Contents of the pelvic cavity pdf - Pelvis

Basic Anatomy

263

Contents of the Pelvic Cavity

The rectum is about 5 in. (13 cm) long and begins in front

Location and Description

inferior hypogastric plexuses.

The sympathetic and parasympathetic nerves from the

Nerve Supply

inferior mesenteric nodes.

moid arteries; from these nodes, the lymph travels to the

The lymph drains into nodes along the course of the sig

Lymph Drainage

joins the portal venous system.

The veins drain into the inferior mesenteric vein, which

Veins

Sigmoid branches of the inferior mesenteric artery.

Arteries

part of the ileum.

colon is also related to the lower coils of the terminal

The rectum and the sacrum. The sigmoid

Posteriorly:

part of the vagina

female, the posterior surface of the uterus and the upper

In the male, the urinary bladder; in the

Anteriorly:

Relations

sigmoid mesocolon.

wall by the fan-shaped

The sigmoid colon is attached to the posterior pelvic

the form of a loop.

colon is mobile and hangs down into the pelvic cavity in

rectum in front of the 3rd sacral vertebra. The sigmoid

of the pelvic brim. Below, it becomes continuous with the

begins as a continuation of the descending colon in front

The sigmoid colon is 10 to 15 in. (25 to 38 cm) long and

Location and Description

Sigmoid Colon

■

Blood Supply

Rectum

of the third sacral vertebra as a continuation of the sigmoid

natomy

asic

The pelvic cavity, or cavity of the true pelvis, can be defined

into the main pelvic cavity above and the perineum below

It is customary to subdivide it by the pelvic diaphragm

as the area between the pelvic inlet and the pelvic outlet.

(Fig. 7.1). This chapter is concerned with the contents of

neum is given in Chapter 8.

the main pelvic cavity. A detailed description of the peri-

■

ectopic pregnancy, spontaneous abortion, and acute pelvic

Emergency situations involving the bladder, the pregnant uterus,

The organs project up into the peritoneal cavity, causing the

their nerve supply, blood supply, and lymphatic drainage.

■

The pelvic cavity contains the lower ends of the intestinal and

urinary tracts and the internal organs of reproduction as well as

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peritoneum to be draped over them in folds, producing impor-

tant fossae that are the sites for the accumulation of blood and

pus in different types of pelvic disease.

■

The physician is often confronted with problems involving infec-

tions, injuries, and prolapses of the rectum, uterus, and vagina.

■

inflammatory disease are examples of problems found in the

female.

■

The urinary bladder and the prostate in the male are frequent

sites of disease.

■

The purpose of this chapter is to consider the important

anatomy relative to common clinical conditions involving the

pelvic organs.

thoracic cavity

perineum

pelvic outlet

main

pelvic cavity

abdominal cavity

diaphragm

costal
margin

iliac crest

pelvic inlet

pelvic diaphragm

FIGURE 7.1

Coronal section through the thorax, abdomen,

and pelvis showing the thoracic, abdominal, and pelvic

cavities and the perineum.

C H A P T E R O B J E C T I V E S

Basic Anatomy

265

sigmoid

colon

umbilicus

area of
referred
discomfort or
pain as instrument
enters sigmoid
colon

6.5 in.

1 1/2 in.

FIGURE 7.2

Sigmoidoscopy.

thetic nerves from the inferior hypogastric plexuses. The

The nerve supply is from the sympathetic and parasympa

Nerve Supply

middle rectal artery to the internal iliac nodes.

Lymph vessels from the lower part of the rectum follow the

and then into inferior mesenteric nodes.

arectal nodes

The lymph vessels of the rectum drain first into the

Lymph Drainage

tomosis (see Chapter 5).

the rectal veins forms an important portal–systemic anas

internal pudendal veins, respectively. The union between

drain into the internal iliac and

inferior rectal veins

middle

and drains into the inferior mesenteric vein. The

is a tributary of the portal circulation

superior rectal vein

The veins of the rectum correspond to the arteries. The

Veins

middle rectal artery at the anorectal junction.

pudendal artery in the perineum. It anastomoses with the

is a branch of the internal

inferior rectal artery

The

iliac artery and is distributed mainly to the muscular coat.

is a small branch of the internal

middle rectal artery

The

another and with the middle and inferior rectal arteries.

supply the mucous membrane. They anastomose with one

right and left branches, which pierce the muscular coat and

ing in the root of the sigmoid mesocolon and divides into

ing the mucous membrane. It enters the pelvis by descend

inferior mesenteric artery and is the chief artery supply

is a direct continuation of the

superior rectal artery

The

supply the rectum.

