Pelvic Wall, Joints and Floor

7/27/2019 Pelvic Wall, Joints and Floor

1/98

PELVIC WALL

JOINTS OF THE PELVISPELVIC FLOOR


2/98

PELVIC WALL


3/98

Dr. L. Tchakarov 3

The pelvis is the

region of the

trunk that lies

below the

abdomen.

Although the

abdominal and

pelvic cavities

are continuous,

the two regions

are describedseparately.


4/98

The Pelvis


5/98

5

The bony pelvis provides

a strong, stable

connection between the

trunk and the lower

extremities.


6/98

6

The main functions of the pelvis are:

1. to transmit the weight of the body

from the vertebral column to the

femurs;

2. to contain, support, and protect

the pelvic viscera; and

3. to provide attachment for trunk

and lower limb muscles.


7/98Dr. L. Tchakarov 7

The bony pelvis is composed of four bones:

the two hip bones,which form the lateral and

anterior walls, and

the sacrumand the coccyx,which are part of the

vertebral column and form the back wall.



The two hip bones articulate with each other anteriorly at the

symphysis pubisand posteriorly with the sacrum at the sacroiliac

joints.

The bony pelvis with its joints form a strong basin-shaped structure

that contains and protects the lower parts of the intestinal and

urinary tracts and the internal organs of reproduction.



The pelvis is divided into two parts by the pelvic brim.

Above the brim is the false pelvis,which forms part of the

abdominal cavity.

Below the brim is the true pelvis.



The pelvic brim is formed by:

the sacral promontory(anterior and upper margin of the first sacral

vertebra) behind,

the ileopectineal lines(a line that runs downward and forward around

the inner surface of the ileum) laterally, and

the symphysis pubis(joint between bodies of pubic bones) anteriorly.


11/98

ORIENTATION OFTHE PELVIS



In the standard anatomic position, the front of the symphysis

pubis and the anterior superior iliac spines lie in the same

vertical plane.

This means that the pelvic surface of the symphysis pubis faces

upward and backward and the anterior surface of the sacrum is

directed forward and downward.


13/98

FALSE PELVIS


14/98

Dr. L. Tchakarov 14

The false pelvis isbounded behind by thelumbar vertebrae,laterally by the iliac

fossae and the iliacusmuscles, and in front bythe lower part of theanterior abdominal wall.

The false pelvis flares out

at its upper end andshould be considered aspart of the abdominalcavity.

It supports the abdominalcontents and after the

third month of pregnancyhelps support the graviduterus.

During the early stages oflabor, it helps guide thefetus into the true pelvis.


15/98

TRUE PELVIS


16/98

Dr. L. Tchakarov 16

Knowledge of the shape and dimensions of the female pelvis

is ofgreat importance for obstetrics, because it is the bony

canal through which the child passes during birth.


17/98

Dr. L. Tchakarov 17

The true pelvis has:

an inlet,

an outlet, and a cavity.


18/98

Dr. L. Tchakarov 18

The pelvic inlet, or pelvic brim,is bounded posteriorly

by the sacral promontory, laterally by the iliopectineal

lines, and anteriorly by the symphysis pubis.


19/98

Dr. L. Tchakarov 19

The pelvic outlet is bounded:

posteriorly by the coccyx,

laterally by the ischial tuberosities, and

anteriorly by the pubic arch.


20/98

Dr. L. Tchakarov 20

The pelvic outlet does not present a smooth outline but has three

wide notches:

Anteriorly, the pubic arch is between the ischiopubic rami, and,

laterally, are the sciatic notches.


21/98

Dr. L. Tchakarov 21

The sciatic notches are

divided by the

sacrotuberous andsacrospinous

ligaments into the

greater and lesser

sciatic foramina.


22/98

Dr. L. Tchakarov 22

From an obstetric standpoint, because the sacrotuberous

ligaments are strong and relatively inflexible, they should beconsidered to form part of the perimeter of the pelvic outlet.

Thus the outlet is diamond shaped, with the ischiopubic rami

and the symphysis pubis forming the boundaries in front and the

sacrotuberous ligaments and the coccyx forming the boundaries

behind.


23/98

Dr. L. Tchakarov 23

The pelvic cavitylies

between the inlet and

the outlet.

It is a short, curved

canal, with a shallow

anterior wall and a much

deeper posterior wall.


24/98

Structure of thePelvic Walls


25/98

Dr. L. Tchakarov 25

The walls of the

pelvis are formed bybones and ligaments

that are partly lined

with muscles

covered with fascia

and parietalperitoneum.

