Podcast
Questions and Answers
What type of muscle is the internal sphincter primarily composed of?
What type of muscle is the internal sphincter primarily composed of?
The female urethra is approximately 10-15 cm long.
The female urethra is approximately 10-15 cm long.
False
What nerve supplies the external sphincter of the bladder?
What nerve supplies the external sphincter of the bladder?
Pudendal nerve
Increased abdominal pressure can result in __________ urinary incontinence.
Increased abdominal pressure can result in __________ urinary incontinence.
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Match the following terms with their descriptions.
Match the following terms with their descriptions.
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Which structure supports the female urethra?
Which structure supports the female urethra?
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The normal adult bladder has a capacity of about 100 mL.
The normal adult bladder has a capacity of about 100 mL.
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What clinical condition is commonly caused by urethral obstruction due to enlarged prostate in males?
What clinical condition is commonly caused by urethral obstruction due to enlarged prostate in males?
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The urethra in females opens into the __________, located between the clitoris and the vagina.
The urethra in females opens into the __________, located between the clitoris and the vagina.
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Where are urinary stones most likely to become lodged within the ureter?
Where are urinary stones most likely to become lodged within the ureter?
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What is the primary function of the urinary bladder?
What is the primary function of the urinary bladder?
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The maximum capacity of the bladder in healthy adults is about 200-300ml.
The maximum capacity of the bladder in healthy adults is about 200-300ml.
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Name the triangular area at the base of the bladder where the ureters enter and the urethra exits.
Name the triangular area at the base of the bladder where the ureters enter and the urethra exits.
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The bladder has a strong muscular wall known as the ______ muscle.
The bladder has a strong muscular wall known as the ______ muscle.
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Match the following terms related to the urinary bladder with their descriptions:
Match the following terms related to the urinary bladder with their descriptions:
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Which arteries supply blood to the bladder?
Which arteries supply blood to the bladder?
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The bladder is located behind the pubic bones within the abdomen.
The bladder is located behind the pubic bones within the abdomen.
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What is the name of the condition of the bladder when it is filled and becomes ovoid?
What is the name of the condition of the bladder when it is filled and becomes ovoid?
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The circular component of the bladder's muscular coat is thickened to form the ______.
The circular component of the bladder's muscular coat is thickened to form the ______.
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Which type of nerves stimulate contraction of the detrusor muscle?
Which type of nerves stimulate contraction of the detrusor muscle?
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What is a common anatomic cause of urinary retention in females?
What is a common anatomic cause of urinary retention in females?
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The male urethra is solely responsible for transporting urine.
The male urethra is solely responsible for transporting urine.
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What is the primary muscle involved in bladder contraction?
What is the primary muscle involved in bladder contraction?
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The male urethra can be divided into three parts: prostatic, ________, and spongy.
The male urethra can be divided into three parts: prostatic, ________, and spongy.
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Match the following components of the male urethra with their characteristics:
Match the following components of the male urethra with their characteristics:
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What can cause the bladder to rupture intraperitoneally?
What can cause the bladder to rupture intraperitoneally?
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The bladder's histological details are different from those of the ureter.
The bladder's histological details are different from those of the ureter.
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What type of epithelium lines the urethra?
What type of epithelium lines the urethra?
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The ________ urethra is the narrowest and least dilatable portion of the male urethra.
The ________ urethra is the narrowest and least dilatable portion of the male urethra.
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What does the cystoscope allow for observation of?
What does the cystoscope allow for observation of?
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Which artery supplies the prostatic urethra?
Which artery supplies the prostatic urethra?
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The penile urethra has a more complex catheterization process compared to the female urethra.
The penile urethra has a more complex catheterization process compared to the female urethra.
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What is the function of Skene’s glands in females?
What is the function of Skene’s glands in females?
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The urethral opening in females is located within the vestibule, ___ to the vaginal opening.
The urethral opening in females is located within the vestibule, ___ to the vaginal opening.
