Diameters
Brim:
Antero posterior:
Anatomical conjugate/true
conjugate/conjuagate vera: It is the distance between the mid point of the sacral
promontory to the inner margin of the upper border of symphysis pubis. It
measures 11 cm.
Obstetric conjugate: it is the distance between
the midpoint of sacral promontory to prominent
bony projection in the midline on the inner surface of the
symphysis-pubis. It measures 10 cm
Diagonal conjugate: it is the distance between
the lower border of symphysis pubis to the midpoint of sacral promontory. It
measures 12 cm
Transverse diameter: It is the distance between
the two farthest points on the pelvic brim over the ilio pectineal lines. It
measures 13 cm
Oblique diameters:
There are two oblique diameters-
right and left. Each one extends from one sacro iliac joint to the opposite
ilio pubic eminence and measures about 12 cm. (right or left denotes
the sacro iliac joint from which it
starts)
Cavity:
Cavity is the segment of the
pelvis bounded by the inlet and below by plane of least pelvic dimensions.
Diameters:
Antero- posterior: It measures from the midpoint
of the posterior surface of the symphysis pubis
to the junction of 2nd
or 3rd sacral vertebrae. It
measures about 12 cm
Transverse/ oblique
diameter:
It cannot be precisely
measured as the points lie over the soft tissues covering the sacro sciatic
notches and obturator foramina.
Outlet:
Obstetrical outlet : It is the segment of pelvis
bounded above by the plane of least pelvic dimensions and below by the
anatomical outlet.
Transverse: (Bispinous) it is the
distance between the tip of two ischial spines. It measures
10.5 cm
Antero posterior: It extends from the
inferior border of the symphysis pubis to the tip of sacrum. It measures 11 cm.
Posterior sagital: it is the distance between
the tip of the sacrum and midpoint of the bispinous diameter,
5 cm.
Anatomical outlet : Known as bony outlet.. It is
bounded in front by the lower border of the symphysis pubis; laterally by the
ischiopubic rami, ischial tuberositv and sacro spinous ligament and posteriorly
by the tip of coccyx.
It is diamond shaped
Antero posterior diameter: extends from the lower
border of symphysis pubis to the tip of coccyx. It measure 13 cm
Transverse ( inter tuberous ) :
It measure between the inner borders of ischial tuberosities. It is 11 cm .
Oblique diameter : it is said to be between
the obturator foramen and the sacro spinous ligament. It is 12cm
|
|
Anterior
–Posterior
(in cms)
|
Oblique
(in cms)
|
Trsnsverse
(in cms)
|
|
Inlet (brim)
|
11
|
12
|
13
|
|
Cavity
|
12
|
12
|
12
|
|
Outlet
|
13
|
12
|
11
|
Types of pelvis:
The gynaecoid pelvis
The android pelvis
The anthropoid pelvis
The platypelloid pelvis
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