key term - Sacrum

Definition

The sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. It consists of five fused vertebrae which are merged together during adulthood to support the weight of the upper body when sitting and standing.

Related terms

Coccyx:

The coccyx, or tailbone, is a small bone located at the very bottom of the spinal column, directly below the sacrum, formed by four fused vertebrae.

Lumbar Spine: The lumbar spine is comprised of five vertebrae in the lower back area and sits directly above the sacrum, supporting much of the body's weight and enabling flexible movement.

Pelvic Girdle: The pelvic girdle is made up of two hip bones that connect to each other at the front and to the sacrum at the back, forming a ring-like structure that supports leg movements and balances body weight