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Match the portion of the urethra with its respective lymphatic drainage:
Match the portion of the urethra with its respective lymphatic drainage:
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What is the primary purpose of urinary catheterization in males?
What is the primary purpose of urinary catheterization in males?
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The distal end of the female urethra is marked by the presence of Skene's glands.
The distal end of the female urethra is marked by the presence of Skene's glands.
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What anatomical feature in males can make catheterization more difficult?
What anatomical feature in males can make catheterization more difficult?
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Penile urethra ends at the external urethral ___ .
Penile urethra ends at the external urethral ___ .
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Which portion of the male urethra is supplied by the bulbourethral artery?
Which portion of the male urethra is supplied by the bulbourethral artery?
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Study Notes
Anatomy of the Urinary Bladder
- The bladder is a hollow organ in the urinary system, with distensible walls.
- It stores urine, accommodating 400-600 mL in healthy adults.
- The bladder's internal lining, rugae, allows expansion.
- The bladder contracts during micturition (urination), aided by sphincter relaxation.
Urinary Bladder - Location and Description
- Located immediately behind the public bones, within the pelvis.
- Holds approximately 400-600 mL of urine in adults.
- Possesses a strong muscular wall.
Bladder - Additional Features
- The empty bladder is pyramidal, having an apex, base, and two inferolateral surfaces, plus a neck.
- The trigone is a triangular area at the bladder base where ureters enter and the urethra exits.
- The bladder's apex lies behind the pubic symphysis and connects to the umbilicus (via the median umbilical ligament).
- As the bladder fills, its superior surface bulges upward into the abdominal cavity, and the peritoneal covering peels back, enabling direct contact with the anterior abdominal wall.
Bladder - Internal Structure
- The bladder's muscular coat consists of smooth muscle; three interlacing layers collectively known as detrusor muscle.
- At the neck of the bladder, the circular component of the detrusor muscle forms the sphincter vesicae.
- The uvula vesicae is a small elevation behind the urethral orifice, formed by the median lobe of the prostate.
Bladder - Blood Supply
- The bladder is supplied by the superior and inferior vesical arteries (branches of the internal iliac arteries).
- Veins form the vesical venous plexus, draining into the internal iliac vein.
- Lymph drainage occurs through internal and external iliac nodes.
Bladder - Nerve Supply
- Sympathetic nerves inhibit detrusor muscle contraction and stimulate sphincter vesicae closure.
- Parasympathetic nerves stimulate detrusor muscle contraction and inhibit sphincter vesicae action.
Control of Micturition
- The internal sphincter is smooth muscle at the bladder neck.
- It is supplied by sympathetic nerves and contracts the detrusor muscle.
- Internal sphincter relaxes when parasympathetic nerves activate.
- The external sphincter is striated muscle, supplied by the perineal branch of the pudendal nerve (S2,3,4).
Structure of Female Urethra
- Approximately 3-5 cm in length.
- Enters a deep pouch, surrounded by the external urethral sphincter.
- Pierces the perineal membrane.
- Does not have fascia between the lower two-thirds of the urethra and vagina.
- Opens into the vestibule between clitoris and vagina.
Urethra - Structure
- The urethral muscular layer is continuous with the bladder.
- Contains spongy erectile tissue and a plexus of veins.
- The lining is transitional epithelium initially, becoming non-keratinized stratified squamous distally.
- Contains paraurethral glands analogous to prostatic glands.
Urethra - Support and Function
- Supported by pelvic floor fascia, pubovesical, and pubocervical ligaments.
- Insufficient support can lead to downward displacement during increased abdominal pressure (stress urinary incontinence).
- Pregnancy, delivery and menopause can increase susceptibility to stress urinary incontinence.
Urethra - Clinical Correlates
- Ureteric calculi (kidney stones) may become lodged where the ureter narrows in the pelvis and passes through the bladder wall.
- A full bladder in the adult can be palpated above the pubic symphysis through the anterior abdominal wall.
