ANATOMY

Detailed explanation-1: -The muscles of the heart, termed the myocardium, make up the middle and thickest layer of the heart wall. This layer lies between the single-cell endocardium layer, which lines the inner chambers, and the outer epicardium, which makes up part of the pericardium that surrounds and protects the heart.

Detailed explanation-2: -Pericardium, or the layer surrounding the heart. Epicardium, the outside layer of the heart. Myocardium, the middle layer of the heart. Endocardium, the innermost layer of the heart.

Detailed explanation-3: -The myocardium is mainly made up of two types of cells: cardiomyocytes and fibroblasts. Fibroblasts are distributed between cardiomyocytes, along with extracellular matrix (ECM), blood vessels, lymphatic vessels, and nerve endings.

Detailed explanation-4: -The myocardium is the middle and thickest layer of the heart wall. (Myo-means “muscle.") Most of the heart wall is the myocardium. It also houses the cardiac electroconductive system (SA node, AV node, HIS fibers, and Purkinje fibers). PERICARDIUM: makes up the outer layers of the heart wall, enclosing the heart.

Detailed explanation-5: -Cardiac muscle (or myocardium) makes up the thick middle layer of the heart. It is one of three types of muscle in the body, along with skeletal and smooth muscle. The myocardium is surrounded by a thin outer layer called the epicardium (AKA visceral pericardium) and an inner endocardium.