Urinary Bladder Female And Male Notes

Urinary Bladder And Urethra Automatic Bladder (neurogenic bladder, reflex bladder)

1. Urinary Bladder And Urethra Definition:

The bladder having no control over the emptying of the urine is called an automatic bladder. The capacity of the bladder is reduced. The walls of the urinary bladder are hypertrophied with some residual urine. It is also called spastic neurogenic bladder.

2. Urinary Bladder And Urethra Causes:

Lesion of the sacral portion of the spinal cord causes automatic bladder. The lesion may be in the

1. Cauda equine
2. Conus medullaris
3. Sacral roots or
4. Pelvic nerve

Read And Learn More: General Histology Questions and Answers

3. Urinary Bladder And Urethra Clinical manifestations:

It is manifested by

1. Loss of normal bladder sensations
2. Reflex activity
3. Inability to initiate urine, and
4. Incontinence.

 

Question – 1: What is the capacity of gallbladder and urinary bladder?

Answer:

1. Gallbladder: 30 to 50 ml

2. Urinary bladder: The capacity of the bladder varies depending upon the age and status of the bladder. The figures are approximate.

1. At birth 2 ounces (60 ml).
2. The capacity when one feels sensations of filling the bladder—4 ounces (120 ml)
3. The capacity when there is a desire to micturate—8 ounces (240 ml)
4. The capacity of the bladder when it becomes painful—16 ounces (480 ml)
5. The maximum capacity of the bladder (anatomical capacity)—32 ounces (960 ml)

Nerve Supply Of Urinary Bladder

Nerve supply: PMT—Parasympathetic nerve MT – Empties

Sympathetic has a filling effect:

1. Parasympathetic Fibres: Parasympathetic fibres is the main motor nerve of the bladder. It reaches via the pelvic splanchnic nerve (nerve originates S2, S3, S4). It empties the bladder. Emptying of the bladder is done by

• Contraction of the detrusor muscle, and
• Relaxation of the internal urethral sphincter.
  

2. Sympathetic Fibres:

Sympathetic fibres are derived from the L1 and L2 segments of the spinal cord. For most of the bladder, the sympathetic fibres are vasomotor and have a filling effect. The filling is done by

• Inhibition to the detrusor, and
• Relaxation of the sphincter vesicae.

3. Somatic Pudendal Nerve: It supplies the external urethral sphincter (sphincter urethrae) which is voluntary.

4. Sensory Nerves: These are carried mainly by parasympathetic nerves and partly by sympathetic nerves.

• Pain sensation is carried by the lateral spinothalamic tract.
• Distension of the bladder is carried by the posterior column.

Question – 2: Describe the urinary bladder under the following heads

1. Gross anatomy
2. Histology
3. Development, and
4. Applied anatomy.

Answer:

Urinary Bladder Introduction: It is a muscular reservoir of urine present in the anterior part

1. Gross Anatomy:

1. Urinary Bladder Location: It is present behind the pubic symphysis, in the anterior part of the pelvic cavity.

• Capacity:  2, 4, 8,16, 32
  • At birth, it is 2 ounces (60 ml).
  • When the capacity of the bladder reaches 4 ounces (120 ml), one gets a sense of filling the bladder.
  • When the bladder is filled beyond 8 ounces (240 ml), one gets the desire to micturate.
  • When the capacity of the bladder reaches 16 ounces (480 ml), it becomes painful.
  • The anatomical capacity of the bladder is 32 ounces (960 ml).

2. Urinary Bladder External features:

1. Shape

• In empty, it is tetrahedral
•  In distended, it is ovoid 

2. Apex

• In empty, it is directed forward.
• In distension, it is directed towards the umbilicus.

3. Base is directed backwards.

4. The neck is the lowest and most fixed part of the bladder.

5. Surfaces

 3. Urinary Bladder  In empty:

• Superior, and
• Inferolateral surfaces.

4. Urinary Bladder In distended bladder:

• Anterior, and
• Posterior.

5. Urinary Bladder Borders: Four

• Left lateral
• Right lateral
• Posterior, and
• Anteroinferior.

6. Urinary Bladder Relations:

•  Male ♂:

• Female ♀:

•  The posterior surface of the bladder:

Relations of the urinary bladder:

7. Urinary Bladder Blood supply:

1. Urinary Bladder Blood supply Arterial supply:

• Major blood supply to the bladder is by
  • Superior vesical artery, a branch of the anterior division of the internal iliac artery.
  • The inferior vesical artery is a branch of the anterior division of the internal iliac artery.

