Coccyx

What it means

The coccyx is the medical name for the tailbone — the small, triangular structure at the very bottom of the spine, sitting just below the sacrum. It is made of three to five tiny bones that are usually fused together, the remnant of what would be a tail in other animals. Several muscles and ligaments of the pelvic floor attach to it, and it helps you bear weight when you sit and lean back.

Why it appears on a CT, MRI or X-ray report

Radiologists describe the coccyx when checking its shape, angle, and alignment, and when looking for fractures or dislocation after a fall onto the bottom or a hard landing. They note whether it curves normally or is angled in a way that might cause pain, and any spots within the bone. Naming the coccyx simply points to the very lowest part of the spine, right at the tip.

What it usually means

Most reports name the coccyx simply to set the location of a finding, and the word on its own carries no alarm. Reassuring phrases include intact and normal alignment. The most common reason it comes up is pain after a fall onto the buttocks, sometimes from a bruise, fracture, or partial dislocation; this condition, called coccydynia, is uncomfortable but usually settles over weeks to months with cushioned seating, pain relief, and time rather than surgery. Reports may also note a naturally angled or curved tailbone, which is a normal variation. The descriptors that warrant attention are fracture, dislocation, or a lesion within the bone. As with any bone, the name is just an address; the meaning lives in the descriptor beside it and how it matches your symptoms.

When to follow up

The name alone needs no action. Ask your doctor about any descriptor attached to it. Tailbone pain after a fall is usually managed with a cushion, pain relief, and patience, even when there is a small fracture. Seek prompt care if pain is severe and not improving, or if you develop new numbness around the buttocks or groin, leg weakness, or any change in bladder or bowel control.

A plain-language way to picture it

Picture the small, pointed tip at the bottom of a curved walking stick — the last little segment right at the end. Your tailbone is that final tip of the spine. You become very aware of it if you slip and land hard on your bottom, because it takes the impact directly, which is exactly when it tends to show up on a report.