Pterion

The pterion is the H-shaped formation of sutures on the side of the calvarium representing the junction of four skull bones:

• the greater wing of the sphenoid bone
• squamous portion of the temporal bone
• frontal bone
• parietal bone

It is located at the anterior end of the squamous suture, whereas the asterion is located at the posterior end. It is one of the skull landmarks, craniometric points for radiological or anthropological skull measurement.

Variant anatomy

• only two or three of the bones may meet
• all four bones meet at a single point

Related pathology

Clinically it is located two fingers’ breadth superior to the zygomatic arch and a thumb’s breadth posterior to the frontal process of the zygomatic bone .

The pterion overlies the course of the anterior division of the middle meningeal artery. Hence fractures in the region may injury the artery and cause extradural hemorrhage.

In neurosurgery, the pterional craniotomy is a common approach to the middle cranial fossa.