• Minor blood supply to the lower part of the bladder is from
  • The Obturator artery is a branch of the anterior division of the internal iliac artery.
  • The inferior gluteal artery is a branch of the anterior division of the internal iliac artery.
  • The uterine artery is a branch of the anterior division of the internal iliac artery.
  • The vaginal artery is a branch of the anterior division of the internal iliac artery.

2. Venous drainage:

Veins of the bladder do not follow the arteries. They vary in male  ♂ and female ♀

• In males ♂: Veins form a vesicoprostatic plexus. It is present between the bladder and prostate, which drains backwards to the internal iliac vein.
• In female ♀:  Veins form a plexus in the base of the broad ligament. It drains backwards to the internal iliac vein.

8. Urinary Bladder Nerve supply: It is mainly by

1. Parasympathetic fibres:  Parasympathetic fibres provide the main motor innervation of the bladder. It reaches via the pelvic splanchnic nerve (nerve originates S2, S3, S4). The emptying of the bladder is done by parasympathetic fibres.

• Contraction of the detrusor muscle
• Relaxation of the internal urethral sphincter.

2. Sympathetic fibres: Sympathetic fibres are derived from L1 and L2 segments of the spinal cord. For most of the bladder, the sympathetic fibres are vasomotor and have filling action. This is achieved by

• Inhibition to the detrusor, and
• Motor to the sphincter vesicae.

3. Somatic pudendal nerve (S2, S3, S4):  It supplies the external urethral sphincter (sphincter urethrae) which is voluntary.

4. Sensory nerves: These are carried mainly by parasympathetic nerves and partly by sympathetic nerves.

• Pain sensation is carried by the lateral spinothalamic tract.
• Distension of the bladder is carried by the posterior column.

9. Urinary Bladder Lymphatic drainage: The lymphatics of the bladder follow the course of the arteries and drain into internal and external iliac nodes. A few vessels may pass to the internal iliac nodes or to the lateral aortic nodes. Lymphatics drain alongside the vesical blood vessels to the iliac, and then para-aortic nodes.

 

2.  Urinary Bladder Blood supply Histology

The wall of the bladder presents the following coats from the outside inward.

Serous coat: It is lined by simple squamous epithelium. It is present only on the superior surface of the urinary bladder. In other places, it is formed by the adventitial coat.

Muscular coat: It possesses three ill-defined layers of smooth muscle.

1. Outer longitudinal
2. Middle circular, and
3. Inner longitudinal.

Mucosa: It consists of

Transitional epithelium, which consists of

1. Deep layer:  It is formed by columnar cells.
2. Middle layer: It is formed by polyhedral cells.
3. Superficial layer: It is formed by umbrella   shaped cells in an empty bladder. In a distended bladder, the cells are squamous type.

Lamina propria: Muscularis mucosa is absent.

3. Urinary Bladder Blood supply Development:

Chronological: It develops in the 4th to 7th weeks of intrauterine life.

Germ layer:

1. The epithelium of the bladder develops from endoderm and mesoderm.
2. The muscles develop from the mesoderm.

Site: Cloaca.

Urinary Bladder Blood Supply Source:

1. Epithelium of the urinary bladder

1. Except trigone develops from the cranial part of the vesicourethral canal (endoderm).
2. The epithelium of trigone develops from the absorbed part of the mesonephric duct (mesoderm).

2. The muscles and the connective tissue develop from intra-embryonic splanchnopleuric mesoderm.

Urinary Bladder Blood supply Anomalies:

1.  Absence of the urinary bladder.  (A B C D E F)
2. The Bladder may be divided into upper and lower compartments by septum (hourglass bladder
3. There may be Communication with the rectum—vesicorectal fistula.
4.  Diverticulum of the urinary bladder.
5. It is usually at the junction of the trigone and the rest of the bladder.
6. Ectopic vesicae The lower part of the anterior abdominal wall is absent, the bladder is exposed on the surface of the body.
7.  Fistula  Allantois may remain patent entirely and urine passes through the umbilicus.

4. Urinary Bladder Blood supply Applied anatomy:

1. Lesion of the parasympathetic nerve causes

• Loss of control of the micturition
• Retention of urine due to overactivity of the sympathetic nerve.

2. Lesion of the sympathetic nerve fibres causes paralysis of the sphincter vesicae. It results in the dribbling of urine.

3. Lesion of both pyramidal tracts (upper motor neuron lesion) results in loss of voluntary control of micturition.

4. Bilateral anterolateral cordotomy results in the abolition of pain sensation.

5. There is an absence of awareness of bladder filling. There is no sensation of desire to micturate.

6. This is present in an advanced stage of cancer of the bladder.

7. In the posterior column lesion (tabes—wasting dorsal—dorsal column), the bladder is atonic and a large quantity of urine is collected without any reflex contraction.

