The thoracic cavity is enclosed by twelve pairs of bones called ribs that are joined together in the front by the sternum (breast bone). This set of ribs (rib cage) is attached at the back to another set of small irregular-shaped bones called spinal column (spine).
The thoracic cavity contains major organs and blood vessels. These include the heart, lungs, passageway for food from the mouth to the stomach (oesophagus), the middle and lower airways (tracheobronchial tree), the vessels that carry blood between the lungs and the heart, the large artery that carries blood from the heart to other parts of the body and major veins that transport blood from the body to the heart. It also includes one of the organs of the immune system, the thymus.
- Ribs. Protects the major organs such as heart and lungs and some large blood vessels in the thoracic cavity.
- Sternum (Breast Bone). Protects the heart and holds the ribs in place at the front.
- Spinal or Vertebral Column (Spine). Protects the spinal cord and it is where the ribs meet at the back and completes the rib cage
- Heart. It is located in between the lungs just behind the breastbone in the centre of the thoracic cavity. It supplies blood to all parts of the body. The heart is composed of two upper chambers called atria and two lower chambers called ventricles. The upper chambers are responsible for carrying blood from the heart to the lungs to be oxygenated while the lower chambers are responsible for carrying oxygenated blood to the body.
- Heart valves. There are 4 one-way valves in the heart that allow blood to flow forwards through the chambers and into arteries arising from the heart but prevent blood leaking backwards into the chambers of the heart.The valve between the right atrium and the right ventricle is called the tricuspid valve and the valve from the right ventricle to the pulmonary artery is called the pulmonary valve. A valve is also positioned between the left atrium and left ventricle; this is called the mitral valve. Another valve is located between the left ventricle and the aorta and is called the aortic valve.
- Superior vena cava and inferior vena cava. Large veins that return blue (deoxygenated) blood from the body to the heart.
- Pulmonary artery. A large blood vessel that transports deoxygenated blood from the right ventricle to the lungs.
- Pulmonary vein. A blood vessel that transports oxygenated (red) blood from the lungs to the left side of the heart.
- Aorta. The largest artery that carries oxygenated blood from the heart to all parts of the body.
- Lungs. Essential organs located on either side of the thoracic cavity where the exchange of gases occurs. The lungs receive oxygen from the environment and transfer it into the blood and remove carbon dioxide from blood then release it to the environment.
- Tracheobronchial tree. The central and lower airways that allow air to pass from the nose or mouth to the lungs. It consists of trachea (the airway tube in the middle) and branches out to the left and right bronchi (the airway tubes that go into the left and right lungs) which further branch into smaller airway tubes called bronchioles.
- Oesophagus. Is a tube forming part of the digestive tract where food passes through from the mouth and pharynx to the stomach.
- Thymus. A special organ of the immune system that assists in immune cell maturation.