Pelvic viscera in the male pdf - Pelvis

Basic Anatomy

269

prolapse
of mucous
membrane

anus

external anal
sphincter

internal anal
sphincter

levator ani

peritoneum

mucous membrane

rectum

peritoneum

complete
prolapse
of rectal wall

internal anal
sphincter

external anal
sphincter

rectum

FIGURE 7.7

Coronal section of the rectum and anal canal.

is described on page 209.

to the posterior surface of the bladder. Its abdominal course

Each ureter is a muscular tube that extends from the kidney

vic cavity in the male are described in the following sections.

described above. The contents of the anterior part of the pel

occupy the posterior part of the pelvic cavity in both sexes, as

The rectum, sigmoid colon, and terminal coils of ileum

Pelvic Viscera in the Male

Complete rectal prolapse.

Incomplete rectal (mucosal) prolapse.

Ureters

to form the

treatment is operative excision of the aganglionic segment of

ment of the parasympathetic ganglion cells in this region. The

histologic examination reveals a complete failure of develop

stricted segment of the bowel that causes the obstruction, and

rectum and anal canal are constricted (Fig. 7.10). It is the con

sigmoid colon is greatly distended and hypertrophied, while the

nium, and the abdomen becomes enormously distended. The

during the first few days after birth. The child fails to pass meco

common in males than in females. Symptoms usually appear

Hirschsprung disease shows a familial tendency and is more

It starts to accumulate at

green in color and is called

gland secretions, bile, and amniotic fluid. This substance is dark

The lining of the inferior half of the anal canal is

anal canal.

Fig. 7.8). The fates of the primitive bladder and the urogenital

(see

On reaching the cloacal membrane, the urorectal

urogenital

the anterior part of

and divides the cloaca into anterior and posterior parts. The

of the mesenchyme, a septum is formed that grows inferiorly

chyme invaginates the entoderm. With continued proliferation

(see Fig. 7.8). In the interval

entodermal cloaca

between the allantois and the hindgut, a wedge of mesen-

septum is called the urorectal septum,

the cloaca becomes the primitive bladder and the
sinus, and the posterior part of the cloaca forms the anorec-
tal canal.

septum fuses with it and forms the future perineal body

sinus in both sexes are considered in detail on page 280.

The anorectal canal forms the rectum and the superior half of

the

formed from the ectoderm of the proctodeum (Fig. 7.9). The pos-

terior part of the cloacal membrane breaks down so that the gut

opens onto the surface of the embryo.

Hindgut Artery
The hindgut, which extends from the left colic flexure to half-

way down the anal canal, is supplied by the inferior mesenteric

artery (see Fig. 5.46). Here, a number of ventral branches of the

aorta fuse to form a single artery.

Meconium
At full term, the large intestine is filled with a mixture of intestinal

meconium.

4 months and reaches the rectum at the fifth month.

Primary Megacolon (Hirschsprung Disease)

the bowel.

270

CHAPTER 7

The Pelvis: Part II—The Pelvic Cavity

allantois

genital tubercle

proctodeum

cloacal membrane

hindgut

entodermal cloaca

direction of growth

of mesenchymal wedge

urorectal septum

proctodeum

primitive

bladder

urogenital sinus

perineal body

cloacal membrane

urorectal septum

anorectal canal

FIGURE 7.8

Progressive stages (

(the primitive bladder and the urogenital sinus) and a posterior part (the anorectal canal).

) in the formation of the urorectal septum, which divides the cloaca into an anterior part

1–4

columnar epithelium hindgut entoderm

rectum

anal canal

stratified squamous epithelium

proctodeum ectoderm

sensitive to distention

(autonomic nerves)

levator ani muscle

blood supply from

superior rectal vessels

(inferior mesenteric)

blood supply from

inferior rectal vessels

(internal iliac)

sensitive to all general sensations

(spinal nerves)

dentate line site of anal valves

embryologic site of cloacal membrane

FIGURE 7.9

Structure of the anal canal and its embryologic origin.

Basic Anatomy

271

distended and hypertrophied

sigmoid colon

constricted rectum

and anal canal

commonest area to find absence

of parasympathetic

ganglion cells

FIGURE 7.10

Main characteristics of primary megacolon (Hirschsprung disease).

tact with the anterior abdominal wall.

abdominal wall so that the bladder comes into direct con

toneal covering is peeled off the lower part of the anterior

surface bulges upward into the abdominal cavity. The peri

As the bladder fills, it becomes ovoid, and the superior

peritoneum passes to the lateral pelvic walls.

