branch enters the hiatus of the facial canal, supplies the facial nerve, and anastomoses with the stylomastoid branch of the posterior auricular artery. A superior tympanic artery runs in the canal of the tensor tympani muscle, and supplies this muscle and the lining of the canal. Orbital branches pass through the superior orbital fissure or through separate canals in the great wing of the sphenoid, to anastomose with the lacrimal or other branches of the ophthalmic artery. Temporal branches pass through foramina in the great wing of the sphenoid, and anastomose in the temporal fossa with the deep temporal arteries. 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. History Additional images See also Foramen spinosum Maxillary artery References External links () Photos with captions at bubbasoft.org Arteries of the head and neck