CH 18: Gross Anatomy of the Heart

J.F. Thompson, Ph.D.

Located in the Ventral Body Cavity

Ventral body cavity thoracic

pleural pericardial mediastinum

abdominopelvic abdominal pelvic

The Size of the Heart

• About same size as a closed fist• the base is the wider

superior portion• the apex is the point

PericardiumThe sac containing the heart

Fibrous Pericardium rests on and is attached

to diaphragm a tough, inelastic sac of

fibrous connective tissue

anchored to the blood vessels entering and leaving the base of the heart

protects and anchors the heart; prevents overfilling of the chambers of the heart

Parietal (Outer) Serous Pericardium

simple squamous epithelium

forms outer parietal layer bound to fibrous pericardium

secretes a serous (watery) lubricating fluid

reduces friction as the heart contracts and twists

Visceral (Inner) Serous Pericardium

simple squamous epithelium forms the epicardium

forms visceral layer bound to the myocardium of the heart

secretes serous fluid

reduces friction as the heart pumps, contracts and twists

Heart wall - Three layers Epicardium (outer)

visceral layer of pericardium

thin, transparent smooth, slippery

Myocardium (middle) mass of cardiac

muscle Endocardium (inner)

endothelium over thin connective tissue

smooth lining for the chambers and valves

continuous with blood vessel endothelium

Myocardium (Cardiac Muscle)

Cardiac muscle cells are involuntary, striated, branched

Each fiber is connected to the others by intercalated discs gap junctions allow

action potentials to pass from fiber to fiber

desmosomes (“spot welds”) to prevent cardiac fibers from separating during contractions

Intercalated Discs

[Note the striations and recall the sliding filament method of muscle contraction.]

Surface of the Heart

External landmarks Atrioventricular

grooves separate atria from ventricles

Anterior/posterior interventricular sulcus separates right and left ventricles

Coronary vessels run in these grooves

End Anatomy of the Heart

CH 18