Table 2:

Different types of OA origin of the MMA^{^a}

Type	Vascular Anatomy	Foramen Spinosum
I	Complete OA origin of the MMA	Absence
II	Partial OA origin of the MMA; anterior division from the OA; posterior division from the IMA	Reduced in size
III	OA origin of the accessory meningeal artery	Normal

↵a From Ref.²⁸