Thorax
Thoracic wall, breast, pleura and lungs, heart and pericardium, and the mediastinum.
31 entriesThoracic wall: 6Breast: 1Pleura & lungs: 3Heart & pericardium: 12Mediastinum: 9
Bones (2)
- Ribs HYTwelve pairs of curved bones forming most of the thoracic cage. They are grouped as true, false and floating ribs, and rib fractures are the most common thoracic injury.
- Sternum HYFlat bone of the anterior thoracic wall made of the manubrium, body and xiphoid process. The sternal angle is the key surface landmark of the thorax.
Muscles (2)
- Diaphragm HYDome-shaped musculotendinous partition between the thorax and abdomen. It is the main muscle of inspiration and is supplied by the phrenic nerves (C3–C5).
- Pectoralis major Large fan-shaped muscle of the anterior chest that adducts and medially rotates the arm. It forms the anterior axillary fold and lies deep to the breast.
Nerves (1)
Arteries (7)
- Anterior interventricular artery HYBranch of the left coronary artery in the anterior interventricular groove. It supplies the anterior LV wall, the anterior two-thirds of the septum and the apex, and is the most commonly occluded coronary artery.
- Circumflex artery HYBranch of the left coronary artery in the left atrioventricular groove that supplies the lateral wall of the left ventricle and the left atrium; its occlusion causes lateral (and sometimes posterior) MI.
- Internal thoracic artery HYBranch of the subclavian artery that descends just lateral to the sternum. It supplies the anterior chest wall and breast and is the preferred conduit for coronary bypass (LIMA to LAD).
- Left coronary artery HYShort trunk from the left aortic sinus that divides into the anterior interventricular (LAD) and circumflex arteries, supplying most of the left ventricle.
- Pulmonary arteries HYThe pulmonary trunk and its right and left branches carry deoxygenated blood from the right ventricle to the lungs. They're where pulmonary emboli lodge.
- Right coronary artery HYArises from the right aortic sinus and runs in the right atrioventricular groove. It usually supplies the SA and AV nodes, the right ventricle and (in right dominance) the inferior wall; occlusion causes inferior MI.
- Thoracic aorta HYThe aorta within the thorax (ascending aorta, arch and descending thoracic aorta). It's the site of dissection, coarctation, traumatic injury and aneurysm.
Veins (2)
- Azygos vein Vein on the right side of the posterior mediastinum that drains the posterior thoracic wall. It arches over the right lung root into the SVC and is a key collateral pathway between the caval systems.
- Superior vena cava HYLarge vein returning blood from the head, neck, upper limbs and upper thorax to the right atrium. It is the site of SVC syndrome and the target position for central venous catheter tips.
Lymphatics (1)
Organs (13)
- Aortic valve HYThree-cusped semilunar valve between the left ventricle and the aorta. Aortic stenosis and regurgitation are among the most tested murmurs.
- Breast HYModified sweat gland on the anterior thoracic wall. Most of its lymph drains to the axillary nodes, which is central to the spread and staging of breast cancer.
- Cardiac conduction system HYSpecialized cardiac muscle that generates and conducts impulses (SA node → AV node → bundle of His → bundle branches → Purkinje fibers). Its blood supply explains the arrhythmias that accompany some MIs.
- Esophagus HYMuscular tube from the pharynx (C6) through the posterior mediastinum to the stomach (T11). Its constrictions, portosystemic anastomosis and relations explain many board classics.
- Heart HYFour-chambered muscular pump in the middle mediastinum. Knowing which chamber forms each surface and border is the key to exam findings, ECGs and chest X-rays.
- Lungs HYPaired organs of respiration. The right lung has three lobes and the left has two plus the lingula; lobe location drives exam findings and imaging signs.
- Main bronchi HYThe two airways arising at the carina. The right main bronchus is wider, shorter and more vertical, so foreign bodies and aspirate usually enter the right lung.
- Mitral valve HYTwo-leaflet valve between the left atrium and left ventricle, anchored by chordae tendineae to two papillary muscles. Mitral stenosis, regurgitation and prolapse are heard best at the apex.
- Pericardium HYDouble-walled fibroserous sac enclosing the heart. Pericarditis, effusion and tamponade are its key clinical problems.
- Pulmonary valve Three-cusped semilunar valve between the right ventricle and the pulmonary trunk. It is the most anterior valve, and the physiologic splitting of S2 is heard best over it.
- Thymus HYPrimary lymphoid organ in the anterior and superior mediastinum where T cells mature. It is large in children, involutes after puberty, and thymoma is associated with myasthenia gravis.
- Trachea HYCartilage-reinforced airway from the larynx (C6) to its bifurcation at the carina (about T4–T5). Its midline position is an important exam and radiographic sign.
- Tricuspid valve HYThree-leaflet valve between the right atrium and right ventricle. Tricuspid regurgitation, including from IV drug–associated endocarditis, is its key clinical problem.
Spaces & regions (3)
- Intercostal space HYSpace between adjacent ribs containing three muscle layers and the intercostal neurovascular bundle, which runs along the lower border of the rib above.
- Mediastinum HYCentral compartment of the thorax between the pleural cavities, divided into superior and inferior parts. Knowing what is in each compartment leads you to the differential for a mediastinal mass.
- Pleural cavity HYPotential space between the visceral and parietal pleura around each lung. It's the site of pneumothorax and pleural effusion and the target of thoracentesis and chest tubes.