has part has part has_part characteristic of part of has modifier abnormal fourth ventricle morphology abnormal area postrema morphology any structural anomaly of the small, elevated area in the lateral wall of the inferior recess of the fourth ventricle, involved in the control of cardiorespiratory physiology; in addition, the area postrema is the location of the chemotoxic trigger zone at which emesis (vomiting) is induced by various toxins in the blood stream and that affect the hypothalamus to induce taste aversion MPheno.ontology MP:0004186 abnormal sensory circumventricular organ morphology morphology abnormal area postrema