Organs of the Pelvis

Pre-prostatic part of urethra

(intramural) Begins at the internal urethral orifice, located at the neck of the bladder. It passes through the wall of the bladder, & ends at the prostate

Uteric calculus

(kidney stone), is the presence of a solid stone in the urinary tract, formed from minerals within the urine. Can obstruct urinary flow, causing pain & hematuria (blood in the urine)

Bladder Stretch Reflex Arc

-Bladder fills with urine, & bladder walls stretch. -Sensory nerves detect stretch & transmit this info to the spinal cord. -Interneurons within the spinal cord relay the signal to the parasympathetic efferents (the pelvic nerve). -Pelvic nerve acts to contract the detrusor muscle, & stimulate micturition

Nervous supply of bladder

-Sympathetic nervous system communicates w/ bladder via the hypogastric nerve (T12 - L2). It causes relaxation of the detrusor muscle to promote urine retention. -Parasympathetic nervous system communicates w/ the bladder via pelvic nerve (S2-S4). Increased signals from this nerve causes contraction of the detrusor muscle to stimulate micturition. -Somatic nervous supply gives us voluntary control over micturition. It innervates the external urethral sphincter, via the pudendal nerve (S2-S4). It can cause it to constrict (storage phase) or relax (micturition). -Sensory (afferent) nerves that report to the brain. Found in bladder wall & signal need to urinate when bladder becomes full.

3 constrictions in male urethra

1. internal urethral sphincter 2. external urethral sphincter 3. external urethral orifice

Functions of the bladder

1. temporarily store urine 2. assists in expulsion of urine

Internal and External urethral sphincters

2 sphincters controlling the outflow of urine; the internal & external urethral sphincters (C + D)

Ureters

2 thick tubes which transport urine from the kidney to bladder. Are 25cm long, & situated bilaterally, with 1 ureter draining each kidney

3 locations for kidney stone

3 where ureters are at their narrowest -where a stone is more likely to become stuck: 1. Uretopelvic junction 2. Pelvic brim 3. Where the ureter enters the bladder Gold standard investigation for suspected ureteric calculus is CT scan of kidneys, ureters & bladder (CT KUB)

Flacid Bladder- Spinal transection below T12

A spinal cord transection at this level will have damaged the parasympathetic outflow to the bladder. The detrusor muscle will be paralysed, unable to contract. The spinal reflex does not function. In this scenario, bladder will fill uncontrollably, becoming abnormally distended until overflow incontinence occurs

Arterial supply of ureters

Abdominal: Renal artery & testicular/ovarian artery Pelvic: Superior & inferior vesical arteries

Venous drainage of ureters

Abdominal: renal vein & testicular/ovarian vein Pelvic: Superior & inferior vesical veins

Female structures near ureters

As they cross the pelvic brim, ureters are in close proximity to the ovaries. Care must be taken not the damage the ureters during an ovariectomy, especially during the ligation of the ovarian arteries. ~2cm superior to the ischial spine, the ureters run underneath the uterine artery. During a hysterectomy, where the uterus & uterine artery are removed, the ureter is in danger of being accidentally damaged. The relationship b/w the 2 can be remembered using the phrase 'water under the bridge'.

External Urethral sphincter

D

Cystitis

Due to short length of the urethra, women more susceptible to infections of urinary tract. This usually manifests as ______, an infection of the bladder. Common symptoms are dysuria (pain upon urination), frequency, urgency, & hematuria (blood in the urine). A mid stream urine sample can be taken, & tested for the presence of nitrites & leukocytes (both of which indicate infection). Urinary tract infections are treated with a 3 day course of antibiotics

Neck of bladder

Formed by convergence of fundus & the 2 inferolateral surfaces. This structure joins the bladder to the urethra

Male structures near ureters

In men, instead of the uterine arteries, the vas deferens cross the ureters anteriorly

Reflex Bladder- Spinal cord transection above T12

In this case, afferent signals from bladder wall are unable to reach the brain, & pt will have no awareness of bladder filling. There is also no descending control over the external urethral sphincter, & it is constantly relaxed. There is a functioning spinal reflex, where the parasympathetic system initiates detrusor contraction in response to bladder wall stretch. Thus, the bladder automatically empties as it fills - known as the reflex bladder

Fundus of bladder

Located posteriorly. Triangular shaped, with the tip of the triangle pointing backwards

Innervation of ureters

Nervous supply to the ureters is delivered via the renal, testicular/ovarian & hypogastric plexuses. Sensory fibres from the ureters enter the spinal cord at T11-L2, with ureteric pain referred to those dermatomal areas

