral or common iliac nodes = some areas of the neck
what is the bladder innervated by?
the autonomic nervous system
via what does the bladder mainly receive nerve fibres from?
the inferior hypogastric plexus
what is the function of the sympathetic and parasympathetic nervous system supply of bladder?
- Parasympathetic innervation is thought to be the major controller of bladder filling and emptying
- Parasympathetic fibres provide motor innervation to the detrusor muscle and inhibitory fibres to the internal sphincter
- Sympathetic fibres may be inhibitory to the detrusor muscle and provide motor innervation to the internal sphincter
- However, it is thought that sympathetic innervation is mainly responsible for vasomotor function in the bladder
PNS
- fibres transmitted in what
- preganglionic fibres arise from where
- where are postganglionic nerve cell bodies located
- what do fibres pass through
- Fibres transmitted in the pelvic splanchnic nerve
- Preganglionic fibres arise from the spinal cord segments S2-4
- Postganglionic nerve cell bodies located in the bladder wall
- Fibres pass through the inferior hypogastric plexus without synapsing
SNS
- fibres transmitted in what
- preganglionic fibres arise from where
- where do the preganglionic fibres terminate
- where are the postganglionic nerve cell bodies located
- Fibres transmitted in the lumbar splanchnic nerve
- Preganglionic fibres arise from the spinal cord segments T11-L2 (or 3)
- Preganglionic fibres terminate in the inferior hypogastric plexus
- Postganglionic nerve cell bodies located in the hypogastric plexus
what is the sensory information from the bladder concerned with?
reflexes or pain
what do the afferent reflexes follow the course of?
the parasympathetic fibres
describe the route of transmission of pain
- In order to understand the route of transmission of pain sensation from the bladder you need to understand the concept of the pelvic pain line
- Pelvic organs that are in contact with the peritoneum are said to be above the pelvic line whilst structures that do not contact the peritoneum are said to be below the pelvic pain line
- Visceral afferent information from structures above the pelvic pain line follows the course of the sympathetic fibres
- Visceral afferent information from structures below the pelvic pain line follows the course of the parasympathetic fibres
what is more consciously perceived, pain from above or below the pelvic pain line?
above
where is the pelvic pain line in terms of the colon?
midway along the length of the sigmoid colon
what do visceral afferents for pain from different aspects of the bladder follow the course of?
- Visceral afferents for pain from the inferolateral surface of the bladder follow the course of parasympathetic fibres
- Visceral afferents for pain from the superior surface of the bladder follow the course of sympathetic fibres
- Visceral afferents for pain from the bladder neck follow the course of parasympathetic fibres
how long is the female urethra?
not approximately 4 inches long (it’s about 1.9 inches / about 4 cm)
the axis of the female urethra lies parallel to that of the vagina and passes with it through what?
the pelvic diaphragm, external urethral sphincter and perineal membrane
what are the paraurethral glands and what are they homologous to in males? what are bulbourethral gland homologous to in females?
- The paraurethral glands, which open into the sides of the external urethral meatus, are not homologues to the bulbourethral glands of the male (may be homologous to the prostate gland)
(the bulbourethral gland in males is homologous to Bartholin’s glands in females)
how long is the male urethra?
approx. 20 cm long
where does the urethra extend from and to?
the internal urethral orifice to the external urethral orifice which is located on the tip of the glans penis
what are the four parts of the male urethra?
intramural, prostatic, intermembranous and spongy
intramural prostate
- extends from where
- what surrounded by
- Extends through the neck of the bladder
* Surrounded by the internal urethral sphincter
what is the shortest component of the urethra?
intramural
prostatic urethra
- what merges here
- what opens into this part
- what does the posterior wall display
- Urinary and reproductive tracts merge in this part
- The ejaculatory ducts open into this part of the urethra
- The posterior wall displays the prominent urethral crest
what is the widest and most dilated part of the urethra?
prostatic urethra
intramembranous urethra
- what does it pass through
- what does it penetrate
- what is it surrounded by
- Passes through the deep perineal pouch
- Penetrates the perineal membrane
- Surrounded by the external urethral sphincter
what is the narrowest and least distensible part of the urethra?
intermembranous urethra
spongy urethra
- what opens into this part
- what does it present - what is this called
- what is it surrounded by
- The bulbourethral glands open into this part
- Presents a dilated section, the navicular fossa (located at glans penis portion – essentially the part right before the external urethral orifice)
- Surrounded by the corpus spongiosum of the penis
what is the longest secretion of the male urethra?
spongy urethra
what is the blood supply of the urethra?
- The proximal part of male urethra is mainly supplied by the inferior vesical artery but receives some blood from middle rectal artery
- The vaginal artery supplies the proximal part of the female urethra
- The internal pudendal artery (branch of internal iliac artery) supplies the distal part of the male and female urethras
where does most lymph from the female urethra drain into?
into the sacral and internal iliac lymph nodes but some vessels drain into the inguinal lymph nodes
where does most lymph from the male urethra drain into?
- In the male, most lymph from the urethra drains into the internal iliac nodes but some drains into the external iliac nodes
- In addition, lymph from the spongy urethra drains into the inguinal nodes
what are the male accessory glands? which is the largest?
the seminal vesicles, prostate gland (largest), and the bulbourethral glands
what type of gland is the prostate gland?
a branched tubuloalveolar gland
(the prostate is a tubuloalveolar gland composed of multiple secretory acini, each consisting of epithelial cells lining a central lumen)
what is the gland embedded in?
fibromuscular stroma
fibromuscular stroma between the glands accounts for about half of the volume of the prostate
what are the different parts of the prostate? what is anatomically related to each of these parts?
apex, base, anterior, posterior and inferolateral surfaces
- Apex = urethral sphincter
- Base = neck of bladder
- Anterior surface = retropubic space
- Posterior surface = rectum
- Inferolateral surface = levator ani muscle
what does the fibrous capsule of the prostate incorporate?
the prostatic plexuses of nerves and veins
approximately how many prostatic ducts open into the prostatic sinuses?
20-30
where are the prostatic sinuses located?
lateral to the urethral crest
what is the main arterial supply to the prostate?
from branches of the inferior vesical artery
where does lymph from the prostate drain into?
the internal iliac nodes
the prostate gland secretes a milky fluid containing what?
citric acid and acid phosphatase which neutralises the acidity of the vagina
what is the urethral crest?
a median longitudinal elevated ridge
what is the prostatic sinus?
groove on each side of the crest – the prostatic gland opens into the sinuses
what is the prostatic utricle?
a depression on the summit of the urethral crest – the ejaculatory ducts open on the sides of the utricle
