Anatomy clinical correlates: Thoracic wall

If it wasn't for our thoracic wall, many of the important organs in our thoracic cavity would be unprotected and vulnerable to injury.

But sometimes the thoracic wall itself can be injured, which has a wide range of clinical consequences depending on the affected structures.

Let’s start by talking about the ribs.

First, like any other bone in our body, ribs can break, causing rib fractures.

These usually result from direct trauma or crushing injuries.

The middle ribs are the ones most commonly fractured.

The weakest part of a rib is the posterolateral bend, anterior to its angle.

However, direct trauma can cause a rib to fracture anywhere.

The broken part of the rib can harm internal organs, such as the liver, kidney or the spleen.

Rib fractures higher up can cause mediastinal injuries, and if the fracture is lower, then it can tear the diaphragm.

Furthermore, rib fractures at any level have the risk of causing an intrathoracic injury such as a pneumothorax, which is when there’s air in the pleural cavity, and that doesn’t allow the lung on that side to expand properly.

Since ribs move during respiration, coughing, laughing and sneezing are very painful after a rib fracture!

A related injury is a flail chest, which is when three or more ribs fracture in two or more places, which can allow a big segment of the thoracic wall to move freely.

During a normal inspiration, the thoracic wall expands outwards and increases its diameter, whereas during expiration, it decreases its diameter to expel air.

However, when there’s a flail chest, the movement is paradoxical, meaning that during inspiration, the free segment actually moves inward and during expiration, it moves outward.

This is an extremely painful injury that impairs ventilation, and, as a consequence, blood isn’t properly oxygenated.

Management wise, for a flail chest, you want to ensure adequate pain control and supplemental oxygen if needed.

If respiratory failure occurs as a result of the flail chest, then positive pressure ventilation can be used to force the flail chest segment out during inspiration.

Sometimes, a chest tube may also be required.

Now, between the ribs, in the anterior part of the chest, there’s the sternum, which is the protector of the mediastinal viscera.