häntäluusta

Häntäluusta, also known as the coccyx, is a small triangular bone located at the very base of the vertebral column in humans and some primates. It consists of three to five fused vertebrae and serves as the vestigial remnant of a tail, reflecting evolutionary ancestry.

The coccyx is attached to the sacrum at the sacrococcygeal symphysis, a slightly movable joint that allows limited flexibility. It acts as an attachment point for various muscles, ligaments, and tendons, including those involved in sustaining sitting posture, supporting pelvic organs, and controlling bowel movements.

Anatomically, the coccyx varies in size and shape among individuals. Its structure includes a base, which articulates with the sacrum, and a apex, pointing downward. The anterior surface is smooth, while the posterior surface may have rudimentary spinous processes and foramina.

Injury to the coccyx, such as fractures or dislocations, often results from falls or direct trauma. Such injuries can cause pain, particularly when sitting or during certain movements, a condition known as coccydynia. Treatment typically involves pain management, physical therapy, and in severe cases, surgical removal.

The coccyx plays a minor but important role in human anatomy. Despite its reduced function compared to other vertebral bones, it contributes to pelvic stability and weight distribution during sitting and movement. Its evolutionary significance reflects the transition from tail-bearing ancestors to modern humans.