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Pterion

pterion

The pterion is the H-shaped sutural junction on the lateral skull where four bones meet: the frontal, parietal, temporal (squamous), and greater wing of the sphenoid. It lies approximately 4 cm above the midpoint of the zygomatic arch and 3 cm behind the frontozygomatic suture. The middle meningeal artery runs in a groove on the inner table directly beneath the pterion.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The pterion is the thinnest and most fragile point of the skull. A direct blow here from a fist or falling object fractures through this thin bone and lacerates the middle meningeal artery running just beneath, causing acute extradural haematoma. This is the classic mechanism of the talk-and-die scenario: a brief lucid interval after the blow followed by progressive deterioration as the haematoma expands. The pterional craniotomy — the most common neurosurgical approach — centres on this landmark for access to the circle of Willis.

Pathology

Common Injuries & Conditions

Extradural Haematoma from Pterion Fracture

A direct temporal blow fractures the thin pterion and lacerates the middle meningeal artery in the epidural space; the classic lucid interval of 30-90 minutes followed by contralateral hemiparesis and ipsilateral pupil dilation indicates expanding haematoma requiring emergency pterional craniotomy and artery coagulation.