The superior, middle, and inferior rectal arteries (Fig. 7.6)

Arteries

vagina (see Fig. 7.5).

of peritoneum, is related to the posterior surface of the

of Douglas). The lower third of the rectum, which is devoid

coils of ileum that occupy the rectouterine pouch (pouch

covered by peritoneum, is related to the sigmoid colon and

the upper two thirds of the rectum, which is

In the female,

vesicles on each side, and to the prostate (see Fig. 7.4).

der, to the termination of the vas deferens and the seminal

peritoneum, is related to the posterior surface of the blad

pouch. The lower third of the rectum, which is devoid of

moid colon and coils of ileum that occupy the rectovesical

tum, which is covered by peritoneum, is related to the sig

the upper two thirds of the rec

Anteriorly: In the male,

(see Fig. 6.18).

muscles; the sacral plexus; and the sympathetic trunks

and coccyx; the piriformis, coccygeus, and levatores ani

The rectum is in contact with the sacrum

Posteriorly:

Relations

(see Fig. 7.3); they vary in position.

transverse folds of the rectum

permanent folds called the

the circular muscle layer, forms two or three semicircular

of the rectum, together with

mucous membrane

The

band on the anterior and posterior surfaces of the rectum.

come together so that the longitudinal fibers form a broad

muscle. The three teniae coli of the sigmoid colon, however,

usual outer longitudinal and inner circular layers of smooth

of the rectum is arranged in the

muscular coat

The

toneum (Figs. 7.4 and 7.5).

of the middle third, leaving the lower third devoid of peri

of the first third of the rectum and only the anterior surface

covers the anterior and lateral surfaces

peritoneum

The

producing the anorectal angle.

with the anal canal and pulls this part of the bowel forward,

forms a sling (see page 247) at the junction of the rectum

The puborectalis portion of the levator ani muscles

canal (Fig. 7.4).

ing downward and backward at its junction with the anal

follows the anterior concavity of the sacrum before bend

to the median plane (Fig. 7.3). On lateral view, the rectum

The rectum deviates to the left, but it quickly returns

rectal ampulla.

dilated to form the

tinuous with the anal canal. The lower part of the rectum is

cyx by piercing the pelvic diaphragm and becoming con

sacrum and coccyx, and ends in front of the tip of the coc

colon. It passes downward, following the curve of the

referred to the skin of the anterior abdominal wall below the

discomfort or pain experienced by the patient as the tube

patient as it ascends the anal canal and rectum. The area of

) of the tube of the sigmoidoscope relative to the

Sagittal section of the male pelvis showing the positions

tion with the left knee flexed and the right knee extended.

Patient in the left lateral posi

(1, 2, and 3

is negotiated around the bend into the sigmoid colon is

umbilicus.

-
-

■

-
-

Blood Supply

-
-

and

par-

to stretch.

only

rectum is sensitive

266

CHAPTER 7

The Pelvis: Part II—The Pelvic Cavity

peritoneum

middle transverse

fold of rectum

obturator internus

fascia

obturator membrane

levator ani

puborectalis

outer longitudinal

muscle

internal anal

sphincter

external anal sphincter

anus

fat in ischiorectal fossa

anal canal

inferior rectal

vessels and

nerve

pudendal nerve

internal pudendal

vessels

anal column

ampulla of rectum

upper and lower

transverse folds

of rectum

outer longitudinal muscle

mucous membrane of rectum

inner circular muscle

FIGURE 7.3

Coronal section through the pelvis showing the rectum and the pelvic floor.

sigmoid colon

coil of ileum

bladder

puboprostatic

ligaments

prostate

urogenital diaphragm

scrotum

membranous layer of superficial fascia

opening of ejaculatory
duct into prostatic urethra

perineal body

anal canal

anus

internal sphincter

external sphincter

anococcygeal body

ejaculatory duct

seminal vesicle

rectum

peritoneum

rectovesical pouch

FIGURE 7.4

Sagittal section of the male pelvis.

Basic Anatomy

267

sigmoid colon

coil of ileum

cavity of uterus

uterovesical pouch

bladder

cervix

urogenital diaphragm

urethra

vagina

perineal body

anus

anal canal

anococcygeal body

rectum

rectouterine pouch

peritoneum

FIGURE 7.5

Sagittal section of the female pelvis.

superior rectal
artery

right
transverse
fold of
rectum

middle rectal
artery

RIGHT

anal
columns

external
anal
sphincter

anal
valves

anus

inferior rectal
artery

puborectalis
muscle

upper left
transverse
fold of rectum

LEFT

lower left
transverse fold
of rectum

right transverse
fold of rectum

lower left
transverse
fold of rectum

FIGURE 7.6

The transverse folds of the rectum as seen through a sigmoidoscope.

Blood supply to the rectum.