This section is from the book "Anatomy Of The Arteries Of The Human Body", by John Hatch Power. Also available from Amazon: Anatomy of the Arteries of the Human Body, with the Descriptive Anatomy of the Heart.
In some cases this artery arises from the internal carotid.* Dr. Green relates a case in which it arose from the vertebral.* Lastly, it may give off the pharyngea ascendens.†
* Tiedemann, Exp. Tab. Art., p. 81.
This artery sometimes arises by a trunk common to it and the occipital. It sometimes gives off the transversalis faciei.
The pharyngea ascendens is sometimes a branch of the common carotid artery, and in still rarer cases it may arise from the internal carotid, in which case there is usually an accessary pharyngeal from the external carotid. It has also been observed to arise from the occipital,‡ or from the superior thyroid,§ or facial. || Finally, there are sometimes two, and at other times three, instead of a single artery.¶¶
In many cases this artery arises from the temporal. Dr. Hart has seen it arise from the external carotid, opposite the angle of the jaw, beneath which it passed forwards and joined the labial at the anterior edge of the masseter muscle. He has also seen it arise from the posterior auricular. When the facial artery is small, this vessel is proportionally large, and gives off the dorsalis nasi or angularis artery, or both.