3. Learning tasks
At the end of this session students will be able
to:
• Describe the anatomy and physiology of the
female bony pelvis
• Differentiate pelvic bones, pelvic joints and
pelvic ligaments
• Describe pelvic diameters related to fetal skull
• Identify types of pelvis
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4. Anatomy and Physiology of the
Female Bony Pelvis
Definition
Bony pelvis is a basin like structure which
connects the spine to the lower limbs.
It provide protection and contains the female
reproductive organs and other pelvic organs.
The reproductive organs are:
The vagina
The uterus
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5. • The fallopian tubes
• The ovaries
The other pelvic organs contained in the
pelvis include the :
• The bladder
• The urethra
• Pelvic colon
• Rectum and anal canal
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6. • The female pelvis is the bone compartment
which supports the vertebrae column and
articulates with the lower limbs, it permits a
person to sit and kneel.
• It forms a bonny passage through which the
fetus passes during labour.
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7. It comprises of four bones
• Two in nominate bones( The hip bone)
• One sacrum
• One coccyx
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9. The innominate bone
• Is made up of three bones: Illium, Ischium and the
Pubis
The illium
• Is the large flared-out part; when the hand is placed
on the hip it rests on the iliac crest, which is the
upper border. At the front of the iliac crest can be felt
a bony prominence known as the anterior superior
iliac spine.
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10. • Below is the anterior inferior iliac spine. There
are two similar points at the other end of the
crest, posterior superior and posterior inferior
iliac spines.
The ischium
• Is the thick lower part which has a large
prominence known as the ischial tuberosity,
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11. • on which the body rests when sitting. Behind
and a little above the tuberosity is an inward
projection known as, the ischial spine. During
labor the station of the fetal head is estimated
In relation to the ischial spines.
The pubic bone
• This bone forms the anterior part.
• It has a body and two oar-like projections, the
superior ramus and the inferior ramus.
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12. • The two pubic bones meet at the symphysis pubis
and the two inferior rami form the pubic arch,
merging into a similar ramus on the ischium.
• The space enclosed by the body of the pubic bone,
the rami and the ischium is called the obturator
foramen.
• The innominate bone contains a deep cup to receive
the head of femur, called acetabulum.
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13. • On the lower boarder of the innominate bone are
found two curves.
• One extends from the posterior inferior iliac spine up
to the ischial spine and is called greater sciatic notch.
• The other lies between the ischial spine and ischial
tuberosity is the lesser sciatic notch.
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14. The sacrum
• The sacrum is a wedge-shaped bone consisting of
five fused vertebrae.
• The upper border of the first sacral vertebra juts
forward and is known as sacral promontory.
• The anterior surface of the sacrum is concave and is
referred to as the hollow of the sacrum.
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15. • Laterally the sacrum extends into a wing or ala.
• Five pairs of holes or foramina pierce the sacrum
and, through these, nerves emerge to supply the
pelvic organs.
• The posterior surface is roughened to receive
attachment of muscles
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16. The coccyx
• Is a vestigial tail which consist of four fussed
vertebral forming a small triangular bone. The
coccyx articulates with the fifth sacral vertebra
to form the sacrococcygeal joint. During birth
the coccyx is usually forced backwards to
allow more room for the fetus to pass.
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19. • A joint is the part of the body where two or
more bones meet to allow movement.
• Every bone in the body except for the
hyoid bone in the throat meets up with at
least one other bone at a joint.
• The shape of a joint depends on its
function. A joint is also known as an
articulation.
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20. Pelvic joints
There are four pelvic joints;
• One symphisis pubis
• Two sacro iliac joints
• One sacrococcygeal joint.
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21. The pelvic joints are not very mobile in non
pregnant woman, but during pregnancy the
endocrine activity causes the ligaments of the
joints to soften which allows the joints to soften
and stretch during labour.
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22. The symphisis pubis
• It is formed at the junction of the two pubic
bones, which are united by a pad of cartilage.
• It widens during the last months of
pregnancy and, because of its increased
mobility may cause the pregnant woman pain
as she walks.
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23. Sacro-iliac joints
• These are the strongest joint in the body.
• They join the sacrum to the ilium and thus
connect the spine to the pelvis.
• During pregnancy much stress is placed on
these joints and multipara often complain of
backache during pregnancy and for few weeks
following delivery.
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24. Sacrococcygeal joint
• This joint is formed where the base of the
coccyx articulates with the tip of the sacrum.
• The joint allows the coccyx to move
backwards during birth, thus widening the
outlet of the pelvis.
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27. • Ligaments often connect two bones
together, particularly in the joints
• Like strong, firmly attached straps or
ropes, they stabilize the joint or hold the
ends of two bones together.
• This ensures that the bones in the joint
don't twist too much or move too far apart
and become dislocated.
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28. Each of the pelvic joints is held together by
ligaments;
• the ligaments binding the sacrum
and ileum at the sacral-iliac joint are the
strongest in the whole body.
• The pelvis is bounded by three pairs of strong
ligaments .
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29. • The ligaments are named according to the
bones they bind.
1. Interpubic ligaments at the symphysis pubis
2. Sacroiliac ligament,
3. Sacrococcygeal ligaments.
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30. There are other two ligaments important in
midwifery
1. Sacrotuberous ligaments - from the sacrum
to the ischial tuberosity
2. Sacrospinous ligament - from the sacrum to
the ischial spine.
