The subfornical organ sits in the midline, on the underside (ventrally) of the fornix, at the level of the ventricular cavities.
The subfornical organ, together with the organum vasculosum and nucleus preopticus medianus, participates in the control of the salt-water balance, of our thirst and of vasopressin (ADH) secretion from the nucleus supraopticus + nucleus paraventricularis hypothalamicus.
The subfornical organ lacks a blood-brain barrier and is counted among the circumventricular organs