The thorax is the superior part of the trunk extending between the neck and the abdomen. It consists of several components:

• Thoracic wall
• Several cavities
• Nerves, blood vessels, lymphatics
• Internal organs
• Breasts

Thoracic wall

The thoracic wall consists mainly of muscles and bones that form the thoracic cage. Overall, the thoracic wall is formed by the following structures:

• Anteriorly - sternum; also called the breastbone; it is located in the anterior midline of the thorax and consists of three parts;
• Laterally - twelve ribs on each side and three layers of intercostal muscles; intercostal muscles fill the intercostal spaces between adjacent ribs; each intercostal space has three different intercostal muscles - external, internal and innermost intercostal muscles; these muscles move the ribs and provide mechanical support for the intercostal spaces and thoracic wall;
• Posteriorly - twelve thoracic vertebrae (read more!) and their intervertebral discs.