Blood supply and Lymphatics and Nerves of the pelvis pdf - Pelvis

254

CHAPTER 6

The piriformis muscle (Fig. 6.18)

Posteriorly:

and the rectum (Fig. 6.12)

The internal iliac vessels and their branches

Anteriorly:

foramina.

the sacral nerves as they emerge from the anterior sacral

lumbosacral trunk passes down into the pelvis and joins

. The

lumbosacral trunk

fifth lumbar nerve to form the

nerves (Fig. 6.19). The fourth lumbar nerve joins the

anterior rami of the first, second, third, and fourth sacral

anterior rami of the 4th and 5th lumbar nerves and the

of the piriformis muscle (Fig. 6.18). It is formed from the

The sacral plexus lies on the posterior pelvic wall in front

The Pelvis: Part I—The Pelvic Walls

Nerves of the Pelvis

Sacral Plexus

Relations

■

aorta

aortic plexus

lumbosacral trunk

obturator nerve

sacral
plexus

pudendal nerve

piriformis muscle

coccygeus muscle

obturator nerve

median sacral artery

pelvic sympathetic trunk

right and left inferior
hypogastric plexuses

internal iliac artery

external iliac artery

common iliac artery

superior hypogastric plexus

lumbar sympathetic trunk

aortic plexus

umbosacral trunk

nerve

l nerve

s muscle

ccygeus muscle

obturator nerve

pelvic sympathetic

right and left
hypogastric p

internal

superior hypogastric plexu

lumbar sympathetic trunk

FIGURE 6.18

Posterior pelvic wall showing the sacral plexus, superior hypogastric plexus, and right and left inferior hypogas

the greater sciatic foramen (Fig. 6.12):

Branches to the lower limb that leave the pelvis through

Branches

tric plexuses. Pelvic parts of the sympathetic trunks are also shown.

■

The

(Fig. 6.9)

branch of the plexus and the largest nerve in the body

(L4 and 5; S1, 2, and 3), the largest

sciatic nerve

The

muscles

teus medius and minimus and the tensor fasciae latae

, which supplies the glu

superior gluteal nerve

The

teus maximus muscle

, which supplies the glu

inferior gluteal nerve

The

also supplies the inferior gemellus muscle

, which

nerve to the quadratus femoris muscle

The

also supplies the superior gemellus muscle

, which

nerve to the obturator internus muscle

The

perineum:

Branches to the pelvic muscles, pelvic viscera, and

plies the skin of the buttock and the back of the thigh

, which sup

posterior cutaneous nerve of the thigh

■

The

perineum through the lesser sciatic foramen (Fig. 6.12)

vis through the greater sciatic foramen and enters the

(S2, 3, and 4), which leaves the pel

pudendal nerve

The nerves to the piriformis muscle

The

summarized in Table 6.2.

The branches of the sacral plexus and their distribution are

skin of the lower medial part of the buttock

, which supplies the

perforating cutaneous nerve

The

are distributed to the pelvic viscera.

from the second, third, and fourth sacral nerves. They

sacral part of the parasympathetic system and arise

, which constitute the

pelvic splanchnic nerves

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

Fascial Ligaments of the Uterine Cervix

cervix are of particular clinical importance because they

In the female, the fascial ligaments attached to the uterine

assist with the support of the uterus and thus prevent uter-

ine prolapse (see page 288). The visceral pelvic fascia around

the uterine cervix and vagina is commonly referred to as the
parametrium.

