Post on 02-Apr-2018
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PELVIC WALL
JOINTS OF THE PELVISPELVIC FLOOR
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PELVIC WALL
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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.
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The Pelvis
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5
The bony pelvis provides
a strong, stable
connection between the
trunk and the lower
extremities.
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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.
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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.
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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.
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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.
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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.
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ORIENTATION OFTHE PELVIS
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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.
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FALSE PELVIS
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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.
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TRUE PELVIS
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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.
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Dr. L. Tchakarov 17
The true pelvis has:
an inlet,
an outlet, and a cavity.
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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.
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Dr. L. Tchakarov 19
The pelvic outlet is bounded:
posteriorly by the coccyx,
laterally by the ischial tuberosities, and
anteriorly by the pubic arch.
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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.
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Dr. L. Tchakarov 21
The sciatic notches are
divided by the
sacrotuberous andsacrospinous
ligaments into the
greater and lesser
sciatic foramina.
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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.
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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.
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Structure of thePelvic Walls
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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.
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ANTERIOR PELVICWALL
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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.
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POSTERIOR PELVICWALL
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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.
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Sacrum
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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.
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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.
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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.
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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.
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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.
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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.
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Dr. L. Tchakarov 37
The sacrum is usually wider in proportion to
its length in the female than in the male.
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Dr. L. Tchakarov 38
The sacrum is tilted
forward so that it
forms an angle withthe fifth lumbar
vertebra, called the
lumbosacral angle.
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Coccyx
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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.
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Piriformis Muscle
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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.
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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.
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LATERAL PELVICWALL
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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.
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Hip Bone
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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.
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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.
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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.
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Dr. L. Tchakarov 50
The sciatic notches
are converted into
thegreater and
lesser sciatic
foramina
by the presence of
the sacrotuberous
and sacrospinous
ligaments.
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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.
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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.
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Dr. L. Tchakarov 53
The ischiumis the inferior and posterior part
of the hip bone and possesses an ischial spine
and anischial tuberosity.
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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.
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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.
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Obturator Membrane
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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.
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SacrotuberousLigament
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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.
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SacrospinousLigament
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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.
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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.
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Obturator InternusMuscle
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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.
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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.
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INFERIOR PELVIC WALL,OR PELVIC FLOOR
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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.
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PELVIC DIAPHRAGM
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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.
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Levator Ani Muscle
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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.
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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
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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.
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Dr. L. Tchakarov 74
2. Intermediate fibers:
The puborectalisforms a sling around the
junction of the rectum and anal canal.
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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.
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Dr. L. Tchakarov 76
3. Posterior fibers:
The iliococcygeusis inserted into the
anococcygeal body and the coccyx.
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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.
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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).
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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.
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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.
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Coccygeus Muscle
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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.
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IN BRIEF
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Dr. L. Tchakarov 84
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Pelvic Fascia
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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.
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PARIETAL PELVICFASCIA
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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
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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.
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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.
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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.
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VISCERAL LAYER OFPELVIC FASCIA
The visceral layer
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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.
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Pelvic Peritoneum
The parietal peritoneum lines
the pelvic walls and is reflected
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Dr. L. Tchakarov 95
the pelvic walls and is reflected
onto the pelvic viscera, where it
becomes continuous with the
visceral peritoneum.
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MALE V/S FEMALE
PELVIS
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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.
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THE END