CVPR Overview of the Thorax Flashcards
Superior thoracic aperture (thoracic inlet)
- upper border of the manubrium, the first pair of ribs and the first thoracic vertebra
Inferior thoracic aperture (thoracic outlet)
the 12th vertebra and the lower border of the rib cage to the xiphoid process of the sternum
Diaphragm
dome shaped sheet of muscular and fibrous tissue that closes the inferior thoracic aperture
Bones of the thoracic wall
- 12 thoracic vertebrae
- sternum
- 12 pairs of ribs and their costal cartilages and intercostal spaces
Sternal angle
- Junction between the manubrium and body of the sternum at T4/5 vertebral level, is a bony landmark useful for locating:
- the 2nd rib
- where the aortic arch begins and ends
- where the trachea bifurcates
- the boundary of the superior vs inferior mediastinum
Intercostal muscles
fill the intercostal spaces and function in respiration to raise and lower the ribs
Intercostal veins, arteries, nerves run along
inferior margin of the rib, in the costal groove and in the plane between the innermost and internal intercostal muscles
Intercostal veins
- drain into the azygous system or the internal thoracic veins
Intercostal arteries
- branch off the aorta and internal thoracic arteries
Intercostal nerves
- anterior rami of the thoracic spinal nerves
The nerves, veins, and arteries have collateral branches that run superior to the rib below the cutaneous branches at the angle of the rib between the posterior axillary and midaxillary lines and near the sternum that supply the skin
Intercostal nerve block is injected where
just inferior to the rib
Diaphragm
- Separates the thorax from abdomen and is the major muscle of respiration.
- Supplied by the phrenic nerves (ventral rami of C3, 4, 5)
3 apertures of the diaphragm
- Caval opening (T8)- for the inferior vena cava and sometimes the right phrenic nerve; through the central tendinous part (the central tendon of the diaphragm)
- Esophageal hiatus (T10)- for the esophagus and the vagus nerves; through the muscular part
- Aortic hiatus (T12)- for the aorta, thoracic duct, azygous vein, through the right and left crura, leg shaped tendons of the diaphragm attaching to the posterior abdominal wall
Mediastinum
- Everything that lies between the lungs
- Superior mediastinum and inferior mediastinum separated by a horizontal plane through the sternal angle
Inferior Mediastinum
- Anterior mediastinum- primarily occupied by fat and in the adult, remnant of the thymus gland
- Middle mediastinum- contains the heart and roots of the great vessels (superior and inferior vena cavas, ascending aorta, pulmonary trunk, pulmonary veins) enclosed in the pericardial sac, and the phrenic nerves
- Posterior mediastinum- contains multiple structures including the descending aorta, azygous vein, thoracic duct, esophagus trachea and vagus nerves
Pleural sac
encases the lung and formed by serous membrane called the pleura
Visceral and Parietal Pleura
- Visceral pleura: part of the serous membrane that covers the lung
- Parietal Pleura: pleura that lines the thoracic wall
Space between parietal and visceral pleura
pleural cavity- contains serous fluid
Recess
- Result because the lungs do not completely fill pleural cavities
- Provide potential spaces where fluid can collect and fluids can be aspirated
Costomediastinal recess
- anterior and largest on the left side in the region overlying the heart
Costodiaphragmatic recesses
- inferior, between the lowest part of the costal pleua and the diaphragmatic pleura
Thoracocentesis
- for pleural effusion
- needle is inserted along the superior margin of the rib into the pleural cavity to remove excess fluid
What innervates costal parietal pleura
- intercostal nerves
What innervates the mediastinal and diaphragmatic parietal pleura
phrenic nerves
innervation of visceral pleura
autonomic nerves
Pericardial sac
- surrounds the heart and roots of the great vessels
- has two layers that make up the parietal pericardium and enclose the pericardial cavity which contains pericardial fluid
- inner serous layer and 2. outer fibrous layer
Visceral pericardium or epicardium
- closely adhered to the heart
Transverse pericardial sinus
passage between the two sited of reflected pericardium, posterior to the ascending aorta nd pulmonary trunk, and anterior to the superior vena cava and pulmonary veins
Oblique pericardial sinus
- posterior to the left atrium
Blood flow in the heart
- deoxygenated blood from the body enters the right atrium via the superior and inferior vena cavas
- from the right atrium blood moves through the right atrioventricular valve to the right ventricle then through the semilunar valve out the pulmonary trunk to the lungs
- oxygenated blood enters the left atrium from the lungs via the pulmonary veins
- from left atrium blood moves throught the left AV valve to left ventricle, then through semilunar valve out the aorta to the body
Sternocostal surface of the heart
primarily right ventricle
