The medial wall of the right atrium.
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005318:Fetal Heart / Q000033:anatomy & histology; D006325:Heart Atria / Q000033:anatomy & histology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009206:Myocardium