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34. • Pelvic floor is a group of muscles found in
the floor (the base) of the pelvis (the
bottom of the torso).
• If you think of the pelvis as being the home
to organs like the bladder, uterus or
prostate, and rectum, the pelvic floor
muscles are the home's foundation.
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36. • The pelvic floor muscles are located
between the tailbone (coccyx) and the
pubic bone within the pelvis.
• They support the bowel and bladder (as
well as the uterus and vagina in females).
• Muscular bands (sphincters) encircle the
urethra, vagina and anus as they pass
through the pelvic floor
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37. • The pelvic floor is formed by the soft tissues
that fill the outlet of the pelvis
• The most important of these is the strong
diaphragm of muscle slung like a hammock
from the walls of the pelvis.
• Through it pass the urethra, the vagina and
the anal canal
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38. Functions
• The pelvic floor supports the weight of the
abdominal and pelvic organs.
• Its muscles are responsible for the voluntary control
of micturation and defecation and play an important
role in sexual intercourse
• It provides the outlet to the reproductive tract, the
vagina and introitus
• During child birth it allows the passive movements of
the fetus through the birth canal and
• It relaxes to allow the exit of the foetus from the
pelvis
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40. Superficial layers
The superficial layer which is composed of five
muscles;
• The external anal sphincter encircles the anus
and is attached behind by a few fibers to the
coccyx.
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41. • The transverse perineal muscles pass from
the ischial tuberosity to the centre of the
perineum.
• The bulbocavernosus muscles pass from the
perineum forward around the vagina to the
corpora cavernosa of the clitoris just under
the pubic arch.
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42. • The ischial cavernosus muscles pass from the
ischial tuberosities along the pubic arch to the
corpora cavernosa.
• The membranous sphincter of the urethra is
composed of muscle fibres passing above and
below the urethra and attached to the pubic
bone.
• It is not a true sphincter since it is not circular
but it acts to close the urethral
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44. The deep layer
• This layer is composed of three pairs of
muscles which together are known as levator
ani muscles.
• Each levator ani muscle (left and right) consist
of the following:
o The pubococcygeus muscle from the pubis to
the coccyx, with a few fibres crossing over in
the perineal body to form its deepest part
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45. o The iliococcygeus muscle passes from the
fascia covering the obturator internus muscle (
the white line of the pelvic fascial) to the
coccyx
o The ischiococcygeus muscle from the ischial
spine to the coccyx, in front of the
sacrospinous ligaments
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48. The Perineal Body
• This is a pyramid of muscle and fibrous tissue
situated between the vagina and the rectum.
• It is made up of fibers from the muscles
described above.
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49. • The apex, which is the deepest part is formed
from the fibers of the pubococcygeus muscle
which cross over at this point;
• the base is formed from the transverse
perineal muscles, which meet in the
perineum, together with the bulbocavernosus
in front and the external anal sphincter
behind.
• The perineal body measures 4cm in each
direction.
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50. Key message
• The Relaxation of Pelvic Floor Muscles can
Lead to Stress Incontinence and Prolapse of
The Uterus, Bladder and Bowel After
Childbirth
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51. Key Points
• The female pelvis forms a bony canal through
which the fetus passes during labour.
• The midwife must be competent to recognize
a normal pelvis, in order to be able to detect
deviations from normal and refer to the
doctor.
• There are 4 bones of the pelvis two
innominate bones, sacrum and coccyx
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52. • The sacro-iliac joints are the strongest joints in
the body
• During pregnancy the pelvic joints becomes
slightly mobile than in non pregnant due to
the effects of the hormones relaxin.
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53. • The pelvic floor is made up of soft tissues
which fills the pelvic floor, the superficial layer
consisting of five muscles and the deep layer
consisting of lavetor ani muscles
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54. Activity- Group presentation
• Describe and demonstrate different exercises
needed to keep the pelvic floor muscles strong
during and after pregnancy. Group 7
Note:
Presentation date:
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55. References
• Fraser, D, M. & Cooper, M. A. (2003) Myles
Textbook for midwives (14th Ed.) Churchill
Livingstone.
• Fraser, D, M. & Cooper, M. A. (2009) Myles
Textbook for midwives (15th Ed.) Churchill
Livingstone.
• Fraser, D. M; Cooper, M. A. & Nolte, A. G.
(2006) Myles Textbook for Midwives (African
Ed.) Churchill Livingstone.
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56. • Fraser, D. M; Cooper, M. A. & Nolte, A. G.
(2010) Myles Textbook for Midwives (African
Ed.) Churchill Livingstone
• Lavine C. Women to women (2011, April 19)
Pelvic floor. Retrieved from
http://www.womentowomen.com/urinaryinc
ontinence/pelvicfloorhealth.aspx
• London, Marcia L et el (2007) Maternal and
child nursing care, 2nd ed. Pearson, London.
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57. • Pilliteri, Adele (2003) Maternal and child
health nursing: care of the childbearing and
childrearing family, 4th ed. Lippincott, London.
• Tiran, D. (2003) Baillier’s Midwives Dictionary
(10th ed) Bailliere Tindall
• Vagina: Description. Retrieved from
http://lucy.stanford.edu/vagina2.html
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59. Evaluation
• Explain the bones of the pelvis
• Explain the pelvic joints and ligaments
• Explain the three pairs of muscles known as
lavetor ani muscles
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