(see Fig. 7.4). Along the lateral margins of this surface, the

itoneum and is related to coils of ileum or sigmoid colon

of the bladder is covered with per

superior surface

The

vesicles, and the rectovesical fascia (see Fig. 7.4).

rated from the rectum by the vasa deferentia, the seminal

cal pouch. The lower part of the posterior surface is sepa

peritoneum, which forms the anterior wall of the rectovesi

part of the posterior surface of the bladder is covered by

seminal vesicles from each other (see Fig. 7.13). The upper

side on the posterior surface of the bladder and separate the

urethra (see Fig. 7.13). The two vasa deferentia lie side by

joined by the ureters, and the inferior angle gives rise to the

posteriorly and is triangular. The superolateral angles are

of the bladder, faces

posterior surface

The

(remains of urachus).

umbilical ligament

median

and 7.12). It is connected to the umbilicus by the

the upper margin of the symphysis pubis (see Figs. 7.4

of the bladder points anteriorly and lies behind

apex

The

it also has a neck.

apex, a base, and a superior and two inferolateral surfaces;

The empty bladder is pyramidal (Fig. 7.13), having an

to take up the adult position.

the pelvic cavity enlarges, the bladder sinks into the pelvis

empty bladder projects above the pelvic inlet; later, when

the hypogastric region (Fig. 7.12). In the young child, the

the pelvis; as the bladder fills, its superior wall rises up into

tains. The empty bladder in the adult lies entirely within

tions vary according to the amount of urine that it con

The bladder has a strong muscular wall. Its shape and rela

and in the adult has a maximum capacity of about 500 mL.

pubic bones (see Fig. 7.4) within the pelvis. It stores urine

The urinary bladder is situated immediately behind the

Location and Description

the ureter are described on page 211.

The blood supply, lymph drainage, and nerve supply of

pierces the bladder wall.

as it crosses the pelvic brim to enter the pelvis, and where it

pelvis joins the ureter in the abdomen, where it is kinked

The ureter possesses three constrictions: where the renal

Constrictions

into the bladder.

of the bladder for about 0.75 in. (1.9 cm) before opening

vas deferens. The ureter passes obliquely through the wall

bladder (Fig. 7.11). Near its termination, it is crossed by the

spine and turns forward to enter the lateral angle of the

front of the internal iliac artery to the region of the ischial

Each ureter then runs down the lateral wall of the pelvis in

of the common iliac artery in front of the sacroiliac joint.

The ureter enters the pelvis by crossing the bifurcation

Urinary Bladder

-
-

base,

-
-

psoas

ilium

sacrum

ischial spine

obturator
internus

prostate

bladder

vas deferens

inferior epigastric artery

external iliac artery

internal iliac artery

common iliac
vessels

ureter

FIGURE 7.11

Right half of the pelvis showing relations of

the ureter and vas deferens.

272

CHAPTER 7

The Pelvis: Part II—The Pelvic Cavity

peritoneum

body of
pubis

ureter

urethra

apex of bladder

interureteric crest

left ureter

left ureteric
orifice

trigone

urethral orifice

uvula vesicae

right ureter

cut bladder
wall

superior wall
of bladder

FIGURE 7.12

bladder is peeled off from the anterior abdominal wall as the

that the peritoneum covering the superior surface of the

superior wall rises as the viscus fills with urine. Note also

Lateral view of the bladder. Note that the

bladder fills. B. Interior of the bladder in the male as seen

from in front.

superior surface

of bladder

left ureter

prostate

membranous

part of urethra

neck of bladder

apex of bladder

left ureter

superior

surface of bladder

right ureter

right

vas deferens

ampulla of

vas deferens

right

seminal vesicle

posterior surface of

prostate

membranous part of

urethra

left

seminal vesicle

left

vas deferens

left

seminal vesicle

left

vas deferens

FIGURE 7.13

is composed of

muscular coat of the bladder

The

lobe of the prostate.

thral orifice, which is produced by the underlying median

is a small elevation situated immediately behind the ure

uvula vesicae

The

interureteric ridge.

and is known as the

runs from the opening of one ureter to that of the other

The trigone is limited above by a muscular ridge, which

as the bladder fills.

which prevents a reverse flow of urine toward the kidneys

bladder wall obliquely, and this provides a valvelike action,

nal urethral orifice (see Fig. 7.12). The ureters pierce the

openings of the ureters, and the inferior angle to the inter

The superior angles of the trigone correspond to the

brane is firmly adherent to the underlying muscular coat.

viscus is empty (see Fig. 7.12), because the mucous mem

the mucous membrane is always smooth, even when the

Here,

trigone.

surface of the base of the bladder is called the

is full. The area of mucous membrane covering the internal

bladder is thrown into folds that disappear when the bladder

of the greater part of the empty

mucous membrane

The

vious paragraphs.

