You’ve probably touched them a thousand times today without even realizing it. Reach up. Feel the top and sides of your head. That hard, curved expanse under your hair isn't just one solid bucket for your brain. It’s a pair of plates. These are the parietal bones. If you're asking where are the parietal bones located, the simplest answer is that they form the bulk of the "roof" and the sides of your skull.
They are massive. In the world of cranial anatomy, they are the heavy lifters of protection. While the frontal bone gets all the glory for being your forehead and the occipital bone guards the back, the parietal bones do the grueling work of covering the parietal lobes of the brain. They meet right in the middle of your scalp, creating a seam that looks like a jagged mountain range on a map.
The Precise Neighborhood of the Parietal Bones
To get technical—but not too boring—the parietal bones sit between the frontal bone (front) and the occipital bone (back). They are quadrilateral in shape. Imagine two slightly curved, rectangular shields.
These shields are joined at the very top of your head by the sagittal suture. This is that long line you can sometimes feel if you run your finger from the bridge of your nose straight back toward the nape of your neck. It’s where the left and right parietal bones lock together like a permanent 3D puzzle.
They don't just sit there. They interface with almost every other major player in the skull.
- Up front, they hit the frontal bone at the coronal suture.
- At the back, they meet the occipital bone at the lambdoid suture, named because it looks like the Greek letter lambda.
- On the sides? They overlap with the temporal bones (where your ears are) and a bit of the sphenoid bone.
It’s a tight fit. It has to be. Your brain is essentially a high-end computer floating in a jar of saltwater, and the parietal bones are the armored casing. Without them, the most sensitive parts of your sensory processing center would be wide open to every bump and bruise of daily life.
Why Your "Soft Spot" Was Actually These Bones Waiting to Grow
When you were a baby, your parietal bones weren't actually touching. This is the part people find kinda creepy but also fascinating.
Infants have "fontanelles." You know them as soft spots. Because a baby’s brain grows at a terrifyingly fast rate, the skull bones need room to expand. Also, let’s be real: a rigid, fully fused skull wouldn't make it through the birth canal very easily. The parietal bones are central to this. The large soft spot on top of a baby’s head—the anterior fontanelle—is the gap where the parietal bones and the frontal bone haven't met yet.
Eventually, usually by age two, these gaps close. The bones knit together through a process called intramembranous ossification. They don't just "touch"; they create fibrous joints called sutures. As you age, these sutures get even tighter. In some elderly people, the sutures almost disappear as the bones fuse into what looks like a single unit.
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The Inside is Just as Busy as the Outside
If you were to pop a parietal bone off and look at the underside (please don't), you wouldn't see a smooth surface. It’s covered in grooves. These aren't accidents.
The inner surface of the parietal bone is etched with channels for the middle meningeal artery. Think of it like a custom-molded tray. The bone grows around the blood vessels to protect them. This is a brilliant bit of biological engineering, but it’s also a vulnerability. If you take a hard hit to the side of the head—specifically near the pterion, where the parietal, frontal, temporal, and sphenoid bones all meet—that artery can rupture. Because the bone is so hard, the blood has nowhere to go. This causes an epidural hematoma, a medical emergency that neurologists like Dr. Aaron Cohen-Gadol often highlight as a critical reason for wearing helmets.
Mapping the Landmarks: More Than Just a Flat Surface
The parietal bone has four borders and four angles. It sounds like a geometry class, but it's actually just a way for surgeons to navigate.
- The Parietal Eminence: This is the "peak" of the curve. If you have a "square" head, your eminences are likely more pronounced. It’s often the first place the bone starts to harden in the womb.
- Temporal Lines: There are two faint ridges arching across the bone. These aren't for show; they are attachment points for the temporal muscle. Every time you chew a steak, your parietal bones are helping anchor the muscles doing the work.
- Parietal Foramen: Most people have a tiny hole near the back of the sagittal suture. It’s small. A tiny vein (the emissary vein) passes through here. It’s basically a pressure release valve for the blood system inside your head.
What Happens When Things Go Wrong?
Because we now know where are the parietal bones located, we can understand the specific risks associated with them.
Fractures are the big one. Linear fractures—cracks that don't move the bone—are common in falls. They usually heal on their own because the parietal bone has a decent blood supply. However, depressed fractures are nastier. This is where the "shield" gets pushed inward toward the brain.
Then there’s Paget’s disease. This is a condition where the body’s bone-recycling process goes haywire. The parietal bones can become thickened and brittle. Patients often notice their hats don't fit anymore. It’s a strange, slow-motion expansion of the skull that can lead to headaches or hearing loss if the bone starts pressing on nerves.
Misconceptions: It's Not Just "The Top"
A common mistake is thinking the parietal bone is just the flat part on top. It’s not. It curves significantly down the sides. If you wear glasses, the arms of the frames are likely resting right over the lower edge of your parietal bones.
Another weird fact? The parietal bone is actually composed of two layers of "compact" bone with a "spongy" layer in the middle called the diplöe. This sandwich structure is what makes it so strong. It absorbs shock. If your skull were just one solid, brittle layer, it would shatter like a porcelain plate. Instead, it acts more like high-tech laminate.
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Take Care of Your Parietal Plates
Honestly, we take these bones for granted. They aren't joints we have to ice like knees, and they don't break as often as ribs. But they are the primary gatekeepers for the parietal lobe, which handles everything from your sense of touch to how you understand spatial navigation.
If you're feeling adventurous, try to find your own sagittal suture. Wash your hands, sit in a quiet room, and slowly walk your fingers from your forehead back. You’ll feel a slight ridge or a change in the "give" of the scalp. That’s the junction. That’s where your two parietal bones have spent the last few decades protecting everything that makes you you.
Actionable Next Steps for Bone Health
- Check your helmet fit: If you cycle or skate, ensure the helmet covers the "eminences"—the widest part of your head. If the helmet sits too far back, your parietal-frontal junction is exposed.
- Monitor "New" Headaches: Pain specifically localized to the suture lines can sometimes indicate tension or, rarely, issues with intracranial pressure.
- Calcium and Vitamin D: Standard, but true. The diplöe (spongy layer) of the skull remains metabolically active throughout your life. Keep it fueled.
- Palpate for irregularities: Most lumps on the skull are harmless (like pilar cysts), but knowing the "topography" of your parietal bones helps you spot changes early.