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RENAL AND UROLOGY

2005 The Medicine Publishing Company Ltd97SURGERY 23:3

This contribution should be read with Role of the bladder in

storage and micturition, page 93, and Urinary incontinence in

adults, page 101.

Urinary bladder (Figure 1)

The empty bladder is extraperitoneal and roughly pyramidal.

Superiorly it is covered by the pelvic peritoneum, with coils of

small intestine and the sigmoid loop lying against it. In the female,the anteverted body of the uterus lies against its posterosuperior

aspect.

Anteriorly, the bladder lies behind the pubis, with its apex

attached by a fibrous strand, the median umbilical ligament, to

the umbilicus. This represents the remains of the fetal urachus.

Posteriorly in the male, the base of the bladder relates to the

rectum, the vasa deferentia and the seminal vesicles; in the female,

to the vagina and the supravaginal cervix. It receives the ureters at

its upper lateral angles. Laterally, the inferolateral surfaces relate

to the levator ani and obturator internus muscles on each side.

The bladder neck fuses with the male prostate; in the female

it rests directly on the pelvic fascia.

As the bladder distends, in retention of urine it becomes spheri-cal and projects into the lower abdomen, stripping the peritoneum

upwards from the anterior abdominal wall. This allows safe extra-

peritoneal puncture of the distended bladder to be performed.

In the infant, because the pelvis is comparatively small, the

bladder neck is level with the upper part of the symphysis and the

bladder itself, although still extraperitoneal, is in contact with the

anterior abdominal wall.

The interior of the bladder is readily visualized through the

cystoscope (Figure 2). The ureteric orifices are seen as a slit on

either side. Between them, a raised fold of mucosa, the inter-

ureteric ridge, is constantly visible, produced by an underlying bar

of muscle. Between the ureteric orifices and the urethral orifice is

the smooth triangular area of the trigone. The involuntary muscle of the bladder wall is formed by a

criss-cross of fibres. When these undergo hypertrophy as a result

of chronic urethral obstruction, they produce the characteristic

trabeculated appearance at cystoscopy.

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2

Posterosuperior aspect of the male internal

urogenital organs

Urachus

Ureter

Prostate

Membranous part of urethra

Seminal

vesicle

Deferent

duct

Anterior aspect of the interior of the urinary bladder

Probe in

right ureter

Interureteric

crest

Orifice of

left ureter

Trigone

Uvula

Internal

urethral

orifice

Anatomy of the urinarybladder, prostate and maleurethra

Harold Ellis

Harold Ellisis Emeritus Professor of Surgery, University of London

(Charing Cross and Westminster Medical School), London, UK. He is

Clinical Anatomist in the Division of Anatomy at Kings College, London,

at the Guys Campus, London, UK.

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RENAL AND UROLOGY

2005 The Medicine Publishing Company Ltd98SURGERY 23:3

Blood supply is from the superior and inferior vesical branches

of the internal iliac artery. The vesical veins form a plexus which

drains into the internal iliac vein.

Lymphatics drain along the vesical blood vessels to the iliac

and then the para-aortic nodes.

Prostate

The prostate gland is a pyramidal fibromuscular and glandular

organ, the size and shape of a chestnut, that surrounds the com-

mencement of the urethra.

Above, it continues with the neck of the bladder, the urethra

entering near its anterior border. Below, the apex of the gland rests

on the sphincter urethrae, which lies within the deep perineal

pouch.

Behind lies the rectum, separated by the loose fascia of Denon-

villiers, while in front lies the pubic symphysis separated from it

by extraperitoneal fat in the retropubic space (cave of Retzius).

Close against the prostate in this space lies the prostatic plexus

of veins. Near its apex, a condensation of connective tissue, the

puboprostatic ligament, passes forward to the pubis. Laterally lies the levator ani. On either side the ejaculatory

duct, formed by fusion of the vas and the seminal vesicle, enters

the upper posterior part of the prostate to open into the urethra

at the colliculus seminalis (see below), thus dividing off a median

prostatic lobe between them.

The arterial supply of the gland is from the inferior vesical

artery, a branch entering the prostate on each side at its lateral

extremity.

The prostatic plexus of veins receives the dorsal vein of the

penis and drains into the internal iliac vein on each side. Some of

the venous drainage connects with valveless vertebral veins (the

valveless vertebral veins of Bateson), which explains the spread

of prostatic cancer to the pelvis and vertebrae.

Male urethra (Figure 3)

The male urethra is 1820 cm in length and is divided into the

prostatic, membranous and spongy parts.

The prostatic urethra

The prostatic urethra is 34 cm in length and traverses the pros-

tate. Its posterior wall bears a longitudinal elevation along its

length termed the urethral crest. On each side of this is the shal-

low groove of the prostatic sinus, into which the 1520 prostatic

ducts empty the secretion of the gland. At about the middle of the

crest is a prominence, the colliculus seminalis (or verumontanum)into which opens the prostatic utricle, or utriculus masculinus, a

blind tract about 5 mm in length. This is believed to be the male

remnant of the paramesonephric duct, which develops into the

female genital tract. On either side of the utricle open the ejacula-

tory ducts.

The membranous urethra

The membranous urethra is 2 cm in length, the shortest, least

dilatable and, apart from the external orifice, the narrowest part

of the urethra. It traverses the external urethral sphincter within

the deep perineal pouch.

The spongy urethra

The spongy urethra is 15 cm in length and traverses the corpus

spongiosum of the penis. First, it passes upwards and forwards to

lie below the pubic symphysis (the bulb of the urethra); then, in

the flaccid state, it bends downwards and forwards. The external

orifice, a vertical slit, is the narrowest part of the urethra. Immedi-ately within the meatus, the urethra dilates into a terminal fossa,

the roof of which bears a mucosal fold, the lacuna magna, which

may catch the tip of a catheter.

Openings of prostatic utricle and ejaculatory ducts on the

colliculus seminalis.

The whole length of the lumen of the male urethra

exposed by an incision extending into it from its

dorsal aspect

Bladder

Prostate

Crus

Corpus cavernosum

penis

Corpus spongiosumpenis

Spongy part of urethra

Large lacuna in

navicular fossa

External urethral orifice

Bulb

Urethral crestColliculus seminalis

Prostatic part of urethra

Membranous part

of urethra

Small lacuna

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