The structure indicated is known as pterion.

Pterion is the name given to the region on the lateral aspect of the skull where four bones are joined:

• Parietal bone
• Squamous part of temporal bone
• Front bone
• Greater wing of sphenoid bone

Pterion is a point of clinical significance – the skull is very thin at this point. In addition to being structurally weak due to being the point of union between several bones, it also lies over the anterior division of the middle meningeal artery. Fracture of the skull at this point can therefore disrupt the middle meningeal artery, leading to an extradural (epidural) haematoma.

Pterion involves three cranial sutures:

• Sphenoparietal suture
• Coronal suture
• Squamous suture

Learn all about the sutures of the skull in this tutorial.