The pelvis has

anterior, posterior,

and lateral walls

and an inferior wallor floor.


26/98

ANTERIOR PELVICWALL


27/98

Dr. L. Tchakarov 27

The anterior

pelvic wall is the

shallowest wall

and is formed by

the posteriorsurfaces of the

bodies of the

pubic bones, the

pubic rami, and

the symphysis

pubis.


28/98

POSTERIOR PELVICWALL


29/98

Dr. L. Tchakarov 29

The posterior pelvic wall is extensive and is formed

by the sacrum and coccyx and by the piriformis

muscles and their covering of parietal pelvic fascia.


30/98

Sacrum


31/98

Dr. L. Tchakarov 31

The sacrum consists offive rudimentary

vertebrae fused together

to form a single wedge-

shaped bone with a

forward concavity.

The upper border or base

of the bone articulates

with the fifth lumbar

vertebra.

The narrow inferior border

articulates with the

coccyx.


32/98

Dr. L. Tchakarov 32

Laterally, the sacrum articulates with the two iliac bones toform the sacroiliac joints.

The anterior and upper margins of the first sacral vertebra bulge

forward as the posterior margin of the pelvic inletthe sacral

promontorywhich is an important obstetric landmark used

when measuring the size of the pelvis.


33/98

Dr. L. Tchakarov 33

The vertebral foramina together form the sacral canal.

The laminae of the fifth sacral vertebra, and sometimes those of

the fourth, fail to meet in the midline, forming the sacral hiatus.


34/98

Dr. L. Tchakarov 34

The sacral canal contains the

anterior and posterior roots

of the lumbar, sacral, and

coccygeal spinal nerves; the

filum terminale; and

fibrofatty material.


35/98

Dr. L. Tchakarov 35

The sacral canal also contains the lower part of the

subarachnoid space down as far as the lower

border of the second sacral vertebra.


36/98

Dr. L. Tchakarov 36

The anterior and posterior surfaces of the sacrum possess

on each side four foramina for the passage of the anterior

and posterior rami of the upper four sacral nerves.


37/98

Dr. L. Tchakarov 37

The sacrum is usually wider in proportion to

its length in the female than in the male.


38/98

Dr. L. Tchakarov 38

The sacrum is tilted

forward so that it

forms an angle withthe fifth lumbar

vertebra, called the

lumbosacral angle.


39/98

Coccyx


40/98

Dr. L. Tchakarov 40

The coccyx consists of four vertebrae fused together to

form a small triangular bone, which articulates at its

base with the lower end of the sacrum.

The coccygeal vertebrae consist of bodies only, but thefirst vertebra possesses a rudimentary transverse

process and cornua.

The cornua are the remains of the pedicles and

superior articular processes and project upward to

articulate with the sacral cornua.


41/98

Piriformis Muscle


42/98

Dr. L. Tchakarov 42

The piriformis muscle arises from the front of the lateralmasses of the sacrum and leaves the pelvis to enter the gluteal

region by passing laterally through the greater sciatic foramen.

It is inserted into the upper border of the greater trochanter of

the femur.


43/98

Dr. L. Tchakarov 43

Action: It is a lateral rotator of the femur at the hip joint.

Nerve supply:It receives branches from the sacral plexus.


44/98

LATERAL PELVICWALL


45/98

Dr. L. Tchakarov 45

The lateral pelvic wall is formed by part of the hip

bone below the pelvic inlet, the obturator membrane,

the sacrotuberous and sacrospinous ligaments, and the

obturator internus muscle and its covering fascia.


46/98

Hip Bone


47/98

Dr. L. Tchakarov 47

In children, each hip

bone consists of the

ilium, which liessuperiorly; the ischium,

which lies posteriorly

and inferiorly; and the

pubis, which lies

anteriorly and inferiorly. The three separate

bones are joined by

cartilage at the

acetabulum.

At puberty, these threebones fuse together to

form one large, irregular

bone.


48/98

Dr. L. Tchakarov 48

The hip bones articulate with the sacrum at the sacroiliac

joints and form the anterolateral walls of the pelvis; they also

articulate with one another anteriorly at the symphysis pubis.


49/98

49

On the outer surface of the hip bone is a deepdepression, the acetabulum, which articulates with

the hemispherical head of the femur.

Behind the acetabulum is a large notch, the

greater sciatic notch,which is separated from the

lesser sciatic notchby the spine of the ischium.


