CH 18: Gross Anatomy of the Heart

1
CH 18 Gross Anatomy of the Heart
J.F. Thompson, Ph.D.
2
Located in the Ventral Body Cavity

• Ventral body cavity
• thoracic
• pleural
• pericardial
• mediastinum
• abdominopelvic
• abdominal
• pelvic

3
The Size of the Heart

• About same size as a closed fist
• the base is the wider superior portion
• the apex is the point

4
Pericardium
The sac containing the heart
5
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

6
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

7
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

8
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

9
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

10
Intercalated Discs
Note the striations and recall the sliding
filament method of muscle contraction.
11
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

12
End Anatomy of the Heart CH 18