Middle Meningeal Artery
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Direct answer
Rupture of the middle meningeal artery against the pterion produces the textbook extradural (epidural) haematoma. It arises from the first part of the maxillary artery in the infratemporal fossa, enters through the foramen spinosum, and grooves the squamous temporal bone, dividing into a large anterior (frontal) branch ascending across the pterion and a posterior (parietal) branch curving backwards. It supplies the dura and inner table, with a petrosal branch running with the greater petrosal nerve and a superior tympanic branch. At the pterion — the thin junction of four calvarial bones — the anterior branch lies in a groove or bony canal, so a blow here tears it, stripping the dura outward into a lens-shaped clot.
What you must remember
- Origin and entry: from the first part of the maxillary artery, entering through the foramen spinosum alongside its companion veins — the only artery of the dura with this typical course.
- Pterion vulnerability: the anterior branch grooves (or canals) the inner table at the pterion, where the bone is thinnest; fractures here tear the vessel beneath.
- Surface marking: the anterior branch corresponds to a line running upward and backward from a point about 3.5 cm behind and 1.5 cm above the frontozygomatic suture — the marking for an emergency burr hole.
- Named branches: petrosal branch with the greater petrosal nerve to the facial nerve region, superior tympanic branch to the tensor tympani, and ganglionic twigs to the trigeminal ganglion; the accessory meningeal artery, from the maxillary, enters via the foramen ovale.
- Extradural haematoma signature: lucid interval after brief unconsciousness, then headache, contralateral weakness, and an ipsilateral dilating pupil from tentorial herniation of the temporal lobe.
- Clot shape: biconvex (lens-shaped) and limited by sutures where the dura is firmly attached — it does not cross the coronal, lambdoid or squamosal sutures, unlike a subdural collection.
- Modern role: embolisation of the middle meningeal artery is an emerging treatment for chronic subdural haematoma, and ligation at the foramen spinosum is the classical operative step.
Managing the classic case from artery to burr hole
Follow the archetypal timeline. A man is struck at the temple, briefly knocked out, wakes and speaks, then over the next hour becomes drowsy with a dilating right pupil and a weak left arm. The sequence is the artery's anatomy unfolding: the tear at the pterion bleeds into the potential space between dura and bone, the clot's firm dural attachment limits it into a lens shape, and as volume grows the temporal lobe herniates through the tentorial notch, compressing the third nerve (pupil) and the cerebral peduncle (contralateral weakness). The computed tomogram shows the hyperdense biconvex mass, and the neurosurgeon centres the burr hole on the surface marking of the anterior branch — behind and above the frontozygomatic suture — before turning a crani flap to coagulate or ligate the vessel.
The variants follow the same map: a posterior branch bleed gives an occipito-parietal clot with gradual drowsiness, a torn middle meningeal vein mimics it slowly, and in infants the vessel may tear without a fracture.
How the examiner frames the vessel
The first question is origin: from which part of the maxillary artery does it arise, and through which foramen does it enter — the first part and the foramen spinosum, with candidates who say foramen ovale losing the mark to the accessory meningeal artery, which does use the ovale. The second is the surface marking, expected verbatim as the point about 3.5 cm behind and 1.5 cm above the frontozygomatic suture, because it doubles as the burr hole site and the pterion's own marking. The third is why an extradural clot is lens-shaped and stops at sutures while a subdural crescent follows the brain's surface — the strength of dural attachment at sutures versus the free subdural space. Indian prof examiners commonly add the radiological bonus of the artery's groove on skull radiographs and its occasional bony canal at the pterion.
Frequently asked questions
What is the origin and cranial entry of the middle meningeal artery?
It arises from the first part of the maxillary artery in the infratemporal fossa and enters the skull through the foramen spinosum.
Why does the pterion matter in extradural haematoma?
The anterior branch of the artery grooves the inner table at the pterion where the bone is thinnest, so temporal blows fracture and tear the vessel there.
What is the surface marking of the anterior branch?
A line running upward and backward from a point about 3.5 cm behind and 1.5 cm above the frontozygomatic suture, marking the emergency burr hole site.
Why is an extradural haematoma lens-shaped?
The dura is firmly attached to bone at the sutures, so the clot is limited by them and bulges inward as a biconvex mass rather than spreading like a subdural collection.
What is the lucid interval?
A period of apparent recovery between the initial concussion and the compressive deterioration, classically seen as an arterial extradural haematoma expands.