Parietal Bones

The parietal bones are the paired flat bones that make up most of the roof and upper sides of the cranium. In Anatomy and Physiology I, you identify them as major bones of the skull that protect the brain and join other cranial bones at sutures.

What are the Parietal Bones?

The parietal bones are the paired bones that form much of the top and upper sides of the skull in Anatomy and Physiology I. If you picture the cranium as a protective helmet, the parietal bones make a large part of that helmet’s dome and side walls.

Each parietal bone is a flat, irregular bone, and the two bones meet at the sagittal suture along the midline of the skull. They also connect to the frontal bone at the coronal suture, the occipital bone at the lambdoid suture, and the temporal bones along the lower sides. Those sutures are immovable joints, so the skull keeps its shape while still allowing growth during development.

Because the parietal bones are part of the neurocranium, their main job is protection rather than movement. They help shield the brain from direct injury and also contribute to the skull’s overall shape. That shape matters in lab identification, because you are not just memorizing a name, you are learning how the bones fit together in a three-dimensional structure.

In infants, the parietal bones are not fully locked into place the way they are in an adult skull. They are separated by fontanels, soft spots where skull bones have not yet fused. The posterior fontanel closes as the skull matures, and the sutures become more defined.

The outer surface of the parietal bones also gives attachment points for muscles and connective tissue. The temporalis and sternocleidomastoid are two examples often mentioned in Anatomy and Physiology because the skull is not just a box for the brain. It also serves as an anchor system for movement and posture in the head and neck.

A common mistake is thinking the parietal bones are small side bones that only “fill in” space. They actually make up a major portion of the cranial vault, so when you identify them on a skull model, you are looking at one of the biggest contributors to the braincase’s protective roof.

Why the Parietal Bones matter in Anatomy and Physiology I

The parietal bones show up whenever you study how the skull is built, because they connect anatomy, development, and protection in one structure. They are a good checkpoint for whether you can move from memorizing bone names to recognizing how bones form the neurocranium.

This term also connects directly to sutures and fontanels. If you know where the parietal bones sit, you can trace the sagittal suture down the middle of the skull and the coronal suture across the front. That makes skull diagrams much easier to read, especially when a lab image asks you to identify paired bones versus single bones.

The developmental side matters too. The parietal bones help explain why infant skulls are flexible and why craniosynostosis can cause problems when sutures fuse too early. That turns a bone name into a development concept, which is exactly the kind of connection A&P expects you to make.

They also matter in muscle attachment and head shape. When you see the skull as a functional structure, the parietal bones are part of the surface that supports movement, posture, and protection at the same time.

How the Parietal Bones connect across the course

Cranium

The parietal bones are one of the major bones of the cranium, so this term sits inside the larger idea of the braincase. When you study the cranium, you are looking at the whole protective framework around the brain, and the parietal bones are a big part of its roof and sides.

Sutures

Parietal bones do not fuse into one solid plate in a living skull, they meet other bones at sutures. That matters because sutures are the landmarks you use to identify bone boundaries, skull growth, and places where premature fusion can create developmental problems.

Fontanels

Fontanels are the soft gaps between cranial bones in infants, and the parietal bones border several of them during early development. This connection helps explain why the skull can grow with the brain before the bones fully ossify and the sutures close.

Coronal Suture

The coronal suture is one of the easiest landmarks for finding the parietal bones because it runs between the frontal bone and the parietal bones. If you can locate the coronal suture on a skull image or model, you can orient yourself quickly on the anterior part of the cranium.

Are the Parietal Bones on the Anatomy and Physiology I exam?

A lab practical or skull-identification quiz may point to the large paired bones on the top and sides of a skull and ask you to name the parietal bones. You may also need to label the sagittal suture, the coronal suture, or the fontanel area in an infant skull image and explain how those features show skull growth. On written questions, you might describe why a cranial injury near the parietal region is serious, since this area helps protect the brain. If your instructor uses clinical cases, craniosynostosis is a common application because early fusion of cranial sutures changes skull shape and can affect development.

The Parietal Bones vs Temporal Bones

Parietal bones sit on the upper sides and roof of the skull, while temporal bones are lower and more lateral, near the ears. They meet along sutures, but they are not the same region, and skull diagrams often place them close enough that it is easy to mix them up.

Key things to remember about the Parietal Bones

• The parietal bones are paired flat bones that form most of the roof and upper sides of the skull.

• They belong to the cranium, so their main function is protection of the brain rather than movement.

• You can locate them by finding the sagittal suture between the two parietal bones and the coronal suture where they meet the frontal bone.

• In infants, the parietal region is part of the open, growing skull area that includes fontanels before full closure.

• Knowing the parietal bones makes skull diagrams, lab models, and developmental questions much easier to read.

Frequently asked questions about the Parietal Bones

What are the parietal bones in Anatomy and Physiology I?

They are the paired bones that form most of the roof and upper sides of the skull. In A&P, you study them as part of the cranium, where they protect the brain and meet other skull bones at sutures.

Where are the parietal bones located?

They sit on the top and upper lateral parts of the skull. If you trace the middle of the skull from front to back, the parietal bones lie on either side of the sagittal suture.

How are parietal bones different from temporal bones?

Parietal bones make up the roof and upper sides of the skull, while temporal bones are lower on the sides near the ears. A lot of students mix them up on diagrams because they touch at sutures, but their positions are different.

Why do parietal bones matter in infant skull development?

In infants, the parietal bones are part of a skull that has not fully fused yet, which allows the brain to keep growing. The soft areas and open sutures also explain why premature fusion, like in craniosynostosis, can cause skull shape changes.