2.1 Female pelvis.pptx

Pelvic bone
• Is a strong bone which forms the essential part of limb.
• It supports the weight of the upper part of the body through
the spinal column and transmits this weight to the lower limbs.
• It contains and protects the reproductive organs as well as the
bladder and rectum and allows for the passage of the fetus
during child birth.
Pelvic bones:
There are four pelvic bones
– Two innominate or hip bones
– One sacrum
– One coccyx

Innominate bones:
– Each innominate bone composed three parts: (Ilium, ischium
and pubic bone)
– Ilium: large flared out part of hip, upper border.
– Ischium: thick lower part, has large prominence
called ischial tuberosity on w/c the body rests
– Behind & little above tuberocity, an inward
projection called ischial spine.
– Station is estimated in relation to ischial spines
– Pubic bone: Forms the anterior part.
– Has body and projections: the superior ramus and
the inferior ramus.

• The two pubic bones meet at symphysis pubis and two
inferior rami forms pubic arch,
 The space enclosed by the body of the pubic bone, rami
& ischium is called obturator foramen.
 The innominate bone contains a deep cup to receive
the head of femur (thigh) called acetabulum.

The sacrum:
 Wedge shaped bone consisting of five fused vertebrae
 The upper border of the first sacral vertebra juts
forward and is known as sacral promontary.
– the prominent upper margin of the first vertebra.
– It is an important land mark in obstetrics to
measure pelvic diameters and to assess pelvic
adequacy.
 Sacral formina; four pairs of holes or through which
nerves from the cauda equine emerge to supply the
pelvic organs

The coccyx
The coccyx is a vestigial tail. It consists of four
fused vertebrae forming a small triangular
bone.
• During labour it moves backward, having
more space for the delivery of the fetus this is
called nodding.

Pelvic joint:
 There are four pelvic joints:
1. One symphysis pubis- formed at the junction of two
pubic bones.
2. Two sacro-iliac joints- the strongest joints in the
body and joins the sacrum to ilium and thus connect
the spine to the pelvis.
3. One sacro-coccygeal joint- this joint is formed
where the base of the coccyx articulate with the tip
of the sacrum.

• In the non-pregnant state there is very little
movement in these joints, but during pregnancy
endocrine activity causes the ligaments to soften,
which allows the joints to give more room for the
fetal head as it passes through the pelvis.
• The symphysis pubis may separate slightly in
later pregnancy. If it widens appreciably, the
degree of movement permitted may give rise to
pain on walking.
• The sacro-coccygeal joint permits coccyx to the
deflected backward during the birth of the head.

Pelvic ligaments:
 Each of the pelvic joints is held together by ligaments
Interpubic ligament: at the symphysis pubis
Sacro-iliac ligament
Sacrococcygeal ligament
 There are two other ligaments important in maternity
Sacrotuberous ligament
Sacrospinous ligament
 These two ligaments cross the sciatic notch and form
the posterior wall of the pelvic outlet.

 Pelvic space divided in to two:
 False Pelvis is that portion above the pelvic brim. It does not
take part in the mechanism of delivery and is of no obstetric
interest
 True pelvis determine shape and birth of birth canal
 This can be also divided in to three:
 Brim/inlet: upper margin of pubic, iliopectneal line, anterior
upper sacrum
 Cavity: pubic, ischium, ilium, and sacrum
 Outlet: pubic, ischium, ischial tuberosity, 5th sacrum

Boundaries of true pelvis;
The true pelvis has the following as its boundaries
• Superiorly it is bounded by the sacral
promonitory, linea terminalis and the upper
margin of pubic bones.
• Inferiorly it is bounded by the inferior margins of
the ischial tuberosities and the tip of the coccyx.
• Laterally it has sacroiliac notches and ligaments,
and inner surface of ischial bones
• Anteriorly by the obturator foramina and the
posterior surface of the symphysis pubis, pubic
bones and the ascending rami of ischial bones.
• Posteriorly bounded by the anterior surface of
sacrum and coccyx.

The pelvic brim:
• It is the inlet of the pelvis which divides the pelvic
cavity into false & true pelvis
• It is formed by the sacral promontory, ala of the sacrum,
arcuate line of the ilium, iliopubic eminence, pictineal
line of the pubis, pubic crest & symphesis pubis
• The plane of the brim is 55-60 ° above the horizontal
The brim is oval in shape:
– Antero-posterior diameter --- 11.25- 11.5 cm
– Transverse diameter ---- 12.5-13.5 cm

Diameter of the pelvic brim (4 types)
• Antero-posterior diameter
• Transverse diameter
• Two oblique diameters.

Measurement of pelvic diameters
Brim(inlet) Cavity(mid
pelvis)
Outlet
Anterior
posterior
diameter
11 12 13
Oblique
diameter
12 12 12
Transverse
diameter
13 12 11

The pelvic cavity
• The pelvic canal is curved , the post wall is longer
than the anterior
• It forms the curve of Carus, which the fetus has to
navigate in order to be born and has no specific
landmarks.
• The most roomy zone with almost round shape:
– Transverse diameter ---- 12.5cm
– Antero-posterior diameter --- 13.5

The pelvic outlet
 This is either an ovoid or diamond-shaped space;
 Its perimeter is partially comprised of ligaments.
 The sub-pubic arch has an angle of ---85°
 The landmarks of the pelvic outlet are as follows:
– Lower border of the symphysis pubis
– Pubic arch
– Ischial spines and ischial tuberosities
– Sacrotuberous and sacrospinous ligaments
– Lower aspect of the coccyx

Types of pelvis:
According to shape of the brim, classified in to 4
Gynaecoid pelvis(50%)
It is the normal female type ideal for delivery.
Inlet is slightly transverse oval.
Sacrum is wide with average concavity and
inclination.
Side walls are straight with blunt ischial spines.
 Sacro-sciatic notch is wide.
Subpubic angle is 90-100o.

Anthropoid pelvis (25%):
It is ape-like type.
All anteroposterior diameters are long.
All transverse diameters are short.
Sacrum is long and narrow.
Sacro-sciatic notch is wide.
Subpubic angle is narrow.

Android pelvis (20%)
It is a male type.
Inlet is triangular or heart-shaped with anterior narrow apex.
Side walls are converging (funnel pelvis) with projecting
ischial spines.
Sacro-sciatic notch is narrow.
Subpubic angle is narrow <90o.

Platypelloid pelvis (5%)
It is a flat female type.
All antero-posterior diameters are short.
All transverse diameters are long.
Sacro-sciatic notch is narrow.
Subpubic angle is wide.

Feature of the four types of pelvis
Features Gynaecoid Android Anthropoid Platypeloid
Brim Rounded Heart shaped Long oval Kidney shaped
Fore-pelvis Generous Narrow Narrowed Wide
Side-walls Straight Convergent Divergent Divergent
Ischial spines Blunt Prominent Blunt Blunt
Sciatic notch Rounded Narrow Wide Wide
Sub pubic
angle
90° <90° >90° >90°
sacrum curved curved Very slightly
curved
Very slightly
curved
Incidence 50% 20% 25% 5%

2.1 Female pelvis.pptx

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2.1 Female pelvis.pptx