50/98

Dr. L. Tchakarov 50

The sciatic notches

are converted into

thegreater and

lesser sciatic

foramina

by the presence of

the sacrotuberous

and sacrospinous

ligaments.


51/98

Dr. L. Tchakarov 51

The ilium,which is the upper flattened part ofthe hip bone, possesses the iliac crest.

The iliac crest runs between the anterior and

posterior superior iliac spines.

Below these spines are the corresponding

anteriorand posterior inferior iliac spines.


52/98

Dr. L. Tchakarov 52

On the inner surface of the ilium is the large auricular surfacefor articulation with the sacrum.

The iliopectineal lineruns downward and forward around the

inner surface of the ilium and serves to divide the false from

the true pelvis.


53/98

Dr. L. Tchakarov 53

The ischiumis the inferior and posterior part

of the hip bone and possesses an ischial spine

and anischial tuberosity.


54/98

Dr. L. Tchakarov 54

The pubisis the anterior part of the hip bone and hasa bodyand superiorandinferior pubic rami.

The body of the pubis bears the pubic crestand the

pubic tubercleand articulates with the pubic bone

of the opposite side at the symphysis pubis.


55/98

Dr. L. Tchakarov 55

In the lower part of the hip bone is a large opening, the obturator

foramen,which is bounded by the parts of the ischium and pubis.

The obturator foramen is filled in by the obturator membrane.


56/98

Obturator Membrane


57/98

Dr. L. Tchakarov 57

The obturator membrane is a fibrous sheet that almost

completely closes the obturator foramen, leaving a small gap,

the obturator canal, for the passage of the obturator nerve

and vessels as they leave the pelvis to enter the thigh.


58/98

SacrotuberousLigament


59/98

Dr. L. Tchakarov 59

The sacrotuberous ligament is strong and extends from

the lateral part of the sacrum and coccyx and the

posterior inferior iliac spine to the ischial tuberosity.


60/98

SacrospinousLigament


61/98

Dr. L. Tchakarov 61

The sacrospinous ligament is strong and triangle shaped.

It is attached by its base to the lateral part of the sacrum

and coccyx and by its apex to the spine of the ischium.


62/98

Dr. L. Tchakarov 62

The sacrotuberous and sacrospinous ligaments prevent the lowerend of the sacrum and the coccyx from being rotated upward at

the sacroiliac joint by the weight of the body.

The two ligaments also convert the greater and lesser sciatic

notches into foramina, the greaterand lesser sciatic foramina.


63/98

Obturator InternusMuscle


64/98

Dr. L. Tchakarov 64

The obturator internus muscle arises from the pelvic surface of

the obturator membrane and the adjoining part of the hip bone.

The muscle fibers converge to a tendon, which leaves the pelvis

through the lesser sciatic foramen and is inserted into the greater

trochanter of the femur.


65/98

Dr. L. Tchakarov 65

Action:The obturator internus is a lateral rotator of the

femur at the hip joint.

Nerve supply:The muscle is supplied by the nerve to the

obturator internus, a branch from the sacral plexus.


66/98

INFERIOR PELVIC WALL,OR PELVIC FLOOR


67/98

Dr. L. Tchakarov 67

The floor of the pelvis supports the pelvic viscera and is

formed by the pelvic diaphragm.

The pelvic floor stretches across the pelvis and divides

it into the main pelvic cavityabove, which contains

the pelvic viscera, and the perineumbelow.


68/98

PELVIC DIAPHRAGM


69/98

Dr. L. Tchakarov 69

It is incomplete anteriorlyto allow passage of the urethra

in males and the urethra and the vagina in females.

The pelvic

diaphragm is

formed by the

important

levatores animuscles and the

small coccygeus

muscles and their

covering fasciae.


70/98

Levator Ani Muscle


71/98

Dr. L. Tchakarov 71

The levator ani muscle is a wide thin sheet that has a linear

origin from the back of the body of the pubis, a tendinous arch

formed by a thickening of the pelvic fascia covering the

obturator internus, and the spine of the ischium.


72/98

Dr. L. Tchakarov 72

From this extensive

origin, groups offibers sweep

downward and

medially to their

insertion, as

follows:1. Anterior fibers:

The levator

prostatae or

sphincter vaginae

form a sling aroundthe prostate or

vagina.

levator

prostatae

sphincter

vaginae


73/98

Dr. L. Tchakarov 73

They are inserted into a mass of fibrous tissue, called

the perineal body,in front of the anal canal.

The levator prostatae support the prostate and

stabilize the perineal body.