Basic Anatomy

255

posterior cutaneous
nerve of the thigh

lumbosacral trunk

superior gluteal nerve

inferior gluteal nerve

nerve to obturator internus

nerve to quadratus femoris

sciatic nerve

common peroneal nerve

tibial nerve

perforating cutaneous nerve

pudendal nerve

FIGURE 6.19

Sacral plexus.

joint and runs forward on the lateral pelvic wall in the angle

down into the pelvis. It crosses the front of the sacroiliac

in the abdomen, and accompanies the lumbosacral trunk

and 4), emerges from the medial border of the psoas muscle

The obturator nerve is a branch of the lumbar plexus (L2, 3,

Obturator Nerve

iliac joint and joins the sacral plexus.

now enters the pelvis by passing down in front of the sacro

the lumbosacral trunk (Figs. 6.18 and 6.19). This trunk

joins the anterior ramus of the 5th lumbar nerve to form

emerges from the medial border of the psoas muscle and

Part of the anterior ramus of the fourth lumbar nerve

Lumbosacral Trunk

Branches of the Lumbar Plexus

between the internal and external iliac vessels (Fig. 6.12).

promontory of the sacrum (Fig. 6.18). It is formed as a

The superior hypogastric plexus is situated in front of the

Superior Hypogastric Plexus

of the anal canal.

the large bowel from the left colic flexure to the upper half

along branches of the inferior mesenteric artery to supply

inferior mesenteric plexus. The fibers are then distributed

hypogastric plexuses and thence via the aortic plexus to the

Some of the parasympathetic fibers ascend through the

plexus or in the walls of the viscera.

nerves and synapse in ganglia in the inferior hypogastric

preganglionic fibers arise from the 2nd, 3rd and 4th sacral

part of the autonomic nervous system in the pelvis. The

The pelvic splanchnic nerves form the parasympathetic

Pelvic Splanchnic Nerves

Fibers that join the hypogastric plexuses

nerves

Gray rami communicantes to the sacral and coccygeal

Branches

finally unite in front of the coccyx.

tally arranged ganglia. Below, the two trunks converge and

foramina. The sympathetic trunk has four or five segmen

on the front of the sacrum, medial to the anterior sacral

inal part (Fig. 6.18). It runs down behind the rectum

above, behind the common iliac vessels, with the abdom

The pelvic part of the sympathetic trunk is continuous

Pelvic Part of the Sympathetic Trunk

lateral wall of the pelvis.

Sensory branches supply the parietal peritoneum on the

Branches

is considered on page 465.

thigh. The distribution of the obturator nerve in the thigh

pass through the canal to enter the adductor region of the

brane), it splits into anterior and posterior divisions that

obturator foramen, which is devoid of the obturator mem

On reaching the obturator canal (i.e., the upper part of the

Autonomic Nerves

■

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

Sacral Plexus

ments of the cord as they emerge from the dura mater. The

endings, leading to referred pain down the inner side of the right

into the pelvic cavity could cause irritation of the obturator nerve

plies the parietal peritoneum. An inflamed appendix hanging down

The discomfort, caused by pressure from the fetal head, is often

comfort or aching pain extending down one of the lower limbs.

During the later stages of pregnancy, when the fetal head has

Pressure from the Fetal Head

descended into the pelvis, the mother often complains of dis-

relieved by changing position, such as lying on the side in bed.
Invasion by Malignant Tumors
The nerves of the sacral plexus can become invaded by malig-

nant tumors extending from neighboring viscera. A carcinoma

of the rectum, for example, can cause severe intractable pain

down the lower limbs.

Referred Pain from the Obturator Nerve

The obturator nerve lies on the lateral wall of the pelvis and sup-

thigh. Inflammation of the ovaries can produce similar symptoms.

Caudal Anesthesia (Analgesia)

Anesthetic solutions can be injected into the sacral canal

through the sacral hiatus. The solutions then act on the spinal

roots of the 2nd, 3rd, 4th and 5th sacral and coccygeal seg-

roots of higher spinal segments can also be blocked by this

method. The needle must be confined to the lower part of the

sacral canal, because the meninges extend down as far as the

lower border of the second sacral vertebra. Caudal anesthe-

sia is used in obstetrics to block pain fibers from the cervix of

the uterus and to anesthetize the perineum.

