====== Area postrema ======

The [[area postrema]] is a narrow strip of neural tissue located between the [[vagal triangle]] and the margin of the [[rhomboid fossa]]. It lacks the blood-brain barrier and has been shown in dogs to function as a trigger zone for vomiting. The facial colliculus, lying rostral to the hypoglossal and vagal triangles, is produced by fibres of the facial motor nucleus looping over the abducens nucleus.

{{::areapostrema.jpg|}}

Ap: [[area postrema]]; icp: [[inferior cerebellar peduncle]]; lr: [[lateral recess]]; ms: [[median sulcus]]; scp: [[superior cerebellar peduncle]]; sf: [[superior fovea]]; sm: [[Medullary striae of fourth ventricle]].

The human area postrema (AP) is a circumventricular organ that has only been described in cadaveric specimens and animals. Because of its position in the [[calamus scriptorius]] and the absence of surface markers on the floor of the fourth ventricle, the AP cannot be clearly localized during surgical procedures. 
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Signals detected by taste receptors, peripheral osmo-sodium, volume receptors, and arterial/cardiopulmonary baroreceptors reach the [[nucleus of the solitary tract]] (NTS) by the VIIth, IXth, and Xth cranial nerves. The other main brain entry of the information related to fluid and cardiovascular balance are the [[lamina terminalis]] (LT) and one of the sensory circumventricular organs (CVOs), the [[area postrema]] (AP).