Anatomy of the heart

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Anatomy of the heart

USMLE® Step 1 questions

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Anatomy of the Heart

Figure 1. Anterior view of the heart A with and B without coronary fat and vessels.
Figure 2. Posterior view of the heart A with and B without coronary fat and vessels.
Figure 3. Lateral view of the right atrium of the heart, with A the outer wall of the right atrium dissected and peeled back. B The outer wall of the right atrium not dissected showing the sulcus terminalis.
Figure 4. Outer wall of the right ventricle dissected and peeled back.
Figure 5. Lateral view of the left atrium and left ventricle with the outer walls removed.
Figure 6. Semilunar valves. A Four chamber view of the heart showing the pulmonary and aortic valves. Diagrammatic cross-section of the aortic valve. C Aortic valve and D pulmonary valve.
Figure 7. Four chamber view of the heart showing the conducting system of the heart.


USMLE® Step 1 style questions USMLE

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A 39-year-old man presents to the emergency department for evaluation of chest pain. A chest radiograph is obtained as part of the work-up and shown below:  

Image reproduced from Radiopedia  
Which of the structures represents the aortic arch?  


The heart is a muscular organ just slightly bigger than a person’s loosely clenched fist. It is located in the thorax - more specifically, between the two lungs, in a space called the mediastinum. The heart is covered by a tough membrane called the pericardium, that separates the heart from the other structures in the mediastinum. This position allows the heart to do its job, which is to pump oxygen-rich blood to the entire body, and to send poorly oxygenated blood to the lungs, where gas exchange takes place. The heart is made up of four chambers, and as a whole can be functionally divided into the right heart, made up of the right atrium and the right ventricle, and a left heart, made up of the left atrium and left ventricle. And both atria have pouch-like protrusions called auricles, which can increase their capacity when needed.

Ok, now, poorly oxygenated blood from our bodies and tissues enters the right atrium through the superior vena cava and inferior vena cava. From there, blood passes into the right ventricle, which pumps into the pulmonary trunk, on a voyage towards the lungs and is considered part of the pulmonary circulation. On the other hand, after gas exchange takes place in the lungs, oxygenated blood returns from the lungs through the four pulmonary veins, which drain into the left atrium. Then, oxygenated blood goes in the left ventricle and from there, it’s pumped into the aorta so that it reaches the whole body and is considered part of the systemic circulation.


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  2. "TUMORS, MALIGNANT | Carcinoma, Lymph Node Involvement" Encyclopedia of Respiratory Medicine (2006)
  3. "Hurst's the Heart, 13th Edition: Two Volume Set" McGraw Hill Professional (2010)
  4. "Applied Radiological Anatomy" Cambridge University Press (2012)
  5. "Clinically Oriented Anatomy" Lippincott Williams & Wilkins (2013)
  6. "Braunwald's Heart Disease" Saunders (2004)
  7. "How to determine atrial situs? Considerations initiated by 3 cases of absent spleen with a discordant anatomy between bronchi and atria." Heart (1979)
  8. "Essential Clinical Anatomy" Journal of Anatomy (2007)

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