Different types of OA origin of the MMA by Maiuri et al19
| Type | Vascular Anatomy | Foramen Spinosum |
|---|---|---|
| I | Complete OA origin of the MMA | Absent |
| II | Partial OA origin of the MMAAnterior division from the OAPosterior division from the IMA | Reduced in size |
| III | OA origin of the accessory meningeal artery | Normal |
Note:—IMA indicates internal maxillary artery.