Page 41 - ASOP ROT Study Guide

Note the medical meaning of the term "leg". The hip, knee and ankle joints define the ends of
these segments and allow them to move. The gastrocnemius is posterior and the tibia (crest) is
the anterior part of the leg.
The pelvic girdle (commonly known as the pelvis) consists of a large ring of bone at the base of the
backbone. It forms a firm foundation for the powerful muscles which help make the body move
forwards and upwards when we walk, run and jump. The socket side of the hip joint is a part of the
pelvic girdle.

2. THE PELVIC GIRDLE

2 . 1 Function
This is a ring of bone, joints and ligaments which:
♦ acts as the anchor for muscles which move the hip and knee joints
♦ transmits the load on the backbone to the lower limb
♦ provides a platform for the soft contents of the abdomen
♦ provides protection for important structures including the bladder and (in the female) the organs

of reproduction

2 . 2 Structure
The pelvic girdle (illustrated below) is made up of three bones: the sacrum and the two innominate
bones (innominate literally means "no name"!). The sacrum is part of the spinal column (or
backbone, or vertebral column) and is joined to each innominate bone by a fibrous joint. The two
innominate bones are joined together at the front by a cartilaginous joint, known as the
symphysis pubis, which permits a degree of "play" between the two innominate bones but
essentially holds them together.

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