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
Coronary Circulation: Venous Drainage
- Great cardiac vein (paired with anterior descending)
- Small cardiac vein (paired with right coronary artery)
- Middle cardiac vein (paired with posterior descending)
- Coronary sinus (veins empty into coronary sinus, which drains into right atrium)
Superior and Inferior Vena Cava
-Large veins that drain deoxygenated blood from the body into right atrium of heart
*Inferior= drains lower limbs, pelvic and abdominal viscera
*Superior= drains thorax, head, neck and upper limbs
Right Atrium (+2 Components)
Features:
1. Pectinate muscles (contractibility of heart, more surface area)
2. Fossa ovalis (depression on interatrial septum, embryological remnant of foramen ovale from baby bypassing pulmonary system when they didn’t have lungs)
*foramen ovale becomes fossa ovale after birth when foramen ovale closes
*SVC, IVC and coronary sinus drains into RA, passes to RV through tricuspid valve
Tricuspid Valve
One-way valve b/t right atrium and right ventricle
-3 cusps
Right Ventricle (3 Features)
Features:
1. Chordae tendinae- attach to valve cusps
2. Papillary muscles- anchor chordae tendinae (to contract and pull cords and open valve)
3. Trabeculae carnea- papillary anchored
*these structures prevent prolapse of the valve during contraction of the ventricle
*Blood then flows through pulmonary valve to pulmonary trunk and pulmonary arteries
Pulmonary Arteries and Veins
Arteries= carry deoxygenated blood from right ventricle to lungs
Veins= carry oxygenated blood from lungs to left atrium
Left Atrium (1 Feature)
Features:
-Pectinate muscles
*blood flows from pulmonary veins into LA, contracts and passed through bicuspid/mitral valve to LV
Bicuspid Valve
One-way valve between left atrium and left ventricle
2 cusps
Left Ventricle
Features:
-Chordae tendinae
-Papillary muscles
-Trabeculae carneae
*comes through bicuspid valve to LV, then goes through aortic valve to go through aorta (large artery that carries oxygenated blood from LV to the body)
Arch of Aorta
Branches supply head, neck and upper limbs
- Brachiocephalic trunk
- Left common carotid artery
- Left subclavian artery
*brachiocephalic trunk branches into:
4. Right common carotid artery
5. Right subclavian artery
Descending Aorta
Supplies blood to thorax, abdomen and lower limbs
Descends to common iliac artery
Blood Flow Overview (12 Steps)
- SVC and IVC carry deoxygenated blood from body
- Right atrium
- Tricuspid valve
- Right ventricle
- Pulmonary valve
- Pulmonary trunk and arteries to lungs
- Pulmonary veins carry oxygenated blood from lungs
- Left atrium
- Bicuspid valve
- Left ventricle
- Aortic valve
- Ascending aorta, arch of aorta (3 branches), descending aorta to rest of body
Thoracic Cavity: Arterial Supply
Posterior thoracic wall:
-Aorta continues as descending thoracic aorta
-Gives off posterior intercostal arteries (which supply posterior thoracic wall)
Anterior thoracic wall:
-Subclavian arteries give off right and left internal thoracic arteries
-Gives off anterior intercostal arteries (which supply upper intercostal spaces)
-Musculophrenic artery supplies lower intercostal spaces
Thoracic Cavity: Venous Drainage
Anterior and posterior intercostal veins drain into:
-Azygous vein (right)
-Hemiazygous and accessory hemiazygous veins (left) to azygous
*drain into SVC
Innervation of Thoracic Cavity
Intercostal nerves
-Formed by ventral rami of thoracic spinal nerves
Motor: innervate intercostal muscles
Sensory: innervate overlying skin