Female Urethra

1. Female urethra Dimensions:

• 4 cm long.
• 6 mm in diameter

2. Female  ♀  urethra Extent:

• From the internal urethral orifice of the bladder
• To external urethral orifice.

3. Female  ♀  urethra Course:

•  It Begins at the internal urethral orifice. It is approximately opposite of the middle of the pubic symphysis.
• Runs anteroinferiorly behind the symphysis pubis.
• Is embedded in the anterior wall of the vagina.
• Crosses the perineal membrane and ends at the external urethral orifice.
• Ends as an anteroposterior slit.
• Lies anterior to the opening of the vagina, about 2.5 cm behind the glans clitoris.

4. Female  ♀  urethra Interior:

1. Lined by simple mucous-secreting glands.

2. Anterior and posterior walls of the canal possess a ridge. It is called the urethral crest.

3. Features in the urethra

• Pit-like recess
• Mucous urethral glands
• Paraurethral duct.

4. Paraurethral glands lie in the submucous tissue. They open in the lateral wall margin of the external urethral orifice.

5. Female  ♀  urethra Blood supply:

• Arterial supply :
  • Superior vesical artery, a branch of the anterior division of the internal iliac artery.
  • Vaginal artery branch of the anterior division of the internal iliac artery.

• Venous drainage: Vesical plexus around urethra > Vesical venous plexus > internal pudendal vein > internal iliac vein

6. Female  ♀  urethra Lymphatic drainage: External and internal iliac lymph nodes.

7. Female  ♀  urethra Nerve supply

1. Sympathetic: Postganglionic sympathetic fibres arise from the plexus around vaginal arteries.

2. Parasympathetic:

• Preganglionic fibres arise from the S2, S3, and S4 segments of the spinal cord.
• Synapse in the vesical plexus.
• Postganglionic fibres reach the smooth muscles of the urethra.

3. Somatic fibres from S2, S3, and S4 segments of spinal cord.

4. Sensory fibres through a pelvic splanchnic nerve.

8. Female  ♀  urethra Applied anatomy:

The catheterization of the urethra is much easier in females than in males  ♂.

 

Question 3: Describe the male ♂  urethra under the following heads
1. Gross anatomy
2. Histology
3. Development, and
4. Applied anatomy.

Answer:

Male ♂  Urethra Introduction: It is a common tubular passage for the elimination of urine and semen. It extends from the internal urethral orifice to the external urethral orifice at the tip of the penis.

1.   Gross Anatomy:

1. Male ♂  Urethra Dimensions:

• Length: 18 to 20 cm
• Curvatures: There are two curvatures.

2. Male ♂  Urethra Divisions:

1. Prostatic part of the urethra:

Situation: It is present in the prostate gland.

Peculiarity: It is the widest and most dilated part of the male  ♂  urethra.  It is the narrowest at the junction with the membranous urethra.

Internal features: The posterior wall of the prostatic urethra shows the following features.

• The urethral crest is a median longitudinal ridge of mucous membrane.
• The colliculus seminalis is an elevation in the middle of the urethral crest.
• The prostatic utricle is a blind sac about 6 mm long, which lies within the prostate.
  • There is an orifice on the elevation through which the prostatic utricle opens into the urethra.
  • On each side of this orifice, there are openings of the ejaculatory ducts.
  • There are two vertical grooves situated on each side of the urethral crest. They are called prostatic sinuses.
  • Each sinus presents the openings of 20 to 30 prostatic glands.

2. Membranous part of urethra:

Introduction: It passes through the deep perineal space and pierces the perineal membrane.

• It is about 2.5 cm below and behind the pubic symphysis.
• It is the 2nd narrowest and least dilatable part of the male  ♂  urethra.
• It is surrounded by the sphincter urethrae (external urethral sphincter).

The bulbourethral glands are placed one on each side of the membranous urethra and their ducts open into the spongy part of the urethra.

 Internal features: There are many urethral glands. They open into the membranous part of the urethra.

3. Spongy or penile part of the urethra:

Introduction: It is so-called because it lies in the corpus spongiosum of the penis.

Situation: It lies in the corpus spongiosum. It courses through

• Superficial perineal pouch
• Body of penis, and
• Glans penis.

Extent: Begins from the membranous urethra (from the perineal membrane).

Ends: It opens to the exterior by an orifice called the external urethral orifice.

• It is a vertical slit of 6 mm long.
• It is the narrowest part of the urethra.
• It is guarded by two lips called labia.

