What is the middle layer of the heart called?

Which of the following diving conditions is also commonly called rapture of the deep?

A) Arterial gas embolism B) Nitrogen narcosis C) Decompression sickness D) Barotrauma

Myocardial ischemia occurs when the heart muscle:

A) is deprived of oxygen because of a blocked coronary artery. B) undergoes necrosis because of prolonged oxygen deprivation. C) suffers oxygen deprivation secondary to coronary vasodilation. D) experiences a decreased oxygen demand and an increased supply.