rior surface rises into the abdomen, as described in the pre

remain more or less unchanged in position, but the supe

When the bladder fills, the posterior surface and neck

ligaments are thickenings of the pelvic fascia.

in the female. These

pubovesical ligaments

are called the

in the male; these

puboprostatic ligaments

position by the

with those of the prostate. The neck of the bladder is held in

smooth muscle fibers of the bladder wall are continuous

upper surface of the prostate (see Fig. 7.13). Here, the

of the bladder lies inferiorly and rests on the

neck

The

above and the levator ani muscle below.

orly, they lie in contact with the obturator internus muscle

and the pubic bones. More posteri

retropubic pad of fat

are related in front to the

inferolateral surfaces

The

tate, vasa deferentia, and seminal vesicles.

Posterior view of the bladder, pros

left seminal vesicle.

Lateral view of the bladder, prostate, and

-
-

smooth muscle and is arranged as three layers of interlacing

Internal and external iliac nodes.

Lymph Drainage

the internal iliac vein.

that drains into

vesical venous plexus

The veins form the

Veins

internal iliac arteries.

The superior and inferior vesical arteries, branches of the

Arteries

sphincter vesicae.

ened to form the

bladder, the circular component of the muscle coat is thick

At the neck of the

detrusor muscle.

bundles known as the

Blood Supply

Basic Anatomy

the first and second lumbar segments of the spinal cord.

sympathetic nerves via the hypogastric plexuses and enter

vic splanchnic nerves. Some afferent fibers travel with the

in the bladder reach the central nervous system via the pel

postganglionic neurons. Most afferent sensory fibers arising

plexuses to reach the bladder wall, where they synapse with

sacral nerves; they pass through the inferior hypogastric

pelvic splanchnic nerves from the second, third, and fourth

uses. The parasympathetic preganglionic fibers arise as the

ganglia and descend to the bladder via the hypogastric plex

ganglionic fibers originate in the 1st and 2nd lumbar

The inferior hypogastric plexuses. The sympathetic post

Nerve Supply

273

bladder wall

spinal cord

L1 and 2

S2, 3, and 4

sphincter urethrae

prostate

sphincter vesicae

FIGURE 7.14

Nervous control of the bladder. Sympathetic

rusor muscle of the bladder wall and stimulate closure of

The sympathetic nerves* inhibit contraction of the det

fibers have been omitted for simplification.

the sphincter vesicae. The parasympathetic nerves stimulate

the second, third, and fourth sacral segments and pass

Efferent parasympathetic impulses leave the cord from

second lumbar segments of the spinal cord.

nerves via the hypogastric plexuses and enter the first and

7.14). Some afferent impulses travel with the sympathetic

the 2nd, 3rd, and 4th sacral segments of the spinal cord (Fig.

ent impulses pass up the pelvic splanchnic nerves and enter

individual has a conscious desire to micturate. Most affer

transmit impulses to the central nervous system, and the

stretch receptors in the bladder wall are stimulated and

is initiated when the volume of urine reaches about 300 mL;

vidual, is controlled by higher centers in the brain. The reflex

Micturition is a reflex action that, in the toilet-trained indi

Micturition

inhibit the action of the sphincter vesicae.

contraction of the detrusor muscle of the bladder wall and

via the parasympathetic preganglionic nerve fibers through

adult, this simple stretch reflex is inhibited by the activity

takes place whenever the bladder becomes distended. In the

In young children, micturition is a simple reflex act and

pelvic pressures and exert external pressure on the bladder.

the abdominal muscles to raise the intra-abdominal and

reflex action. Micturition can be assisted by contraction of

pass to the spinal cord from the urethra and reinforce the

Once urine enters the urethra, additional afferent impulses

pudendal nerve (S2, 3, and 4), and this undergoes relaxation.

Efferent impulses also pass to the urethral sphincter via the

made to contract, and the sphincter vesicae is made to relax.

smooth muscle of the bladder wall (the detrusor muscle) is

ganglionic neurons. By means of this nervous pathway, the

plexuses to the bladder wall, where they synapse with post

the pelvic splanchnic nerves and the inferior hypogastric

* The sympathetic nerves to the detrusor muscle are now thought to

entering the bladder.

about by sympathetic action), thus preventing seminal fluid from

active contraction of the bladder neck during ejaculation (brought

ever, in males, the sympathetic innervation of the sphincter causes

contraction of the sphincter in maintaining urinary continence. How

the sphincter vesicae are thought to play only a minor role in causing

are distributed mainly to the blood vessels. The sympathetic nerves to

have little or no action on the smooth muscle of the bladder wall and

Ureteric Calculi

der. In the male, one hand is placed on the anterior abdominal

of the empty bladder with or without a

Bimanual palpation

The full bladder in the adult projects up into the abdomen and

Ureteric calculi are discussed on page 212. The ureter is nar-

rowed anatomically where it bends down into the pelvis at the

pelvic brim and where it passes through the bladder wall. It is at

these sites that urinary stones may be arrested.

