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Urethra

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Padamjeet Panchal
Padamjeet Panchal

The document summarizes the anatomy of the male and female urethra. It describes the three parts of the male urethra - prostatic, membranous, and spongy/penile urethra. It provides details on the length, location, and features of each part. The document also discusses the arterial supply, venous drainage, and lymphatic drainage of the male urethra. For the female urethra, it notes the length and location, as well as surrounding glands like the urethral and paraurethral glands. Infections of the female urinary bladder are more common due to the shorter length of the female urethra

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Urethra Dr. Padamjeet
Male urethra A. The male urethra is about 20.0 cm long and is divided into three parts- prostatic, membranous and spongy (penile).
The anterior urethra It is about 16 cm long and surrounded by the corpus spongiosum. It is subdivided into: The bulbar urethra which is more proximal, surrounded by the Bulbospongiosus muscles and lie entirely within the perineum. The penile urethra which is distal and continues to the tip of the penis.
The posterior urethra It is about 4 cm long and lies in the pelvis proximal to the corpus spongiosum. The posterior urethra is divided into: The pre-prostatic part of the urethra The prostatic part is the widest and passes through the prostate. The membranous (sphincteric) part is the shortest and narrowest part. In the deep perineal pouch, it is surrounded by distal (external) urethral sphincter.
Parts of male urethra
Preprostatic urethra approximately 1 cm in length extends from the base of the bladder to the prostate. Small periurethral glands at this site may contribute to benign prostatic hyperplasia (BPH) and symptoms of outflow obstruction in older men.
prostatic urethra is 34 cm in length passes through the substance of the prostate, closer to the anterior than the posterior surface of the gland. It is continuous above with the preprostatic part and emerges from the prostate slightly anterior to its apex. - Length: 3.0 cm
prostatic urethra - Features: In its posterior wall there is urethral crest with a round swelling- colliculus seminalis in the middle. There are three openings on the colliculus seminalis: One median for prostatic utricle. Two lateral for the ejaculatory ducts. On either side of urethral crest, there is a shallow depression-prostatic sinus- for prostatic glands ducts opening.
membranous urethra lies in the deep perineal pouch. This is the narrowest segment of male urethra. It is having thickened circular muscles in its walls i.e. sphincter urethrae- that acts as a voluntary external sphincter. more susceptible to injury, during passage of instrument through urethra due to I. Its narrowest part with delicate walls II. Its angulation with the spongy urethra. III. Length: 2.0 cm
spongy (penile) urethra The longest part of male urethra. Length-I5 cm. It begins below the perineal membrane and ends at external urethral meatus. This part lies within the bulb of penis, corpus spongiosum and glans of penis. There are two dilatations in this part: i. One intrabulbar fossa in the bulb of penis. ii. One navicular fossa in the glans of penis.
spongy (penile) urethra The ducts of bulbo-urethral (Cowper's) gland open in this part just below urogenital diaphragm. The dorsal wall of spongy urethra has - Openings of many mucus glands. - Lacunae or pit-like recesses directed forwards. The lacuna magna lies in the navicular fossa. The spongy urethra ends at external urethral meatus, that is a sagittal slit, about 6 mm long at the tip of the glans. The external meatus is guarded by two lateral labia. It is the narrowest point of male urethra. If an instrument can pass through it, it can easily pass through rest of urethra.
ARTERIAL SUPPLY Urethral artery just below the perineal membrane it arises from the internal pudendal artery or common penile artery runs through the corpus spongiosum, to reach the glans penis. It supplies the urethra and erectile tissue around it. In addition, the urethra is supplied by the dorsal penile artery via its circumflex branches on each side and retrogradely from the glans, by its terminal branches. The blood supply through the corpus spongiosum is so plentiful that the urethra can be divided without compromising its vascular supply.
Venous drainage The anterior urethra drains into to the dorsal veins of the penis and internal pudendal veins which drain to the prostatic plexus. The posterior urethra drains into the prostatic venous plexus vesical venous plexus, which drain into the internal iliac veins.
LYMPHATIC DRAINAGE Vessels from the posterior urethra pass mainly to the internal iliac nodes. a few may end in the external iliac nodes. Vessels from the anterior urethra accompany those of the glans penis, ending in the deep inguinal nodes. Some may end in superficial nodes, others may traverse the inguinal canal to end in the external iliac nodes. Vessels from the membranous urethra accompany the internal pudendal artery.
female urethra it is about 4.0 cm long and 6mm diameter. It extends from the neck of bladder to the external urethral meatus. the external orifice is situated in front of the vaginal opening and about 2.5 cm behind the glans clitoridis It is homologous with upper part of prostatic urethra of males. Location: The female urethra is embedded in anterior wall of vagina. Thus in cases of difficult child-birth, it is more likely to be lacerated.
Lumen of Urethra on cross section At the internal orifice- crescentic with the convexity directed in front. At the middle- transverse slit. At the external orifice- sagittal slit.
Glands around the female urethra Urethral glands- These are tubular mucous glands surround the entire urethra. Para-urethral glands- These correspond with the prostate gland of male their ducts open close to the external urethral orifice. Greater vestibular glands- compound racemose glands situated behind the bulb of the vestibule in the superficial perineal pouch ducts of the glands open in the vagina below the hymen. Corresponds to the bulbourethral glands of male Urethral lacunae- These are pit like mucous recesses which project from the entire female urethra.
applied infection of the female urinary bladder is more common due to the shortness of the urethra. stress incontinence is associated with the funneling of the bladder neck during normal standing usually observed in multiparous women with symtoms of sudden dribbling of urine during increases intra-abdominal pressure.