Pelvic part of ureters

Once within the pelvic cavity, ureters run down the lateral pelvic walls. At level of the ischial spines, they turn anteromedially, moving in a transverse plane towards the bladder. Upon reaching the bladder wall, ureters pierce its lateral aspect in an oblique manner. This creates a 1 way valve, where high intramural pressure collapses the ureters, preventing the back-flow of urine

Spongy Urethra

Passes through the bulb & corpus spongiosum of the penis, ending at the external urethral orifice. In the glans penis, the urethra dilates, forming the navicular fossa. The bulbourethral glands empty into the proximal urethra

Membranous Urethra

Passes through the pelvic floor, & the deep perineal pouch. Is surrounded by the external urethral sphincter, which provides voluntary control of micturition (F)

Prostatic urethra

Passes through the prostate gland. The ejaculatory ducts (containing spermatozoa from the testes, & seminal fluid from the seminal vesicle glands) & the prostatic ducts drain into the urethra here (E)

External urethral orifice

The distal end of the urethra is marked by the presence of 2 mucous glands that lie either side of the urethra. These glands are homologous to the male prostate (Bartholin's glands)

Flow of urine in bladder

Urine enters bladder by the left & right ureters, & exits via the urethra. Internally, these orifices are marked by the trigone - a triangular area located within the fundus. In contrast to the rest of the internal bladder, the trigone has smooth walls.

Venous drainage of bladder

Venous drainage achieved by the vesical venous plexus, which empty into internal iliac vein (aka hypogastric vein)

Vaginal opening

Within the vestibule, the urethral orifice is located anteriorly to the ____________, & 2-3cm posteriorly to the clitoris

Bladder Stretch Reflex

a primitive spinal reflex, in which micturition is stimulated in response to stretch. During toilet training in infants, this spinal reflex is overridden by the higher centers of the brain, to give voluntary control over micturition

ureters

arise in the abdomen as a continuation of the renal pelvis. They terminate in the pelvic cavity, where they drain into the bladder. Divide the anatomical course of the ureters into the abdominal & pelvic components

Pre-pubic angle

can be removed by holding the penis upwards during urinary catheterisation

Internal urethral sphincter

circle

Ureteric walls

comprised of smooth muscle, which contracts to produce peristaltic waves. This propels the urine towards the bladder

Vestibule

female urethra opens directly onto the perineum, in an area b/w the labia minora, known as the _________

Parts of the bladder

has an apex, body, fundus (or base), & neck

Female urethra

is relatively short (~4cm). This predisposes women to urinary tract infections. Urethra begins at the neck of the bladder, & passes inferiorly through the perineal membrane & muscular pelvic floor

Apex of bladder

located superiorly, pointing towards the pubic symphysis. Is connected to the umbilicus by the median umbilical ligament (a remnant of the urachus)

Body of bladder

main part of bladder, located b/w the apex & fundus

Urinary Bladder

organ of the urinary system, situated anteriorly in the pelvic cavity. Is hollow, highly distensible, & rounded in shape. Main function is collection, temporary storage, & expulsion of urine. Has a unique muscular structure, & a complex neurological control Embryologically, derived from the hindgut

Vascular supply of bladder

primarily receives its vasculature from the internal iliac vessels. Arterial supply delivered by the superior vesical branch of the internal iliac artery. In males, is supplemented by the inferior vesical artery, & females by the vaginal arteries. In both sexes, the obturator & inferior gluteal arteries also contribute small branches

Urinary catheterization

process of inserting a tube through the urethra & into the bladder. Used in situations where urine output needs monitoring, or when pt is unable to pass urine *Catheterisation is more complex in males, as there are 2 angles to consider - the infrapubic & prepubic angles

Abdominal Part of ureters

ureters arise from the renal pelvis - a funnel like structure located within hilum of the kidney. Renal pelvis receives urine from the major calyces. The point at which the renal pelvis narrows to form the ureter is known as the ureteropelvic junction. After the ureteropelvic junction, ureters descend down abdomen, along anterior surface of the psoas major. Ureters are a retroperitoneal structure (located behind the peritoneum). At the area of the sacroiliac joints, the ureters cross the pelvic brim, entering the pelvic cavity. At this point, they also cross the bifurcation of the common iliac arteries

Urethra

vessel responsible for transporting urine from the bladder to an external opening in the perineum. Is lined by stratified columnar epithelium, which is protected from the corrosive urine by mucus secreting glands.

Male urethra

~15-20cm long. In addition to urine, the male urethra provides an exit for semen (a fluid containing spermatozoa & sex gland secretions) 4 Parts: 1. pre-prostatic 2. prostatic 3. membranous 4. spongy