AMA — 53a. Soft tissue branch — 54. Meningeal branch — 36.
A real artery with serious cranial nerve and EC-IC anastomoses. Classically has extracranial and intracranial parts. Of course, everything varies tremendously.
The extracranial part is in the upper lateral nasopharynx. Supplies area around the Eustachian tube opening, to larger or smaller extent — in balance with the superior division of the ascending pharyngeal artery pharyngeal trunk, the pterygovaginal artery off the IMAX, the vidian. When large can take care of soft palate / pterygoid / posterior nasopharynx areas
The intracranial part classically enters to skull via foramen Ovale — hence its embolization endangers V3. Once inside, it can anastomose with all the usual suspects in the area — ILT, MMA — specifically the accessory meningeal can give rise to the petrous branch and its CNVII. So, be careful…
The classic Lasjaunias theory is in the relationship between the superficial and deep course of the IMAX, origins of middle and accessory meningeal arteries. The further an artery is from somewhere, the more likely it is that the arteries will come a common source. Common origin of MMA and AMA means the IMAX course is superficial.
Below is a DYNA example of a large accessory meningeal. 1-9 is bottom to top. Common origin (yellow arrows) of MMA (black arrowhead) and AMA (white arrowhead) — as expected IMAX course is superficial. The large soft tissue branch breaks into multiple twigs that supply the soft palate (yellow ovals) — typically palate is lesser palatine or ascending pharyngeal territory.
The meningeal branch (white arrow) enters the skull via foramen of Vesalius (cool — at 10 o’clock relative to Ovale) and, not to be outdone by the large cutaneous branch, is also of possessive character — multiple branches to the Meckel cave region (white oval) are present — embo would endanger all those nerves. Specifically seen are artery of foramen rotundum (purple) and the anteromedial branch (blue) — typically this comes off the ILT as “dorsal ophthalmic artery” remnant — and an important “dangerous” anastomosis with the ophthalmic artery. Explanation — ILT is hypoplastic — hence supply to area comes from AMA. Remember, its all about balance. Here, the situation is not balanced, with an oversized AMA
Angio views — same arrows as above — except that yellow arrows point to the soft tissue branches of the AMA, and not to the common AMA/MMA trunk, which is unlabeled
AMA supply of cavernous dural fistula
Full case is here.
Although the AMA might seem like some distance away from the posterior cavernous sinus (the most common site of cavernous dural fistula venous pouch), its propensity to participate in fistula supply highlights role of the cavernous branch of the AMA as a potential ILT/ MHT collateral.
Here, the fistulas is in LEFT posterior cavernous sinus (black arrow — venous pouch). Supply from right ascending pharyngeal opacifies the posterior clival branch of the MHT (white arrow) — principal contributor to fistula
The right AMA (white arrows) also supplies it, via cavernous branches (dashed arrows)
DYNA CT of same
The same fistula is supplied by left AMA as well (same arrows), but to lesser extent — as sometimes happens in cavernous fistulas, the ipsilateral side might not be the dominant supplier.
For completeness sake, supply from right ICA via the MHT — the white arrow is on an artery (intercavernous / medial clival), not vein
Variant — Accessory Meningeal Supply of Frontal Branch and Petrous branches of MMA
The frontal branch variant is rare. The petrous one might not be so rare after all. Just because ovale is more anterior than spinosum doesn’t mean it wont do the job.
In the case below, a variation is present with frontal MMA branch (B, white arrows) supply from the accessory meningeal artery, which also supplies the petrous branch (F, white arrows. Black arrow is on catheter tip in foramen ovale). Images G, H, and I show sphenoid ridge branch (white arrows) opacifying the ophthalmic artery (black arrow) during superselective catheterization of the frontal branch (in this case of AMA origin) — this connection was not visible on a nonselective injection (B) So, be careful…
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