14a above — a very rarely seen, at least angiographically, tiny vessel arising from the “hypophyseal” segment of the internal carotid artery — a proximal intradural segment also known as supraclinoid, paraophthalmic, etc. See ICA page for details of this semantic disorder.
The artery arises from the medial carotid wall — pituitary is medial to the carotid — and supplies the hypophysis, by definition — the posterior hypophysis usually. The inferior hypophyseal arteries (from the MHT) are usually much bigger.
The “hypophyseal aneurysm” — a medially or inferiorly projecting aneurysm from the hypophyseal segment — is thought to be related to this branch — at least by those who believe that aneurysms must arise from branch points. Aneurysms, of course, don’t care for our opinions, but we are right more often than not.
If you want to see hypophyseal arteries, do some high res DYNA of VASO imaging.
Case courtesy Dr. Eytan Raz — here is a beautiful example of a very dominant superior hypophyseal artery (arrow) supplying the posterior hypophysis (arrowhead), with a correspondingly small inferior hypophyseal contribution from the MHT (dashed arrow)
Cross eye stereo
View from the back — again small inferior hypophyseal, big superior hypophyseal — balance again… See the beautiful vascular ring of the posterior pituitary — the connecting it with the contralateral side
MIP image shows the sella nicely — and helps prove its posterior pituitary
Pure arrowless images — easier to steal…
Of course, there is an aneurysm here — the branch point camp would point out how this larger than usual branch is a setup for aneurysmal formation. Naturally…