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PELVIS
It is the part of the 
body surrounded by
the pelvic bones and
the inferior
elements of the
vertebral column.
FUNCTIONS OF BONY PELVIS
1.Transmittion of body 
weight from the vertebral
column to the femora.
2. Protection and support 
of the pelvic viscera.
3. Gives attachment to the 
muscles of the lower limb
and trunk.
ORIENTATION OF THE PELVIS
It is the orientation 
of the bony pelvis
relative to the trunk.
In the anatomic 
position:
1.The front of the 
symphysis pubis and
the anterior superior
iliac spine are in the
same vertical plane.
ORIENTATION OF THE PELVIS
2. The pelvic surface
of the symphysis
pubis faces upward
and backward.
3. The anterior 
surface of the
sacrum is directed
forward and
downward.

SUBDIVISIONS OF THE PELVIS
It is divided into 
two parts by the
pelvic brim (pelvic
inlet) :
Upper large part 
(false) pelvis :
above the brim.
Lower (true) pelvis.

FALSE (GREATER) PELVIS
It is of little clinical 
importance.
It is considered part of 
the abdominal cavity.
It is bounded by : 
Posteriorly : lumbar 
vertebrae.
Laterally : iliac fossae and
iliacus muscles.
Anteriorly : lower part of
the anterior abdominal
wall.


TRUE (LESSER) PELVIS
It is cylindrical in
shape.
It has : 
An inlet. 
Walls. 
A cavity. 
Outlet. 

PELVIC ( BRIM) INLET
It is the opening 
between the
abdominal and the
pelvic cavities,
through which
structures can pass
between them.
It is opened. 
PELVIC ( BRIM) INLET
It is completely 
surrounded by
bones and joints.
Posteriorly : sacral
promontry.
Anteriorly : 
Symphysis pubis.
Laterally : Arcuate
line (iliopectineal
lines part of it).


PELVIC OUTLET
It is closed by the 
pelvic floor.
It separates the 
pelvic cavity above
from the perineum
below.
The terminal parts of
the urinary &
gastrointestinal
tracts and the vagina
pass through it.

PELVIC OUTLET
It is diamoned shaped. 
It has three notches the 
(pubic arch anteriorly &
sciatic notches
laterally).
The anterior boundary: 
Is predominantly bony 
(pubic arch & symphysis
pubis).
PELVIC OUTLET
Posterior 
boundary:
Is predominantly
ligamentous:
(sacrotuberous
ligaments &
(coccyx ).
Lateral 
boundary:
Elements of the
pubic arch.

FEMALE PELVIS
It should have the 
following criteria to
allow the passage of a
baby during labour.
(1) Pelvic inlet : 
Transversly oval (less
distinct promontry and
broader alae).
FEMALE PELVIS
(2) The angle: 
Between the two
rami of the pubic arch
: (80-85).
(3) The ischial 
spines:
Do not project so far 
medially.
(4) The false pelvis: 
Is shallow.
FEMALE PELVIS
(5) The pelvic outlet:
Large.
(6) The ischial 
tuberosities:
Everted. 

MALE PELVIS
(1) Pelvic inlet :
Heart shaped.
(2) The false 
pelvis:
Deep. 

MALE PELVIS
(3) The angle: 
Of the pubic arch
(50 – 60).
(4) The ischial 
spines:
Projecting
medially.

MALE PELVIS
(5) The pelvic
outlet:
Small. 
(6) The ischial
tuberosities:
Turned in. 


WALLS OF THE PELVIS
The pelvis has: 
Anterior, Posterior,
Lateral walls and an
Inferior wall (Floor).
Formed of: 
Bones and Ligaments.
Lined by: 
Muscles . 
Covered by: 
Pelvic fascia and 
Parietal peritoneum.

ANTERIOR WALL
It is the 
shallowest wall.
It is formed of 
(bones) :
The posterior 
surfaces of the
bodies of pubic
bones.
pubic rami. 
symphysis pubis.

POSTERIOR WALL
Formed of: 
Bones : sacrum & 
coccyx.
Muscle : 
Piriformis. 
Parietal pelvic fascia.

PIRIFORMIS
It is triangular in 
shape.
Origin : from 
bridges of bone
between the four
anterior sacral
foramina.
It leaves the pelvis
through the greater
sciatic foramen.

PIRIFORMIS
Insertion : upper 
border of the
greater trochanter
of the femur.
Action : lateral 
rotation of hip joint.
Nerve supply : 
sacral plexus.
LATERAL WALL
It is formed of : 
Bones : hip bones 
below the pelvic
inlet.
Ligaments : 
sacrotuberous and
sacrospinous.
Muscle : obturator 
internus and its
covering membrane.
OBTURATOR MEMBRANE
It is a fibrous sheet. 
It almost completely 
covers the obturator
foramen.
It leaves the obturator 
canal for the passage of
the obturator nerve and
vessels.
OBTURATOR INTERNUS
Origin : 
Pelvic surface of 
the obturator
membrane.
It leaves the pelvis
through the lesser
sciatic foramen.

