a. Anat. [f. Thebesius, name of a German anatomist (1686–1732) + -AN.] Applied to structures in the heart discovered or investigated by Thebesius:
Thebesias foramina, small openings into the right auricle, believed to be the orifices of the Thebesian veins; Thebesian valve, the coronary valve: Thebesian veins, small veins bringing blood from the substance of the heart into the right auricle.
1871. Huxley, Anat. Vertebr. Anim., 407. In the heart [of the porpoise] the fossa ovalis is distinct, but there is neither Eustachian nor Thebesian valve.
