Pterion
Encyclopedia
The pterion is the point corresponding with the posterior end of the sphenoparietal suture
Sphenoparietal suture
The Sphenoparietal suture is the cranial suture between the sphenoid bone and the parietal bone....

.

Location

It is situated about 3 cm. behind, and a little above the level of the zygomatic process
Zygomatic process of frontal bone
The zygomatic process of frontal bone is the part of the zygomatic process consisting of the frontal bone.The supraorbital margin of the frontal bone ends laterally in the zygomatic process, which is strong and prominent, and articulates with the zygomatic bone...

 of the temporal bone
Temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...

.

It marks the junction between four bones:
  • the parietal bone
    Parietal bone
    The parietal bones are bones in the human skull which, when joined together, form the sides and roof of the cranium. Each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin pariet-, wall....

  • the squamous part of temporal bone
  • the greater wing of sphenoid bone
  • the frontal bone
    Frontal bone
    The frontal bone is a bone in the human skull that resembles a cockleshell in form, and consists of two portions:* a vertical portion, the squama frontalis, corresponding with the region of the forehead....


Clinical significance

The pterion is known as the weakest part of the skull.

Clinically, the pterion is relevant because the anterior division of the middle meningeal artery
Middle meningeal artery
The middle meningeal artery is typically the third branch of the first part of the maxillary artery, one of the two terminal branches of the external carotid artery...

 runs beneath it, on the inner side of the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...

, which is quite thin at this point. The combination of both a vital artery in this area and the relatively thin bone structure has lent itself to the name "God's little joke" by some physicians.

A blow to the pterion (e.g. in boxing
Boxing
Boxing, also called pugilism, is a combat sport in which two people fight each other using their fists. Boxing is supervised by a referee over a series of between one to three minute intervals called rounds...

) may rupture the artery causing an epidural haematoma. The pterion may also be fractured indirectly. Blows to the top or back of the head may not cause fracture at the site of impact, but may place sufficient force on the skull that its weakest part, the pterion, will fracture.

Etymology

The pterion receives its name from the Greek root pteron, meaning "wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

".

In Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

, Hermes
Hermes
Hermes is the great messenger of the gods in Greek mythology and a guide to the Underworld. Hermes was born on Mount Kyllini in Arcadia. An Olympian god, he is also the patron of boundaries and of the travelers who cross them, of shepherds and cowherds, of the cunning of thieves, of orators and...

, messenger of the gods, was enabled to fly by winged sandals, and wings on his head, which were attached at the pterion.

External links

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