organ part myocardium of ventricle ventricle cardiac muscle ventricular myocardium As noted, the hearts of birds and mammals have four chambers that arises from the two chambers (atrium and ventricle) of the fish heart.[uncertain][VHOG] ventricle myocardium Muscular layer of the cardiac ventricle composed of a compact myocardial layer surrounding the trabecular layer Hu et al. 2001.[TAO] VHOG:0000604 EMAPA:32748 FMA:12151 Muscular layer of the cardiac ventricle composed of a compact myocardial layer surrounding the trabecular layer. TAO:0005061 uberon MA:0000082 EFO:0003088 SCTID:192084000 ZFA:0005061 UBERON:0001083