Thoracic wall


The thoracic wall or chest wall is the boundary of the thoracic cavity.

Structure

The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae.
The chest wall has 10 layers, namely skin, superficial fascia, deep fascia and the invested extrinsic muscles, intrinsic muscles associated with the ribs, endothoracic fascia and parietal pleura. However, the extrinsic muscular layers vary according to the region of the chest wall. For example, the front and back sides may include attachments of large upper limb muscles like pectoralis major or latissimus dorsi, while the sides only have serratus anterior.The thoracic wall consists of a bony framework that is held together by twelve thoracic vertebrae posteriorly which give rise to ribs that encircle the lateral and anterior thoracic cavity. The first nine ribs curve around the lateral thoracic wall and connect to the manubrium and sternum.

Function

Diving reflex

When not breathing for long and dangerous periods of time in cold water, a person's body undergoes great temporary changes to try to prevent death. It achieves this through the activation of the mammalian diving reflex, which has three main properties. Other than bradycardia and peripheral vasoconstriction, there is a blood shift which occurs only during very deep dives that affects the thoracic cavity. When this happens, organ and circulatory walls allow plasma/water to pass freely throughout the thoracic cavity, so its pressure stays constant and the organs are not crushed. In this stage, the lungs' alveoli fill up with blood plasma, which is reabsorbed when the organism leaves the pressurized environment. This stage of the diving reflex has been observed in humans during extremely deep free dives.

Clinical significance

In rare cases, intentional or accidental, trauma may lead to chest wall necrosis.