Sexual differences are related mainly
1. Heavier build and larger muscles of most men
2. Adaptation of the pelvis (particularly the lesser pelvis)
in women for parturition (childbearing).
The difference
between the male
and female pelvis
Difference
Between Male
& Female
Pelvis
41% of women
male or funnel-shaped pelvis with a
contracted outlet
long, narrow, and oval shaped
wide pelvis 2% of women
In forensic medicine (the application of medical and anatomical
knowledge for the purposes of law), identification of human
skeletal remains usually involves the diagnosis of sex.
A prime focus of attention is the pelvic girdle because sexual
differences usually are clearly visible.
Even fragments of the pelvic girdle are useful in determining
sex.
Feature Male pelvis Female pelvis
General Structure
Thick & Heavy Thin & Light
Greater pelvis
Deep Shallow
Lesser pelvis
Narrow and deep, tapering
Wide and shallow, cylindirical
Pelvic inlet Heart-shaped, narrow Oval and rounded, wide
Pelvic outlet Comparatively small Comparatively large
Ischial spines
Project further medially into the pelvic cavity
Do not project as far medially into the pelvic cavity & smooth
Feature Male pelvis Female pelvis
Obturator foramen
Round Oval
Acetabulum Large Small
Greater schiatic notch
Narrow, inverted V (approximately 70
degrees)
Almost 90 degrees
Subpubic angle
Smaller (50-60 degrees)
Larger (80-85 degrees)
Sacral promontory
Prominent Not prominent
Size of the lesser pelvis important in obstetrics
Because it is the bony canal through which the fetus passes
during a vaginal birth.
To determine the capacity of the female pelvis for childbearing,
diameters of the lesser pelvis are noted radiographically or
manually during a pelvic examination.
PELVIC DIAMETERS (CONJUGATES)
Anatomical antero-posterior diameter 11cm from tip of the coccyx to lower border of symphysis pubis
Obstetric antero-posterior diameter 13 cm from tip of the sacrum to lower border of symphysis pubis
as the coccyx moves backwards during the second stage of labour.
Diameters of pelvic outlet Antero - posterior diameters
Bituberous diameter 11 cm between inner aspects of ischial tuberosities
Bispinous diameter 10.5 cm between tips of ischial spines
Diameters of pelvic outlet Transverse diameters
Anatomical antero-posterior diameter True conjugate 11cm
from tip of sacral promontory to upper border of symphysis pubis
Diameters of pelvic inlet Antero - posterior diameters
Obstetric conjugate 10.5 cm from tip of sacral promontory to the most bulging point on back of symphysis pubis ,about 1 cm below its upper border.
shortest antero-posterior diameter
Diameters of pelvic inlet Antero - posterior diameters
Diagonal conjugate 12.5 cm 1.5 cm longer than the true conjugate From tip of sacral promontory to lower border of symphysis pubis
Diameters of pelvic inlet Antero - posterior diameters
Minimum anteroposterior (AP) diameter of the lesser pelvis
True (obstetrical) conjugate
Narrowest distance through which the baby's head
must pass in a vaginal delivery. This distance, however, cannot be measured directly during a pelvic
examination because of the presence of the bladder.
Diagonal conjugate (from inferior pubic lig. to promontory)
Measured by palpating sacral promontory with the tip of the middle finger, using the other hand to mark the level of the inferior margin of the pubic symphysis on the examining hand.
After the examining hand is withdrawn, the distance between the tip of the
index finger (1.5 cm shorter than the middle finger) and the marked level of the
pubic symphysis is measured to estimate the true conjugate, which should be
11.0 cm or greater.
Transverse diameter is the greatest distance between the linea
terminalis on either side of the pelvis.
Anteroposterior compression of the pelvis occurs during
crush accidents (as when a heavy object falls on the pelvis).
This type of trauma commonly produces fractures of the
pubic rami.
When the pelvis is compressed laterally, the acetabula and
ilia are squeezed toward each other and may be broken.
Fractures of the bony pelvic ring are almost always multiple
fractures or a fracture combined with a joint dislocation.
Pelvic fractures can result from direct trauma to the pelvic
bones, such as occurs during an automobile accident, or be
caused by forces transmitted to these bones from the lower
limbs during falls on the feet.
Weak areas of the pelvis, where fractures often occur:
Pubic rami
Acetabula
Region of the sacroiliac joints
Alae of the ilium
25 Year Old Male with displaced fracture of the sacrum and symphysis pubis. The most severe pelvic fractures separate the two sides of the pelvis from each other.
Pelvic fractures may cause injury to pelvic soft tissues, blood
vessels, nerves, and organs.
Fractures in the pubo-obturator area are relatively common and
are often complicated because of their relationship to the urinary
bladder and urethra, which may be ruptured or torn.
Sacroiliac joint dysfunction
Degenerative arthritis (osteoarthritis) Pregnancy Gout Rheumatoid arthritis Psoriasis Ankylosing spondylitis
X-ray of the sacroiliac joints showing joint space narrowing, erosive change and indistinct margins, due to sacroiliitis