Bladder distention
- Normal adult bladder capacity is 500 mL.
- Significant bladder distension can occur with urinary obstruction; up to 1000-1200 mL can be drained via catheter in such cases.
- Adult male urinary retention commonly arises from prostate enlargement, acute urethritis or prostatitis.
- In females, acute urinary retention is less common, except for conditions like urethral inflammation (e.g., herpes).
- As the bladder fills, the superior wall rises out of the pelvis, lifting the peritoneum off the anterior abdominal wall.
Cystoscopy
- An illuminated tube fitted with lenses is inserted through the urethra into the bladder. This enables examination of the bladder's mucous membrane and urethral/ureteric orifices.
- Distension of the bladder with fluid facilitates observation.
Bladder Injuries
- Ruptures can be intraperitoneal or extraperitoneal, predominantly impacting the superior bladder wall when full and extended into the abdomen.
Histology of Urinary Bladder
- Histological details of the urinary bladder are comparable to the ureter, excluding the lamina muscularis.
- Small, isolated bundles of smooth muscles constitute the lamina muscularis.
- The tunica muscularis is thick, grouped muscles collectively named detrusor muscle.
Anatomy of the Male Urethra
- Approximately 15-20 cm long.
- Transports urine and semen (spermatozoa plus secretions from the sex glands).
- Comprises prostatic, membranous, and penile (bulbous) portions.
- Prostatic urethra begins at the bladder neck, traversing the prostate gland.
- Receives ejaculatory and prostatic ducts.
- Bulbous urethra passes through the bulb and corpus spongiosum of the penis, terminating at the urethral meatus.
- Membranous urethra is located within the pelvic floor and deep perineal pouch, contains external urethral sphincter, narrowest and least dilatable.
- The ejaculatory ducts add semen and prostatic secretions.
- The urethra's penile segment dilates within the penile glans to form the navicular fossa.
Male Urethra - Neurovascular Supply
- Arterial supply from inferior vesical (prostatic urethra), branches of internal pudendal (membranous and penile urethra).
- Nerve supply arises from the prostatic plexus (sympathetic, parasympathetic and visceral afferent fibres).
Male Urethra - Lymphatic Drainage
- Prostatic and membranous portions drain to obturator and internal iliac nodes.
- Penile portion drains to deep and superficial inguinal nodes.
Male Catheterization
- Process of inserting a catheter through the urethra into the bladder.
- Important clinically when monitoring urinary output or when patients can't void (urinary retention).
- More complex in males due to infrapubic and prepubic angles, requiring special considerations in positioning.
Anatomy of Female Urethra
- Relatively short (approximately 4 cm).
- Begins at the bladder neck and descends through perineal membrane and pelvic floor muscles, exiting into the vestibule.
- Urethral opening anterior to vaginal opening and slightly posterior to clitoris.
- Two mucus-producing Skene's glands located on each side of the urethra, homologous to the male prostate.
Female Urethra - Neurovascular Supply
- Arterial supply via internal pudendal, vaginal arteries, and inferior vesical branches of vaginal arteries.
- Venous drainage by similar-named veins.
- Nerve supply from vesical plexus and pudendal nerve.
- Visceral afferents travel through pelvic splanchnic nerves.
Female Urethra - Lymphatic Drainage
- Proximal urethra drains to internal iliac nodes.
- Distal urethra drains to superficial inguinal lymph nodes.
Clinical Relevance - Urinary Tract Infections
- Women more susceptible due to shorter urethra.
- Infections typically involve bladder (cystitis).
- Common symptoms include dysuria, frequency, urgency, and haematuria.
- Urine samples can be tested for nitrites and leukocytes to confirm infections.
- Simple infections are often treated with a 3-day course of antibiotics.
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Description
Explore the structure and function of the urinary bladder in this quiz. Learn about its location, capacity, and unique features such as the trigone and rugae. Perfect for anatomy students seeking to understand this vital organ.
