The bone sticking out of the back of your head is most commonly an exaggerated external occipital protuberance (EOP). This is a normal anatomical variation of the occipital bone, which forms the lower back part of your skull.
Understanding the External Occipital Protuberance (EOP)
The EOP is a prominent bump or ridge located at the base of the skull, where the neck muscles attach. While present in everyone to some degree, its size can vary significantly from person to person. When it is particularly pronounced, it can be quite noticeable to the touch or even visible.
Here's a breakdown of common terms used to describe this bony prominence:
- Occipital Spur: A specific term often used to describe a very pronounced, pointed EOP.
- Occipital Knob: Another common term referring to a rounded, prominent EOP.
- Occipital Bun: This term often describes a broader, more rounded bulge at the back of the head.
- Chignon: A term with historical and anthropological roots, sometimes used to describe a prominent EOP.
- Inion Hook: Yet another anatomical descriptor for this specific feature.
Term | Description |
---|---|
Occipital Spur | A distinct, often pointed, bony projection. |
Occipital Knob | A rounded, noticeable bump. |
Occipital Bun | A broader, more diffuse bulge. |
Chignon / Inion Hook | Alternative terms for a prominent external occipital protuberance. |
Is It Normal?
Despite its noticeable presence, an exaggerated external occipital protuberance is considered a normal variant in medical literature. It's not typically a cause for concern unless it's accompanied by pain or other symptoms.
Historically, prominent EOPs have been a topic of discussion in anthropological literature, sometimes associated with traits observed in Neanderthals. However, from a medical standpoint, its presence is simply a variation in human anatomy, much like differences in nose shape or ear size. While it might be a cosmetic concern for some, it rarely indicates an underlying medical problem.
It's important to differentiate a normal bony prominence from other conditions that might cause lumps on the head, such as cysts or tumors. However, if the lump feels hard and is clearly part of the bone structure at the typical location of the EOP, it is most likely this common anatomical feature.