- 1° function of pelvic girdle is to allow movement of body, especially walking and running.
- It permits the person to sit or kneel.
- Woman’s pelvis is adapted for childbearing and because of its increased width and rounded brim , women are less speady than man.
- Pelvis transmit the weigh of the trunk to the legs acting as bridge between the femur.
- Pelvis takes the weight of the sitting body on ischial tuberosity.
Pelvic bone –
There are 4 bones :
(1) 2 INNOMINATE [NAMELESS] HIP BONE:- Each bone composed of 3 parts:-
THE ILIUM:– It is the large flared- out part when the hand is placed on the hip it rest on the iliac crest , which is the upper border. At the front of iliac crest a bony prominence known as anterior superior iliac spine, a short distance below it is anterior inferior iliac spine 2 similar point at the other end of iliac crest, namely posterior superior, posterior inferior iliac spine. The concave anterior Surface of ilium is iliac fossa.
THE ISCHIUM:– It is thick lower part. It has large prominence known as ischial tuberosity on which the body rest when sitting behind & little above the tuberosity is an inward projection, ischial spine.
PUBIC BONE:– Bone forms the anterior part. It has body or 2 oar like projection- superior ramus & inferior ramus. The 2 public bone meet at symphysis pubis & 2 inferior rami form public arch, the space enclosed by body of public bone, rami & ischium called obturator foramen.
Hip bone contain a deep cut to receive the head of femur. This is termed as acetabulum. On lower border 2 curves are formed. One extends from posterior inferior iliac spine called greater sciatic notch, other lies between the ischial spine & ischial tuberosity is lesser sciatic notch.
(2)THE SACRUM –
It is a wedge shaped bone consisting of five fused vertebra. Upper border of the 1st sacral vertebra just forwards, is sacral promontory. The anterior surface of sacrum is concave referred as hollow of sacrum. Laterally extends into sacral ala or wing. 4 pair of holes or foramina pierce the sacrum through these nerves from cauda equina emerges to pelvis organ. Posterior surface is rough to receive attachment of muscles.
(3.)THE COCCYX –
Is a vestigial tail,consist of 4 fused vertebra, forming a small triangular bone.
Pelvic Joints :-
There are 4 pelvic joints –
- One symphsis pubis – Is formed at the junction of 2 pubic bones, which are united by a pad of cartilage.
- Two sacroiliac joint – These are strongest joint in the body. They join the sacrum to the ilium and connect spine to pelvis.
- Sacrococcygeal joint – This joint is formed where the base of coccyx articulate with tip of the sacrum.
In non pregnant state there is a very little movement in these joints but during pregnancy endocrinal activity cause the ligament to soften, may provide more room for the fetal head as it passes through pelvis.
Pelvic Ligament :-
Each of the pelvic joint is held together by ligament.
- Interpubic ligament at symphysis pubis
- Sacroiliac ligament.
- Sacrococcygeal ligament.
And the other 2 ligaments are –
- Sacrotuberous ligament runs from the sacrum to the ischial tuberosity.
- Sacrospinous ligament from sacrum to ischial spine.