The Anatomy of the Middle Meningeal Artery

One of two terminal branches of the internal carotid artery, the middle meningeal artery is a major source of blood for the brain and cranium. It arises behind the condylar process of the mandible, or jawbone, and passes through the foramen spinosium, an opening in the back of the skull. From there, its branches supply the meninges, the three protective layers that surround the brain, as well as the calvaria or skull cap.

Since it serves such an important function, disorders or injury to this artery can be very dangerous, leading to conditions such as epidural hematoma (a pooling of blood between the skull and the membrane that covers the brain, called the dura mater) and aneurysm (ballooning of the artery), as well as migraine headache and others.

The middle meningeal artery arises at the intracranial fossa—a cavity on the side of the cranium—where it branches off from the maxillary artery which is connected to the external carotid artery, an important source of blood to the brain.

From there it moves upwards and accesses the inside of the skull via the foramen spinosium at the rear. It then courses forward through the dura mater, the outermost layer of the meninges, via a groove on the great wing of the sphenoid bone, a bone on either the side of the cranium.

At that point, the artery splits into two branches: anterior and posterior. The larger of the two is the anterior branch. This branch crosses the sphenoid’s great wing reaching the groove of the parietal bone, which makes up the central and upper back portions of each side of the cranium.

The posterior branch meanwhile curves back towards the temporal bone, located at the side and towards the back of the skull, before reaching the back portions of the parietal bone.

Anatomical Variations

While rare, there are a number of anatomical variations of this artery.

In some cases, the usual point of entry for the middle meningeal artery, the foramen spinosium, is absent. In this case, the artery accesses the cranium via the structure called the foramen ovale alongside the mandibular (jawbone) nerve.

The middle meningeal artery can also emerge at the lateral part of the internal carotid artery—a major source of blood for parts of the brain—therefore accessing the cranium through the foramen lacerum (a triangular opening at the base of the skull) before resuming a normal course.

Furthermore, the origin of the artery has been observed at the posterior cerebellar artery, the basilar artery, the ophthalmic artery, and other arteries of the head.

As a major supplier of blood to the membranes and structures surrounding the brain, the middle meningeal artery certainly serves an essential role.

Branches of this part of the circulatory system also help supply the facial nerve and the tensor tympani muscle in the ear canal.

Traumas or conditions affecting the middle meningeal artery cause a number of well-documented and potentially serious conditions.

Epidural Hematoma

Because of proximity to the boney vault of the skull—the interior portion of the cranium—skull fracture at the side can severely impact the artery and cause ruptures. In 85% of these cases epidural hematoma, which is basically a pooling of blood outside of the veins, results.

This leads first to a loss of consciousness, followed by a period of lucidity and clarity, before a rapid deterioration of brain health. In more severe cases, surgery is required to repair the artery.

Arteriovenous Fistula

Another result of skull fracture, an arteriovenous fistula is defined as abnormal connections between arteries. While this happens relatively often, in a vast majority of cases the condition is not symptomatic and resolves on its own.

However, if this condition lasts for a long time, intracranial hemorrhage (bleeding within the brain) or venous congestion (when more blood enters an artery than can leave) arise; these require medical attention.

Aneurysm

Though this doesn’t occur too often in the middle meningeal artery, an aneurysm is a pooling of blood causing ballooning of a part of the artery.

An aneurysm can arise due to trauma to the skull, leading to rupture of the vessel and clotting in the area. Alternately, this can arise due to specific factors associated with the artery.

In both cases, the aneurysm increases risk of rupture leading to intracranial hemorrhage.  

Migraine

Researchers have also linked the middle meningeal artery to migraine, the onset of severe headache, nausea, sensitivity to light and sound, and other issues. This is because of the artery’s role in supplying the dura mater, which is associated with pain sensation.

Notably, the dilation of this arterial system leads to headaches, so pain can be managed with medications that contract the area.