The sphincter vaginae constrict the vagina and

stabilize the perineal body.


74/98

Dr. L. Tchakarov 74

2. Intermediate fibers:

The puborectalisforms a sling around the

junction of the rectum and anal canal.


75/98

Dr. L. Tchakarov 75

The pubococcygeus passes posteriorly to be inserted

into a small fibrous mass, called the anococcygeal body,

between the tip of the coccyx and the anal canal.


76/98

Dr. L. Tchakarov 76

3. Posterior fibers:

The iliococcygeusis inserted into the

anococcygeal body and the coccyx.


77/98

Dr. L. Tchakarov 77

Action:

1. The levatores ani muscles of the two sides

form an efficient muscular sling that supports

and maintains the pelvic viscera in position.


78/98

Dr. L. Tchakarov 78

1. They resist the rise in intrapelvic pressure

during the straining and expulsive efforts of

the abdominal muscles (as occurs in coughing).


79/98

Dr. L. Tchakarov 79

1. They also have an important sphincter action on the

anorectal junction, and in the female they serve

also as a sphincter of the vagina.


80/98

Dr. L. Tchakarov 80

Nerve supply:This is from the perineal branch of the fourth

sacral nerve and from the perineal branch of the pudendal nerve.


81/98

Coccygeus Muscle


82/98

Dr. L. Tchakarov 82

This small triangular

muscle arises from the

spine of the ischiumand is inserted into the

lower end of the

sacrum and into the

coccyx.

Action:The twomuscles assist the

levatores ani in

supporting the pelvic

viscera.

Nerve supply:This isfrom a branch of the

fourth and fifth sacral

nerves.


83/98

IN BRIEF


84/98

Dr. L. Tchakarov 84


85/98

Pelvic Fascia


86/98

Dr. L. Tchakarov 86

The pelvic fascia is formed of connective tissue and is continuous

above with the fascia lining the abdominal walls.

Below, the fascia is continuous with the fascia of the perineum.

The pelvic fascia can be divided into parietal and visceral layers.


87/98

PARIETAL PELVICFASCIA


88/98

Dr. L. Tchakarov 88

The parietal pelvic fascia lines the walls of the pelvis and is

named according to the muscle it overlies.

For example, over the obturator internus muscle it is dense

and strong and is known as the obturator internus fascia.

Over the levator ani

and coccygeus muscles


89/98

Dr. L. Tchakarov 89

and coccygeus muscles

it forms the levator ani

and coccygeus fascia

or, to describe it more

concisely, the superior

fascial layer of the

pelvic diaphragm.


90/98

90

Where the pelvic diaphragm is deficient anteriorly, theparietal pelvic fascia becomes continuous through the

opening with the fascia covering the inferior surface of

the pelvic diaphragm, in the perineum.

In many locations where the parietal fascia comes into

contact with bone it fuses with the periosteum.


91/98

Dr. L. Tchakarov 91

Below in the perineum, where the parietal pelvic fascia covers the

sphincter urethrae muscle and the perineal membrane, it is known

as the perineal layer of the parietal pelvic fascia; that is, it forms

the superior fascial layer of the urogenital diaphragm.


92/98

VISCERAL LAYER OFPELVIC FASCIA

The visceral layer


93/98

93

In certain locations the fascia thickens to form fascial ligaments,

which commonly extend from the pelvic walls to a viscus and provide

it with additional support.

These ligaments are usually named according to their attachments,

for example, the pubovesical and the sacrocervical ligaments.

of pelvic fascia is a

layer of loose

connective tissue

that covers andsupports all the

pelvic viscera.

Where a particular

viscus comes into

contact with thepelvic wall, the

visceral layer fuses

with the parietal

layer.


94/98

Pelvic Peritoneum

The parietal peritoneum lines

the pelvic walls and is reflected


95/98

Dr. L. Tchakarov 95

the pelvic walls and is reflected

onto the pelvic viscera, where it

becomes continuous with the

visceral peritoneum.


96/98

MALE V/S FEMALE

PELVIS


97/98

Dr. L. Tchakarov 97

The capacity and shape of the female pelvis are of fundamental

importance in obstetrics.

The female pelvis is well adapted for the process of childbirth.

The pelvis is shallower and the bones are smoother than in themale.

The size of the pelvic inlet is similar in the two sexes; but in the

female, the cavity is larger and cylindrical and the pelvic outlet is

wider in both the anteroposterior and the transverse diameters.


98/98

THE END

Documents

Pelvic Wall, Joints and Floor