256

CHAPTER 6

deep circumflex

inferior epigastric

and gives off the

the psoas muscle, following the pelvic brim (Fig. 6.12),

The external iliac artery runs along the medial border of

nal iliac arteries (Figs. 6.12 and 6.18).

the sacroiliac joint by dividing into the external and inter

Each common iliac artery ends at the pelvic inlet in front of

cera via small subsidiary plexuses.

and visceral afferent fibers. Branches pass to the pelvic vis

preganglionic and postganglionic parasympathetic fibers,

nic nerve. It contains postganglionic sympathetic fibers,

superior hypogastric plexus) and from the pelvic splanch

Each plexus is formed from a hypogastric nerve (from the

rectum, the base of the bladder, and the vagina (Fig. 6.18).

The inferior hypogastric plexuses lie on each side of the

Inferior Hypogastric Plexuses

nerves

left hypogastric

and

right

divides inferiorly to form the

ceral afferent nerve fibers. The superior hypogastric plexus

pathetic and sacral parasympathetic nerve fibers and vis

3rd and 4th lumbar sympathetic ganglia. It contains sym

continuation of the aortic plexus and from branches of the

artery to the vas deferens

male; it also gives off the

the bladder and the prostate and seminal vesicles in the

This artery supplies the base of

Inferior vesical artery:

leaves the pelvis through the obturator canal.

lateral wall of the pelvis with the obturator nerve and

This artery runs forward along the

Obturator artery:

supplies the upper portion of the bladder (Fig. 6.12).

, which

superior vesical artery

umbilical artery arises the

From the proximal patent part of the

Umbilical artery:

Branches of the Anterior Division

usual arrangement is shown in Diagram 6.1.

gin of the terminal branches is subject to variation, but the

the perineum, the pelvic walls, and the buttocks. The ori

The branches of these divisions supply the pelvic viscera,

divides into anterior and posterior divisions (Fig. 6.12).

the upper margin of the greater sciatic foramen, where it

The internal iliac artery passes down into the pelvis to

Internal Iliac Artery

Median sacral artery

Ovarian artery

Superior rectal artery

Internal iliac artery

The following arteries enter the pelvic cavity:

Arteries of the True Pelvis

femoral artery

inguinal ligament to become the

branches. It leaves the false pelvis by passing under the

The Pelvis: Part I—The Pelvic Walls

iliac

■

-
-

Arteries of the Pelvis

Common Iliac Artery

External Iliac Artery

and

half of anal canal, perianal skin, skin of penis, scrotum, clitoris, and labia majora and

Muscles of perineum including the external anal sphincter, mucous membrane of lower

digitorum brevis muscles; skin over cleft between first and second toes. The superficial

extensor hallucis longus, extensor digitorum longus, peroneus tertius, and extensor

Biceps femoris muscle (short head) and via deep peroneal branch: tibialis anterior,

muscles of sole of foot; sural branch supplies skin on lateral side of leg and foot

digitorum longus, flexor hallucis longus, and via medial and lateral plantar branches to

[hamstring part]), gastrocnemius, soleus, plantaris, popliteus, tibialis posterior, flexor

Tibial portion

Skin over posterior surface of thigh and popliteal fossa, also over lower part of buttock,

Branches

Distribution

Superior gluteal nerve

Gluteus medius, gluteus minimus, and tensor fasciae latae muscles

Inferior gluteal nerve

Gluteus maximus muscle

Nerve to piriformis

Piriformis muscle

Nerve to obturator internus

Obturator internus and superior gemellus muscles

Nerve to quadratus femoris

Quadratus femoris and inferior gemellus muscles

Perforating cutaneous nerve

Skin over medial aspect of buttock

Posterior cutaneous nerve of thigh

scrotum, or labium majus

Sciatic nerve (L4, 5; S1, 2, 3)

Hamstring muscles (semitendinous, biceps femoris [long head], adductor magnus

Common peroneal portion

peroneal branch supplies the peroneus longus and brevis muscles and skin over lower

third of anterior surface of leg and dorsum of foot

Pudendal nerve

minora

Branches of the Sacral Plexus and their Distribution

T A B L E 6 . 2

Basic Anatomy

not enter the pelvis.) The ovarian artery arises from

(The testicular artery enters the inguinal canal and does

Ovarian Artery

membrane of the rectum and the upper half of the anal canal.

