Parietal bone

Bone forming part of the skull

The parietal bone is a paired, flat bone located on the lateral sides of the skull. It forms a significant portion of the cranial vault, which encases and protects the brain.

Anatomy

The parietal bones are situated between the frontal bone anteriorly and the occipital bone posteriorly. They are bordered inferiorly by the temporal bone and the sphenoid bone. Each parietal bone is roughly quadrilateral in shape and has two surfaces, four borders, and four angles.

Surfaces

The external surface of the parietal bone is convex and smooth, providing attachment for the temporalis muscle. The internal surface is concave and contains grooves for the middle meningeal artery and venous sinuses.

Borders

• Sagittal border: The superior border, which articulates with the opposite parietal bone at the sagittal suture.
• Squamous border: The inferior border, which articulates with the temporal bone.
• Frontal border: The anterior border, which articulates with the frontal bone at the coronal suture.
• Occipital border: The posterior border, which articulates with the occipital bone at the lambdoid suture.

Angles

• Frontal angle: Located at the junction of the coronal and sagittal sutures.
• Sphenoidal angle: Located at the junction of the coronal and squamous sutures.
• Occipital angle: Located at the junction of the sagittal and lambdoid sutures.
• Mastoid angle: Located at the junction of the lambdoid and squamous sutures.

Development

The parietal bone develops from two primary ossification centers that appear in the membrane covering the developing brain. These centers appear around the eighth week of fetal development and fuse to form a single bone by birth. The bone continues to grow and remodel throughout childhood and adolescence.

Function

The primary function of the parietal bone is to protect the brain by forming part of the cranial vault. It also provides attachment points for muscles involved in mastication and head movement.

Clinical significance

Fractures of the parietal bone can occur due to trauma and may lead to complications such as epidural hematoma if the middle meningeal artery is damaged. Surgical interventions may be necessary in severe cases.

Images

File:Parietal bone lateral view.png

Lateral view of the parietal bone (highlighted in green).

File:Parietal bone internal view.png

Internal view of the parietal bone showing grooves for the middle meningeal artery.

Related pages

• Skull
• Cranial sutures
• Frontal bone
• Occipital bone
• Temporal bone