← ModulesModule 3 · CardiovascularFrançais

Lesson 1 · Explore → explain → apply

The heart in the chest

Read the short notes, then explore the diagrams or 3D models. Follow a pathway and explain it in your own words before trying the questions.

The heart sits between the lungs, in a space called the middle mediastinum. The pericardium is the protective sac around it. Most of the heart lies slightly left of the body’s midline.

Use nearby structures to orient yourself. The sternum, or breastbone, is in front of the heart. The oesophagus and descending thoracic aorta are behind it.

The apex is the pointed tip of the heart. It is formed by the left ventricle and points down, forward and left. The broad base faces mainly backward and is formed mostly by the left atrium.

The apex usually lies near the fifth left intercostal space, between ribs five and six, on the midclavicular line. This imaginary vertical line passes through the middle of the collarbone.

The tough outer pericardium attaches to the central tendon of the diaphragm, the main breathing muscle. This attachment helps explain why the heart moves with the diaphragm.

Before exploring a diagram, find its front and back. In both the front view and the cross-section viewed from below, the patient’s right appears on your left. Use the orientation marker to check.

Anterior relationships

Reduced motion · use the slider to explore each state.

Sternum0%
Anterior relationshipsSternum: Anterior to the heart; the lungs lie on either side. Apex: Left ventricular tip, directed down, forward and left. Left lung: The cardiac notch accommodates the leftward heart projection. Diaphragm: The fibrous pericardium attaches to its central tendon. Great vessels: The aorta, pulmonary vessels and venae cavae connect at the heart’s superior region.Patient RPatient L1Sternum2Apex3Left lung4Diaphragm5Great vessels
Explore the anatomy · 1

Sternum

About this part

Anterior to the heart; the lungs lie on either side.

What it does

The sternum helps protect the heart and major vessels. It anchors the ribs through their costal cartilages, forming the front of the rib cage.

Sternum

Anterior to the heart; the lungs lie on either side.

Educational sequence · slowed and simplified, not real-time physiology · Guided landmark tour

Transverse section · viewed from below

Reduced motion · use the slider to explore each state.

Sternum · anterior0%
Transverse section · viewed from belowSternum · anterior: Use this landmark to orient the section. Vertebra · posterior: The vertebral body lies behind the mediastinum. Heart in the mediastinum: The heart occupies the middle mediastinum between the lungs. Oesophagus: Posterior to the left atrium. Descending aorta: Posterior and to the patient’s left of the oesophagus in this schematic.Patient RPatient L1Sternum · anterior2Vertebra · posterior3Heart in the mediastinum4Oesophagus5Descending aorta
Explore the anatomy · 1

Sternum · anterior

About this part

Use this landmark to orient the section.

What it does

Protects structures in the chest and anchors the rib cage anteriorly.

Sternum · anterior

Use this landmark to orient the section.

Educational sequence · slowed and simplified, not real-time physiology · Guided landmark tour

Demonstrate your understanding

Six questions. One complete attempt.

Answer all six correctly in one attempt to unlock the next lesson. Submit first, then review explanations. If you miss a question, revisit the illustrations and try the full check again.

Attempt 1 · 0 / 6 answered

01Where is the heart located?
02Which chamber forms the apex?
03Which structure lies anterior to the heart?
04In a section viewed from below, where is the patient’s right?
05Where would you look for the usual apex projection?
06Which relationship explains the heart moving with the diaphragm?

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Learning references and illustration notes

Original teaching diagrams based on the supplied reference topics. Anatomy and bilingual expert review pending. These local practice gates are not a clinical competency certification.