Dimension:

• Length: 15 cm.
• Diameter: 6 mm in the body of the penis.

Course: It first ascends upwards and forwards in the superficial pouch up to the symphysis pubis. It descends down in the flaccid condition of the penis.

Dilatations:

• Intrabulbar fossa: It lies in the bulb of the penis. It bulges into the floor and on each side. Hence, looks like a trapezium in cross-section.
• Fossa terminalis: It is also called fossa navicularis. It lies within the glans penis.

3. Blood supply:

• Arterial supply:
  • There is no single artery to the urethra. The arteries arise from many sources. They are
  • Inferior vesical, branch of the anterior trunk of the internal iliac artery.
  • Middle rectal, branch of the anterior trunk of the internal iliac artery. It supplies the pelvic part of the urethra.
  • The internal pudendal is a smaller terminal branch of the anterior trunk of the internal iliac artery.
  • The urethral branch is a branch of the artery of the penis (branch of the internal pudendal artery.

•  Venous drainage: It is divided into
  • The anterior urethra is drained by a dorsal vein of the penis > internal pudendal vein > prostatic venous plexus > internal iliac vein.
  • The posterior urethra is drained into the prostatic and vesical venous plexus > internal iliac vein.

4. Nerve supply:   Most of the urethra is supplied by nerves of the autonomous nervous system.

They are terminal parts of somatic nerves.

• Sympathetic fibres: Sympathetic fibres are derived from the superior hypogastric plexus; the pre-ganglionic fibres arise from L1 and L2 segments.
• Parasympathetic fibres: Parasympathetic fibres are derived from pelvic splanchnic nerves, carrying pre-ganglionic fibres from S2, S3 and S4 segments.
• Somatic fibres: Somatic fibres are derived from the urethral branches of the pudendal nerves

5. Lymphatic drainage:

• The lymphatics from prostatic and membranous parts drain into internal and external iliac lymph nodes.
• The lymphatics from the spongy part drain into the deep inguinal and sometimes into external iliac lymph nodes.

 

2. Histology

Muscular coat:

1. The prostatic urethra shows mainly longitudinal muscle.
2. The rest of the urethra demonstrates inner longitudinal and outer circular layers of the smooth muscle

Submucous coat: This consists of erectile vascular tissue.

Mucous membrane: Mucous membrane presents regional variation.

1. Above the colliculus: It is lined by transitional epithelium.
2. Between the colliculus and the terminal fossa: It is lined by stratified columnar epithelium.
3. Distal to terminal fossa: It is lined by stratified squamous non-keratinized epithelium.

 

3. Development

Chronological age: It develops at the end of 3rd month of intrauterine life.

Germ layer:

• Endoderm
• Ectoderm, and
• Mesoderm.

Sources:

• Prostatic part: It is discussed above and below the opening of the ejaculatory duct.
• Above the opening of the ejaculatory duct: The walls are developed from various sources.
• Anterior and lateral wall develops from the caudal part of the vesicourethral canal. It is of endoderm in origin.
• The posterior wall develops from the absorbed part of the mesonephric duct. It is mesoderm in origin.

Below, is the opening of the ejaculatory duct:

The develops from the pelvic part of the definitive urogenital sinus. It develops endoderm in origin.

• The membranous part develops from the pelvic part of the definitive urogenital sinus. It is endodermal in origin.
• The penile part develops from the phallic part of the definitive urogenital sinus, which is endodermal in origin
• The terminal part develops from the ectoderm.

Anomalies:

1. Hypospadias: The urethra opens anywhere on the undersurface of the penis.
2. Epispadias: The urethra opens on the dorsal surface of the penis close to the anterior abdominal wall.
3. Ectopia vesicae: There is deficient infraumbilical part of anterior abdominal wall.

 

4. Applied anatomy

•  Catheterization: A rubber or metallic tube is passed into the bladder through the urethral meatus.
• It is done to drain the urine in retention of the bladder.
• It is important to keep in mind the normal curvatures of the urethra during catheterization.
• The forceful insertion of metallic instruments may create a false passage in the urethra.
•  Rupture of the urethra is common beneath the pubis. It usually falls on a sharp object. This causes extravasation of urine.
  •  Rupture of urethra, superficial to perineal membrane: The results in extravasation of urine in the superficial perineal pouch. The urine accumulates in the scrotum > penis > anterior abdominal wall deep to the fascia of the Scarpa. It may extend up to the umbilicus.
  • Rupture of the urethra, deep to perineal membrane: This produces extravasation of urine in the extraperitoneal space. It accumulates in the anterior abdominal wall superficial to the peritoneum.
•  Urethritis is an inflammation of the urethra.