Anatomy Guide › Pelvis & perineum
Coccyx
The coccyx, or tailbone, is the final segment of the spine: usually three to five small vertebrae, fused into one or two pieces, curving gently forward beneath the sacrum. It is commonly described as a vestige of the tail our distant ancestors carried, and in evolutionary terms that is true. But calling it useless is unfair to a bone that earns its keep every single day.
The coccyx is an anchor point. The gluteus maximus attaches to it, as do the muscles of the pelvic floor — the muscular hammock that supports the bladder, rectum, and reproductive organs and that contracts when you cough, lift, or laugh. Several ligaments also moor to it. Remove the coccyx and none of these structures would have their rear attachment; surgeons only excise it as a last resort for exactly this reason.
It also shares in the mundane work of sitting. When you lean back in a chair, weight shifts from the sit bones onto the coccyx. That is why a fall squarely onto the backside can bruise or fracture it, an injury called coccydynia when pain lingers — famously slow to heal because you cannot rest a bone you sit on. Cushions with a cut-out exist almost entirely for this one small bone.
In Anamo, the coccyx makes a precise, low-midline target. It touches the sacrum directly and sits among the pelvic-floor muscles, so a hot guess here narrows the field to a small, learnable neighborhood — one where knowing your attachments pays off.
- Made of three to five small fused vertebrae below the sacrum
- Anchors the gluteus maximus and the pelvic-floor muscles
- Bears part of your body weight whenever you lean back while sitting
- Injury to it (coccydynia) is notoriously slow to heal
Think you could find the coccyx on a 3D model? Play Anamo and test yourself — every guess is color-coded by how close it lands to the mystery structure.