Pretty much never visible on 2D-DSA. About 10-20% of time visible on high-res Cone Beam CT Angiography (CBCTA). Described by McConnell in his seminal, and still THE BEST, manuscript on pituitary gland arterial supply. See Superior Hypophyseal Artery (14a) and Inferior Hypophyseal Artery (14) pages for pituitary supply. The (Capsular) Artery (arteries) of McConnell pretty much NEVER supply the pituitary though 🙂 They are “osteodural” — supplying the dura of the sella tursica (bottom of it), and adjacent bone. Origin is most commonly from the medial aspect of the horizonal cavernous segment of the ICA. This artery or arteries is a distinct thing. Its not MHT (2) or ILT (3). Occasionally their territory might be supplied by an unusual branch from ILT— weird.
Below is a classic example