When a calculus enters the lower pelvic part of the ureter,

the pain is often referred to the testis and the tip of the penis in

the male and the labium majus in the female.

Palpation of the Urinary Bladder

may be palpated through the anterior abdominal wall above the

symphysis pubis.

general anesthetic is an important method of examining the blad-

wall above the symphysis pubis, and the gloved index finger of

C L I N I C A L N O T E S

(continued)

Basic Anatomy

without interruption from one organ to the other. The

the neck of the bladder, the smooth muscle passing

The base of the prostate is continuous with

Superiorly:

Relations

margins of the prostatic utricle (see Fig. 7.16).

the prostate to open into the prostatic urethra at the lateral

tory ducts pierce the upper part of the posterior surface of

against the urogenital diaphragm below. The two ejacula

which lies

apex,

lies against the bladder neck above, and an

which

Fig. 7.16). The somewhat conical prostate has a

The prostate is surrounded by a fibrous capsule (see

above and the urogenital diaphragm below (see Fig. 7.16).

1.25 in. (3 cm) long and lies between the neck of the bladder

rounds the prostatic urethra (see Figs. 7.4 and 7.16). It is about

The prostate is a fibromuscular glandular organ that sur

Location and Description

the prostatic urethra.

tatic utricle; their function is to drain the seminal fluid into

static part of the urethra, close to the margins of the pros

the posterior surface of the prostate and open into the pro

the seminal vesicle (Fig. 7.16). The ejaculatory ducts pierce

are formed by the union of the vas deferens and the duct of

The two ejaculatory ducts are each <1 in. (2.5 cm) long and

thus washing the spermatozoa out of the urethra.

contract and expel their contents into the ejaculatory ducts,

the spermatozoa. During ejaculation, the seminal vesicles

that is added to the seminal fluid. The secretions nourish

The function of the seminal vesicles is to produce a secretion

Function

The internal iliac nodes.

Lymph Drainage

The veins drain into the internal iliac veins.

Veins

The inferior vesicle and middle rectal arteries.

Arteries

embedded in connective tissue.

Each seminal vesicle consists of a much-coiled tube

ejaculatory duct.

the same side to form the

each seminal vesicle narrows and joins the vas deferens of

vesicles are related to the rectum (see Fig. 7.4). Inferiorly,

terminal part of the vas deferens. Posteriorly, the seminal

(see Fig. 7.13). On the medial side of each vesicle lies the

(5 cm) long lying on the posterior surface of the bladder

The seminal vesicles are two lobulated organs about 2 in.

Seminal Vesicles

ejaculatory duct.

the duct of the seminal vesicle to form the

The inferior end of the ampulla narrows down and joins

ampulla of the vas deferens.

deferens is dilated to form the

of the bladder (see Fig. 7.11). The terminal part of the vas

275

Blood Supply

Ejaculatory Ducts

-
-

Prostate

base,

■

bladder wall

sphincter vesicae

prostate

sphincter urethrae

spinal cord

FIGURE 7.15

then runs medially and downward on the posterior surface

the ureter in the region of the ischial spine. The vas deferens

and backward on the lateral wall of the pelvis and crosses

epigastric artery (see Fig. 7.11). It then passes downward

nal ring and passes around the lateral margin of the inferior

through the inguinal canal. It emerges from the deep ingui

from the lower end or tail of the epididymis and passes

epididymis to the ejaculatory duct and the urethra. It arises

(45 cm) long that conveys mature sperm from the

The vas deferens is a thick-walled tube about 18 in.

Vas Deferens

are described on page 131.

epididymides

testes

The

during the second or third year of life.

Voluntary control of micturition is normally developed

which compresses the bladder neck.

closes the urethra; this is assisted by the sphincter vesicae,

accomplished by contracting the sphincter urethrae, which

segments of the cord. Voluntary control of micturition is

with the corticospinal tracts to the 2nd, 3rd, and 4th sacral

rition are favorable. The inhibitory fibers pass downward

of the cerebral cortex until the time and place for mictu

omitted for clarity.

to the bladder are shown; the sympathetic fibers have been

ous system and the parasympathetic efferent fibers passing

sensory fibers from the bladder entering the central nerv

The afferent

of the spinal cord in the upper thoracic region. Destruction

Nervous control of the bladder after section

of the sacral segments of the spinal cord. B.

Male Genital Organs

and