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Urethra

  • 2. Male urethra A. The male urethra is about 20.0 cm long and is divided into three parts- prostatic, membranous and spongy (penile).
  • 3. The anterior urethra It is about 16 cm long and surrounded by the corpus spongiosum. It is subdivided into: The bulbar urethra which is more proximal, surrounded by the Bulbospongiosus muscles and lie entirely within the perineum. The penile urethra which is distal and continues to the tip of the penis.
  • 4. The posterior urethra It is about 4 cm long and lies in the pelvis proximal to the corpus spongiosum. The posterior urethra is divided into: The pre-prostatic part of the urethra The prostatic part is the widest and passes through the prostate. The membranous (sphincteric) part is the shortest and narrowest part. In the deep perineal pouch, it is surrounded by distal (external) urethral sphincter.
  • 5. Parts of male urethra
  • 6. Preprostatic urethra approximately 1 cm in length extends from the base of the bladder to the prostate. Small periurethral glands at this site may contribute to benign prostatic hyperplasia (BPH) and symptoms of outflow obstruction in older men.
  • 7. prostatic urethra is 34 cm in length passes through the substance of the prostate, closer to the anterior than the posterior surface of the gland. It is continuous above with the preprostatic part and emerges from the prostate slightly anterior to its apex. - Length: 3.0 cm
  • 8. prostatic urethra - Features: In its posterior wall there is urethral crest with a round swelling- colliculus seminalis in the middle. There are three openings on the colliculus seminalis: One median for prostatic utricle. Two lateral for the ejaculatory ducts. On either side of urethral crest, there is a shallow depression-prostatic sinus- for prostatic glands ducts opening.
  • 9. membranous urethra lies in the deep perineal pouch. This is the narrowest segment of male urethra. It is having thickened circular muscles in its walls i.e. sphincter urethrae- that acts as a voluntary external sphincter. more susceptible to injury, during passage of instrument through urethra due to I. Its narrowest part with delicate walls II. Its angulation with the spongy urethra. III. Length: 2.0 cm
  • 10. spongy (penile) urethra The longest part of male urethra. Length-I5 cm. It begins below the perineal membrane and ends at external urethral meatus. This part lies within the bulb of penis, corpus spongiosum and glans of penis. There are two dilatations in this part: i. One intrabulbar fossa in the bulb of penis. ii. One navicular fossa in the glans of penis.
  • 11. spongy (penile) urethra The ducts of bulbo-urethral (Cowper's) gland open in this part just below urogenital diaphragm. The dorsal wall of spongy urethra has - Openings of many mucus glands. - Lacunae or pit-like recesses directed forwards. The lacuna magna lies in the navicular fossa. The spongy urethra ends at external urethral meatus, that is a sagittal slit, about 6 mm long at the tip of the glans. The external meatus is guarded by two lateral labia. It is the narrowest point of male urethra. If an instrument can pass through it, it can easily pass through rest of urethra.
  • 12. ARTERIAL SUPPLY Urethral artery just below the perineal membrane it arises from the internal pudendal artery or common penile artery runs through the corpus spongiosum, to reach the glans penis. It supplies the urethra and erectile tissue around it. In addition, the urethra is supplied by the dorsal penile artery via its circumflex branches on each side and retrogradely from the glans, by its terminal branches. The blood supply through the corpus spongiosum is so plentiful that the urethra can be divided without compromising its vascular supply.
  • 13. Venous drainage The anterior urethra drains into to the dorsal veins of the penis and internal pudendal veins which drain to the prostatic plexus. The posterior urethra drains into the prostatic venous plexus vesical venous plexus, which drain into the internal iliac veins.
  • 14. LYMPHATIC DRAINAGE Vessels from the posterior urethra pass mainly to the internal iliac nodes. a few may end in the external iliac nodes. Vessels from the anterior urethra accompany those of the glans penis, ending in the deep inguinal nodes. Some may end in superficial nodes, others may traverse the inguinal canal to end in the external iliac nodes. Vessels from the membranous urethra accompany the internal pudendal artery.
  • 15. female urethra it is about 4.0 cm long and 6mm diameter. It extends from the neck of bladder to the external urethral meatus. the external orifice is situated in front of the vaginal opening and about 2.5 cm behind the glans clitoridis It is homologous with upper part of prostatic urethra of males. Location: The female urethra is embedded in anterior wall of vagina. Thus in cases of difficult child-birth, it is more likely to be lacerated.
  • 16. Lumen of Urethra on cross section At the internal orifice- crescentic with the convexity directed in front. At the middle- transverse slit. At the external orifice- sagittal slit.
  • 17. Glands around the female urethra Urethral glands- These are tubular mucous glands surround the entire urethra. Para-urethral glands- These correspond with the prostate gland of male their ducts open close to the external urethral orifice. Greater vestibular glands- compound racemose glands situated behind the bulb of the vestibule in the superficial perineal pouch ducts of the glands open in the vagina below the hymen. Corresponds to the bulbourethral glands of male Urethral lacunae- These are pit like mucous recesses which project from the entire female urethra.
  • 18. applied infection of the female urinary bladder is more common due to the shortness of the urethra. stress incontinence is associated with the funneling of the bladder neck during normal standing usually observed in multiparous women with symtoms of sudden dribbling of urine during increases intra-abdominal pressure.
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