Sphenoidal fontanelle

The sphenoid fontanelles (a.k.a. anterolateral fontanelle) are a set of paired fontanelles situated on each side of the skull, where the sphenoid (greater wing), parietal, temporal (squamous part), and frontal bones join together.

Around six months after birth, the sphenoid fontanelles close, and in adults, the area where these four bones meet is known as the pterion. This particular region of the skull is highly delicate, and a forceful impact on the lateral side of the head can easily result in a fracture. This fracture can cause the middle meningeal artery, which is positioned beneath the pterion area within the cranial cavity, to rupture. The rupture of this artery can lead to a life-threatening condition called epidural or extradural hematoma. Such a situation can result in elevated pressure within the skull, brain herniation, and ultimately, death. Immediate evacuation of the blood is necessary as soon as this neurosurgical emergency is identified.