Term: atrium myocardium
Name: atrium
Synonyms:
Definition: Cavitated compound organ that receives inflow of deoxygenated blood and delivers it to a muscular cardiac ventricle. Valves are present to direct flow. There are only two chambers present in the fish heart.
Ontology: Anatomy Ontology [ZFA:0000471]

Name: myocardium
Synonyms: cardiac muscle, heart muscle
Definition:
Ontology: Anatomy Ontology [ZFA:0001319]