Here is some information you probably had no idea you did not know. While this post may seem purely educational, be vigilant! For I have hidden some funny amongst the anatomy...
Lungs and Pleurae
What is the Inferior extent of the pleural cavity at the midclavicular, midaxillary and midscapular lines?
A: Posteriorly the pleural cavity extends to the level of T12, anteriorly at the midclavicular line it extends to about T8, and at the midaxillary line it extends to about T10.
What structures cause impressions on the lung?
A: Right lung has impressions from the trachea, esophagus, brachiocephalic vein, arch of the azygos vein, superior vena cava, rib 1, and a small cardiac impression. The left lung has impressions from the subclavian artery, arch of the aorta, descending aorta, small impressions from the trachea, first rib, and esophagus, and a large cardiac impression.
What causes the carina to become misshapen?
A: displacement by tumors, inflammation of the inferior tracheobronchial lymph nodes.
What nerve carries the cough reflex?
A: The vagus nerves.
A: The right main bronchus, because it is wider, shorter, and more vertically oriented than the left side.
What are the vertebral levels for sympathetic innervation of the lung?
A: T2-T5
What is a bronchopulmonary segment?
A: Surgically resectable section of the lung which contains a tertiary bronchus and its own arterial supply.
What is a pneumothorax? How can it occur?
A: A pneumothorax is the presence of air in the pleural cavity, which pressurizes the vacuum within that space and causes the lung to collapse. This can occur from a chest wall injury, such as a “sucking chest wound” like a stab or bullet hole. This can also occur iatrogenically, as in the case of central line anesthesia. A hemothorax is the presence of blood in the pleural cavity, and a hydrothorax is the presence of fluid in the pleural cavity, as in the case of pleural effusion.
What is a pulmonary thromboembolism? How can it occur?
A: A blood clot which usually forms in the large vessels of the legs and travels to the lungs. The clot travels though the right side of the heart to the lungs through a pulmonary artery, and can cause a blockage of blood flow to the lungs. This can result in pulmonary infarction. It can occur from injury to the lower limb, as well as prolonged periods of inactivity such as long flights.
Middle Mediastinum
Where is the heart located (surface projection)?
A: The superior border of the heart corresponds to a line connecting the 2nd left costal cartilage to the 3rd right costal cartilage. The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage. The inferior border corresponds to a line from the 6th right costal cartilage to the 5th left intercostal space at the midclavicular line. The left border corresponds to a line connecting the left inferior border to the left superior border
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What are the spatial relationships of chambers?
A: The right atrium forms the right border of the heart. The right ventricle forms the largest part of the anterior surface of the heart, as well as a small part of the diaphragmatic surface and the majority of the inferior border. The left atrium forms most of the base of the heart. The left ventricle forms the apex of the heart, nearly all of its left border, and most of the diaphragmatic surface.
What is the relationship of the heart to the lungs, diaphragm and thoracic wall?
A: The sternocostal aspect of the heart is formed mainly by the right ventricle. The diaphragmatic surface is formed mainly by the left ventricle and partly by the right ventricle. The right pulmonary surface is formed by the right atrium. The left pulmonary surface is formed by the left ventricle.
How do you locate the SA node?
A: Follow the crista terminalis superiorly in the right atrium to its end. Once there, you will find and old man who will instruct you in the ways of the force. After force proficiency is obtained, purchase an anatomy book and locate the SA node. The AV node is located on the floor of the right atrium next to the interventricular septum.
How is the heart innervated?
A: Sympathetic innervation comes from spinal preganglionic fibers exiting the spinal cord at T1-T4. These can either 1) synapse in the local chain ganglion and the postganglionic fibers will proceed to the cardiac plexus or 2) may ascend in the sympathetic trunk, synapse in the inferior (stellate), middle, and superior cervical ganglia and descend to the cardiac plexus as the inferior, middle, and superior cardiac splanchnic nerves. Parasympathetic innervation of the heart is supplied by the vagus nerve. The vagus nerve exits the skull through the jugular foramen and carries preganglionic fibers through the carotid sheath (anterior to the arch of the aorta on the left and posterior on the right) and synapses with postganglionic cells located within the external surface of the heart (visceral and pericardium). The cardiac plexus therefore receives its preganglionic sympathetic innervation from spinal nerves T1-T4, and postganglionic from the superior, middle, and inferior cardiac nerves. The parasympathetic innervation is supplied by preganglionics from the vagus nerve.
