Middle meningeal artery

The middle meningeal artery ("") is typically the third branch of the first portion of the maxillary artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum to supply the dura mater (the outer meningeal layer) and the calvaria. The middle meningeal artery is the largest of the three (paired) arteries that supply the meninges, the others being the anterior meningeal artery and the posterior meningeal artery.
The anterior branch of the middle meningeal artery runs beneath the pterion. It is vulnerable to injury at this point, where the skull is thin. Rupture of the artery may give rise to an epidural hematoma. In the dry cranium, the middle meningeal, which runs within the dura mater surrounding the brain, makes a deep groove in the calvarium.
The middle meningeal artery is intimately associated with the auriculotemporal nerve, which wraps around the artery making the two easily identifiable in the dissection of human cadavers and also easily damaged in surgery.
Structure.
It ascends between the sphenomandibular ligament and the lateral pterygoid muscle, and between the two roots of the auriculotemporal nerve to the foramen spinosum of the sphenoid bone, through which it enters the cranium; it then runs forward in a groove on the great wing of the sphenoid bone, and divides into two branches, anterior and posterior.
The "anterior branch", the larger, crosses the great wing of the sphenoid, reaches the groove, or canal, in the sphenoidal angle of the parietal bone, and then divides into branches that spread out between the dura mater and internal surface of the cranium, some passing upward as far as the vertex, and others backward to the occipital region.
The "posterior branch" curves backward on the squamous part of the temporal bone, and, reaching the parietal bone some distance in front of its mastoid angle, divides into branches that supply the posterior part of the dura mater and cranium.
The branches of the middle meningeal artery are distributed partly to the dura mater, but chiefly to the bones; they anastomose with the arteries of the opposite side, and with the anterior and posterior meningeal arteries. The very smallest distal branches anastomose through the skull with small arterioles from the scalp.
On entering the cranium, the middle meningeal artery gives off the following branches: 
Variation.
In approximately half of subjects it branches into an accessory meningeal artery.
Very rarely the ophthalmic artery may arise as a branch of the middle meningeal artery.
The middle meningeal artery may arise not only from the maxillary artery but also from the ophthalmic artery, or lacrimal artery.
Clinical relevance.
An injured middle meningeal artery is the most common cause of an epidural hematoma. A head injury (e.g., from a road traffic accident or sports injury) is required to rupture the artery. Emergency treatment requires decompression of the haematoma, usually by craniotomy. Subdural bleeding is usually "venous" in nature, rather than arterial.
The middle meningeal artery runs in a groove on the inside of the cranium. This can clearly be seen on a lateral skull X-ray, where it may be mistaken for a fracture of the skull. On a dry specimen, the groove is easy to see. This means that the artery is easy to study, even in specimens centuries old, and several classifications of the branches have been proposed, e.g. Adachi's classification of 1928.