crosses the common iliac artery. It supplies the mucous

rior mesenteric artery. The name changes as the latter artery

The superior rectal artery is a direct continuation of the infe

Superior Rectal Artery

muscle. It supplies the gluteal region.

through the greater sciatic foramen above the piriformis

This artery leaves the pelvis

Superior gluteal artery:

structures (Fig. 6.12).

of the sacral plexus, giving off branches to neighboring

These arteries descend in front

Lateral sacral arteries:

acus muscles.

inlet posterior to the external iliac vessels, psoas, and ili

This artery ascends across the pelvic

Iliolumbar artery:

Branches of the Posterior Division

vagina and the base of the bladder.

inferior vesical artery present in the male. It supplies the

This artery usually takes the place of the

Vaginal artery:

ine artery gives off a vaginal branch.

where it anastomoses with the ovarian artery. The uter

uterus. It ends by following the uterine tube laterally,

of the broad ligament along the lateral margin of the

reach the uterus. Here, it ascends between the layers

7.28). It passes above the lateral fornix of the vagina to

(see Fig.

crosses the ureter superiorly

of the pelvis and

This artery runs medially on the floor

Uterine artery:

or second and third sacral nerves.

muscle (Fig. 6.12). It passes between the first and second

through the greater sciatic foramen below the piriformis

This artery leaves the pelvis

Inferior gluteal artery:

of the anal canal and the skin and muscles of the perineum.

the pudendal nerve. Its branches supply the musculature

foramen and passes forward in the pudendal canal with

enters the perineum by passing through the lesser sciatic

teal region below the piriformis muscle (Fig. 6.12). It then

through the greater sciatic foramen and enters the glu

This artery leaves the pelvis

Internal pudendal artery:

rior rectal and inferior rectal arteries.

cle of the lower rectum and anastomoses with the supe

the inferior vesical artery (Fig. 6.12). It supplies the mus

Commonly, this artery arises with

Middle rectal artery:

iliac nodes

common

, and

internal iliac nodes

external iliac nodes

are

blood vessels with which they are associated. Thus, there

the main blood vessels. The nodes are named after the

The lymph nodes and vessels are arranged in a chain along

Lymphatics of the Pelvis

artery and end by joining the left common iliac vein.

The median sacral veins accompany the corresponding

Median Sacral Veins

vein (Fig. 6.12).

and joins the external iliac vein to form the common iliac

iliac artery. It passes upward in front of the sacroiliac joint

tributaries that correspond to the branches of the internal

The internal iliac vein begins by the joining together of

Internal Iliac Vein

deep circumflex iliac veins

inferior epigastric

(Fig. 6.12). It receives

common iliac vein

vein to form the

side of the corresponding artery and joins the internal iliac

a continuation of the femoral vein. It runs along the medial

The external iliac vein begins behind the inguinal ligament as

External Iliac Vein

Veins of the Pelvis

Chapter 7.

arteries is discussed in detail with the individual viscera in

The distribution of the visceral branches of the pelvic

anterior surface of the sacrum and coccyx.

bifurcation of the aorta (Fig. 6.18). It descends over the

The median sacral artery is a small artery that arises at the

Median Sacral Artery

way of the mesovarium.

passes into the broad ligament and enters the ovary by

enters the suspensory ligament of the ovary. It then

It crosses the external iliac artery at the pelvic inlet and

passes downward and laterally behind the peritoneum.

lumbar vertebra. The artery is long and slender and

the abdominal part of the aorta at the level of the first

257

the

and

■

-
-

■

Anterior division

Posterior division

Umbilical artery

Obturator artery
Inferior vesical artery
Middle rectal artery
Internal pudendal artery
Inferior gluteal artery
Uterine artery (female)
Vaginal artery (female)
Iliolumbar artery
Lateral sacral artery
Superior gluteal artery

artery to vas deferens (male)
superior vesical artery

DIAGRAM 6.1

Branches of the Internal Iliac Artery