What are the vertebral levels of origin of the sympathetic innervation of the heart?
A: T1-T4
Specifically how are heart rate and contractility controlled?
A: The sinuatrial node controls heart rate, while the atrioventricular node controls contractility.
Where is referred pain from the heart perceived? Where are cell bodies located?
A: The pain afferents travel with the sympathetic innervation. Thus pain is felt in the T1-T4 dermatomes.
What are the typical branches of the right and left coronary arteries?
A: The right coronary artery gives rise to the SA nodal branch, the right marginal branch, and the posterior interventricular branch. The left coronary artery gives rise to the SA nodal branch (sometimes), the anterior interventricular (LAD), and the circumflex branch.
What is a typical case scenario for mitral valve regurgitation?
A: Mitral valve regurgitation often occurs after long nights of binge drinking. This is also the most commonly damaged valve in raptor fights, and mitral valve prolapse occurs in 1/20 people.
What is a typical case scenario for aortic valve incompetence?
A: Most often presents with a collapsing pulse, or a characteristically high pulse pressure (the difference between the systolic and diastolic BP).
Where does one position the stethoscope to best auscultate each of the 4 valves?
A: The aortic valve is best heard in the left 2nd intercostal space. The pulmonary valve is best heard in the right 2nd intercostal space. The tricuspid valve is best heard in the right 5th intercostal space, and the mitral valve is best heard at the apex of the heart.
Superior Mediastinum
What is the AP order of structures in the superior mediastinum?
A: Thymus, brachiocephalic veins and the superior vena cava, arch of the aorta and it’s branches, phrenic nerves, vagus nerves, left recurrent laryngeal nerve, cardiac plexus, trachea, esophagus, thoracic duct.
What are the relationships of the phrenic and vagus nerves?
A: Phrenic nerve descends lateral and anterior to the vagus nerve. This is greatly enjoyed by the vagus nerve.
What nerve curves under the arch of the aorta?
A: The left recurrent laryngeal nerve.
Posterior Mediastinum
What is the order of vessels leaving the arch of the aorta (R-L, A-P)?
A: Brachiocephalic trunk, left common carotid artery, left subclavian artery, posterior intercostal arteries, bronchial arteries, esophageal arteries, and the superior phrenic arteries.
What is the origin of the bronchial and esophageal arteries?
A: Most commonly the aorta(itself having been forged in the fires of mount doom), although the right bronchial arteries often arise from a right posterior intercostal artery.
What lies posterior to the esophagus at T5, T7, T9?
A: At T5, the thoracic duct passes posteriorly to the esophagus. The aorta is posterior to the esophagus around the levels of T7-T9.
What innervates the upper, middle and lower third of the esophagus?
A: The upper third is innervated by the vagus nerve, while the lower two thirds are innervated by the esophageal plexus.
What structures constrict the esophagus?
A: The arch of the aorta, the left main bronchus, and the diaphragm.
What does the phrenic nerve innervate and what are its vertebral levels of origin?
A: The phrenic nerve originates from the ventral rami of C3-C5 and innervates the pericardium and the diaphragm.
What happens to the diaphragm if one phrenic nerve is injured?
A: One side of the diaphragm will become paralyzed.
What are the vertebral levels of the origin of the greater, lesser, least splanchnic nerves?
A: The greater splanchnic nerve arises from T5-T9, the lesser splanchnic nerve arises from T10-T11, and the lease splanchnic nerve arises from T12.
What types of afferents travel with the vagus and greater, lesser, least splanchnic nerves?
A: Since the splanchnic nerves are preganglionic sympathetic fibers, visceral pain afferents will travel with them. The vagus nerve will carry reflexive visceral afferents with it, mediating cough and other reactions.
