The Heart and Thorax Flashcards
Thoracic Cavity Components (4)
- Thoracic Cavity:
-Contains organs of respiratory, cardiovascular, digestive and lymphatic systems
Subdivided into:
2. Pleural Cavities- which surround the lungs
3. Mediastinum- central component of thoracic cavity
4. Pericardial cavity- surrounds the heart
Boundaries of Thoracic Cavity
Anteriorly and posteriorly:
-Thoracic cage (ribs, sternum, thoracic spine, muscles)
Inferiorly:
-Diaphragm (inferior to heart and lungs)
The Heart: Anatomical Relationships
Located in middle of mediastinum, within pericardial cavitry
-Directly posterior to sternum
-Between lungs
-Superior to diaphragm
*Apex of heart points antero-inferiorly and to LEFT
-Base of heart is posterior and superior
Function of Heart
-4 chambered organ
-Pumps blood throughout body within a network of blood vessels
-Chambers contract to pump blood (flow of blood through heart is controlled via valves)
-Blood is driven through 2 circuits (pulmonary and systemic circuits)
Pulmonary vs. Systemic Circulation
Pulmonary:
-Pumps deoxygenated blood from the heart to the lungs to become oxygenated
-Pumps oxygenated blood from lungs back to heart
*heart and lungs
Systemic:
-Pumps oxygenated blood from heart to rest of body
-Returns deoxygenated blood back to heart
*heart and rest of body
Pericardium
-Layered, fluid-filled sac that surrounds the heart
-Formed by the OUTER FIBROUS pericardium and INNER SEROUS pericardium
Fibrous Pericardium
Outermost layer, dense CT that surrounds the heart and roots of great vessels
*Base is fused with central tendon of diaphragm (central tendon= aponeurosis or flattened tendinous thickening of diaphragm)
Functions of Fibrous Pericardium
-Anchors heart in place
-Provides protection
-Prevents overextension of heart (acts as a stop)
Serous Pericardium
Inner serous pericardium formed by 2 layers:
- Parietal pericardium: fused with fibrous pericardium
- Visceral pericardium: adhered to surface of heart
Pericardial Cavity/Space
-Space between visceral and parietal pericardium layers
-Contains small amount of pericardial fluid (acts as a lubricant, reducing friction b/t opposing surfaces of heart and pericardium as heart beats)
Pericardial Cavity: Potential Space
Potential space is when adjacent structures are normally pressed together, but are not fused, so leaves room for potential space
-Opposing layers of visceral and parietal pericardium are in close contact
Pericardial cavity can expand under pathological conditions (e.g. pericardial effusion- accumulation of excess fluid in cavity due to infection, injury, etc.)
External Anatomy of the Heart
4 Chambers:
-2 Atria (left and right atrium): each atria has an auricle, atria form base of heart (posteriorly)
-2 Ventricles (Left and right ventricle): form apex of heart
*apex inferior and to the left
*Anterior Atrioventricular and Interventricular groove, and posterior interventricular groove= lines that separate
Septa
Chambers of the heart are separated by septa:
-Interatrial septum separates right and left atria
-Interventricular septum separates right and left ventricles
Great Vessels of the Heart (6)
- Superior Vena Cava (SVC)
- Inferior Vena Vava (IVC)
- Pulmonary Trunk
- Pulmonary Arteries
- Pulmonary Veins *posterior
- Aorta
*ascending, arch, descending
Coronary Circulation: Arterial Supply (5)
- Right coronary artery (in atrioventricular groove)
- Left coronary artery *both originate from ascending aorta)
*Left coronary has 2 branches:
3. Left anterior descending artery (in anterior interventricular groove)
4. Circumflex artery
- Posterior descending artery (in posterior interventricular groove)
*Left side= Left coronary, left anterior descending and circumflex
*Right side= Right coronary and posterior descending