The Middle Meningeal Artery is the largest branch of the internal maxillary. It arises on the inside of the neck of the lower jaw, and ascends obliquely inwards to the base of the skull, behind the external pterygoid muscle, which consequently separates it from the continued trunk of the internal maxillary artery. In this part of its course it usually passes between the roots of the tem-poro-auricular nerve, lies posterior to the otic ganglion, and then enters the spinous foramen in the base of the skull, after passing between the origin of the circumflexus palati muscle in front, and the internal lateral ligament of the lower jaw posteriorly. In this part of its course, it supplies the pterygoid muscles, the muscles of the pharynx, and the temporal and sphenoid bones.

Having passed within the skull, the middle meningeal artery ascends beneath the dura mater into the middle fossa of the cranium, and terminates by dividing into an anterior and posterior terminating branch.

Before its division it sends a branch through the spheno-frontal fissure to terminate in the lachrymal gland; another through the hiatus Fallopii, which supplies the facial nerve and anastomoses with the stylomastoid artery; and a third through the canal for the internal muscle of the malleus, to be distributed on the lining membrane of the tympanum.

The anterior terminating branch, much larger than the posterior, ascends through the groove in the great wing of the sphenoid bone, and the anterior inferior angle of the parietal bone, the groove in the latter being frequently converted into a complete osseous canal. The artery is here situated about one inch behind the external angular process of the frontal bone, and divides into numerous branches that radiate in all directions on the internal surface of the parietal and adjacent bones: these branches are principally lost on the dura mater; a few of them penetrate the sutures and supply the diploe of the bones. This artery has been frequently torn in injuries of the head, and has given rise to considerable hemorrhage between the dura mater and the bone. It may also be wounded in the operations of trephining: the hemorrhage may. however, be easily controlled by the application of a dossil of lint. The posterior terminating branch curves backwards as it ascends on the internal surface of the squamous plate of the temporal bone. Its branches communicate with each other, and terminate in the dura mater and bone.

The Tympanic Artery

The Tympanic Artery is a very small branch; it sometimes arises from that branch of the temporal which goes to supply the temporo-maxillary articulation; it passes through the Glasserian fissure into the tympanum, and ramifies upon the membrane lining the interior of this cavity, and in the muscles contained within it.