OBTURATOR INTERNUS
Insertion : 
greater
trochanter of the
femur.
Nerve supply : 
branch from the
sacral plexus.
Action : lateral 
rotation of the
hip joint.
SACROTUBEROUS LIGAMENT
It is strong. 
Triangular in shape.
It has an extensive 
attachment between
the lateral part of the
sacrum & coccyx, the
posterior inferior iliac
spine and the ischial
tuberosity.
SACROSPINOUS LIGAMENT
It is the smaller 
ligament.
Triangular in shape.
Its apex is attached
to the ischial spine.
Its base is attached
to the lateral part
of the sacrum &
coccyx.



FUNCTION OF THE LIGAMENTS
1. They stabilize the 
sacrum on the pelvic
bones by preventing the
lower end of the sacrum
& coccyx from upward
rotation at the
sacroiliac joint by the
body weight.
2. They convert the 
greater and lesser
sciatic notches into
foramina.
INFERIOR WALL (FLOOR)
It is formed by the
pelvic diaphragm
It supports the 
pelvic viscera.

PELVIC DIAPHRAGM
It is formed by the
levator ani &
coccygeus muscles
of both sides and
their covering
fascia.
It is incomplete 
anteriorly to allow
the passage of
urethra and
vagina.

LEVATOR ANI (ORIGIN)
It is linear from : 
1. Back of body of 
pubis.
2. Tendinous arch 
from the
thickened fascia
covering
obturator
internus.
3. Ischial spine. 
PARTS
Anterior fibers: 
levator prostate or 
(sphincter vaginae).
It is inserted into the 
perineal body (A
fibrous mass in front of
anal canal).
The levator supports 
the prostate.
The Sphincter 
constricts the vagina.
Both support the 
perineal body.
PARTS
Intermediate fibers: 
(a) Pubococcygeus 
It is inserted into 
the anococcygeal
body (a small
fibrous mass
between the anus
and tip of coccyx)
PARTS
(b) Puborectalis : 
It forms a sling 
(angle) at the
Anorectal junction.
It is a mechanism to
keep the lower part
of the GIT closed.

PARTS
(c) Posterior 
fibers:
Iliococcygeus. 
Inserted into the 
anococcygeal body
and the coccyx.
ACTION OF LEVATOR ANI
1. It supports and 
maintains the
pelvic viscera in
position (especially
the uterus).
2. Forms the sling 
around the
anorectal junction.
ACTION OF LEVATOR ANI
3. Resists the rise of
the intrapelvic
pressure during
straining efforts of
the abdominal
muscles (cough &
vomiting).
4. A sphincter of the
vagina.


NERVE SUPPLY
1. Perineal 
branch (4th
sacral nerve).
2. Perineal 
branch
(pudendal
nerve)
COCCYGEUS MUSCLE
It is triangular in 
shape.
It overlies the 
sacrospinous ligament.
Origin : Ischial spine 
Insertion : Lateral 
margins of coccyx and
lower part of sacrum.
COCCYGEUS MUSCLE
Nerve supply : 
From 4th & 5th 
sacral nerves.
Action : 
Support the 
posterior part of
the pelvic floor.
PARIETAL PELVIC FASCIA
It lines the walls of the 
pelvis.
In many locations 
where it comes in
contact with bone, it
fuses with the
periosteum.
It is named according 
to the muscle it
overlies.
Obturator fascia. 
piriformis fascia. 
PARIETAL PELVIC FASCIA
Superior fascial layer of
pelvic diaphragm.
As the pelvic diaphragm
is deficient anteriorly,
the fascia becomes
continuous with the
fascia covering the
inferior surface of the
pelvic diaphragm.


VISCERAL LAYER OF PELVIC
FASCIA
It is a loose 
connective tissue
that covers and
supports all pelvic
viscera.
It fuses with the 
parietal layer when
a viscus comes into
contact with the
pelvic wall.
VISCERAL LAYER OF PELVIC
FASCIA
In some locations, it is 
thickened to form
ligaments for the
support of the viscus
(Pubovesical,
uterosacral)
They are of clinical 
importance especially in
females as they support
the uterus and prevent
its prolapse.
SACROILIAC JOINTS
They are strong 
synovial joints.
Articular surfaces :
Auricular surfaces
of the sacrum and
the iliac bones.


SACROILIAC JOINTS
Stability : 
It depends on the 
strong ligaments :
1. Posterior. 
2. interosseous 
sacroiliac ligaments.
The anterior 
ligament is thin.
SACROILIAC JOINTS
Function : 
Transmitting the weight
of the body from the
vertebral column to the
bony pelvis.

ROTATION OF THE SACRUM
The weight of the
body tends to
thrust the upper
end of the sacrum
downwards and
rotates the lower
end upwards.

ROTATION OF THE SACRUM
This is prevented by 
the following
ligaments :
Sacrospinous. 
Sacrotuberous. 
Iliolumbar : 
It is between the tip 
of the transverse
process of L5 and the
iliac crest.
SYMPHSIS PUBIS
It is a secondary 
cartilagenous joint.
The two pubic 
bones are covered
by hyaline cartilage
and connected
together by a
fibrocartilagenous
disc.
The joint allows no
movement.

SACROCOCCYGEAL JOINT
It is a cartilagenous
joint between the
bodies of the last
sacral vertebrae and
the 1st coccygeal
vertebra.
It has a great 
amount of
movement.
