Thorax Anatomy Quiz – Pleura, Mediastinum and Chest Organs

All 21 parts on the diagram

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Chest opened 12

Right lung The lung on the body's right, drawn on the left.
Left lung The lung on the body's left, with a notch for the heart.
Trachea The windpipe, which divides into the two main bronchi.
Diaphragm The sheet of muscle under the lungs and heart.
Pericardium The sac that holds the heart, in the middle mediastinum.
Aortic arch The bend of the aorta, in the superior mediastinum.
Superior vena cava The great vein that enters the right side of the heart.
Thymus A two-lobed gland behind the sternum, in front of the heart.
Parietal pleura The pleura that lines the chest wall and the diaphragm.
Pleural cavity The thin space between the two layers of pleura.
Costodiaphragmatic recess The low corner of the pleural cavity, below the lung.
Phrenic nerve The nerve of the diaphragm. It runs down beside the pericardium.

Mediastinum 9

Sternal angle Where manubrium and body of the sternum join. The dividing plane starts here.
Superior mediastinum The part above the sternal angle. It holds the aortic arch.
Middle mediastinum The part that holds the heart in its pericardium.
Anterior mediastinum The narrow part between the sternum and the pericardium.
Posterior mediastinum The part behind the pericardium, in front of the backbone.
Esophagus The food tube, running down the posterior mediastinum.
Descending aorta The aorta below its arch, in the posterior mediastinum.
Thoracic duct The largest lymph vessel. It climbs in front of the backbone.
Azygos vein A vein that climbs beside the backbone to the superior vena cava.

How this list was compiled: Every name, and the part of the mediastinum each structure lies in, checked on 2026-10-01 in both of these. (1) Gray, Anatomy of the Human Body, 20th edition, 1918 (public domain): The Mediastinum, https://www.bartleby.com/107/239.html (the superior mediastinum above a plane from the junction of manubrium and body of the sternum to the fourth thoracic vertebra, holding the aortic arch, trachea, esophagus, thoracic duct and the remains of the thymus; the anterior mediastinum before the pericardium; the middle mediastinum with the heart in the pericardium and the phrenic nerves; the posterior mediastinum with the descending aorta, the azygos vein, the esophagus and the thoracic duct) and The Pleurae, https://www.bartleby.com/107/238.html (the parietal pleura, the pleural cavity, and the slit below the lung, which Gray calls the phrenicocostal sinus). (2) Wikipedia, text only: Mediastinum, Pleural cavity, Costodiaphragmatic recess, Thymus, Phrenic nerve, Thoracic duct, Azygos vein, Pericardium, Thoracic diaphragm and Sternal angle, https://en.wikipedia.org/wiki/Mediastinum and https://en.wikipedia.org/wiki/Pleural_cavity . No OpenStax page was read. Licence: own work

The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work

How it works

A thoracic anatomy quiz on two drawings. First label the structures of the thoracic cavity from the front, then the mediastinum from the side.

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Chest opened

Each lung lies in a pleural sac. The parietal pleura lines the wall and the diaphragm, and the pleural cavity is the thin space inside it. The low outer corner, which the lung does not fill, is the costodiaphragmatic recess. Between the sacs lie the trachea, the thymus, the great vessels and the heart in its pericardium.

Mediastinum

A plane from the sternal angle back to the fourth thoracic vertebra divides it. Above is the superior mediastinum. Below, the anterior part lies in front of the pericardium, the middle part is the pericardium and heart, and the posterior part lies behind, with the esophagus, descending aorta, thoracic duct and azygos vein.

The body's right lung is on the left of the drawing, as if the person faced you.
The pleural cavity and the zones are drawn wide so you can tap them.

Questions and answers

What are the four parts of the mediastinum?

The superior mediastinum, above the level of the sternal angle, and three parts below it: the anterior, in front of the pericardium; the middle, which holds the heart in its pericardium; and the posterior, behind the pericardium.

What is in the posterior mediastinum?

The descending aorta, the esophagus, the thoracic duct and the azygos vein, with the vagus nerves and some lymph nodes.

What is the costodiaphragmatic recess?

The lowest corner of the pleural cavity, where the pleura of the wall meets the pleura of the diaphragm. The lower edge of the lung does not reach down into it.

What are the structures of the thoracic cavity?

Two pleural sacs, each with a lung, and between them the mediastinum, which holds the heart in its pericardium, the great vessels, the trachea, the esophagus, the thymus and the thoracic duct.