The ribs are a set of twelve paired bones which form the protective 'cage' of the thorax. They articulate with the vertebral column posteriorly, and terminate anteriorly as cartilage (known as costal cartilage). This bony thorax protects the internal thoracic organs, and also allows for ventilation, as the ribs move during chest expansion to enable lung inflation.
In this article, we shall look at the anatomy of the ribs – their bony landmarks, articulations and clinical correlations.
The typical rib consists of a head, neck and body.
Ribs 1, 2, 10 11 and 12 can be described as ‘atypical’ – they have features that are not common to all the ribs.
The majority of the ribs have an anterior and posterior articulation.
All the twelve ribs articulate posteriorly with the vertebra of the spine. Each rib forms two joints-
The anterior attachment of the ribs vary-
Rib fractures most commonly occur in the middle ribs, as a consequence of crushing injuries or direct trauma. A common complication of a rib fracture is further soft tissue injury from the broken fragments. Structures most at risk of damage are the lungs, spleen or diaphragm.
If two or more fractures occur in two or more adjacent ribs, the affected area is no longer under control of the thoracic muscles. It displays a paradoxical movement during lung inflation and deflation. This condition is known as flail chest. It impairs full expansion of the ribcage, thus affecting the oxygen content of the blood. Flail chest is treated by fixing the affected ribs, preventing their paradoxical movement.
The ribs form an important part of the anatomy of the human body, protecting the thoracic cavity and its vital organs. The anatomy of the rib includes two main components: the head and the body. The head of the rib has two facets: one articulating with the corresponding vertebra, and the other with the vertebra above the head. This often roughened tubercle on the neck of the rib is also known as the costotransverse joint. The body, also known as the shaft of the rib, is flat and curved. It contains a smooth internal groove that provides a neurovascular supply to the thorax, protecting the vessels and nerves from injury or damage.
Of the twelve ribs found in the thorax, ribs 1-7 are considered “typical” in that they attach to the sternum independently. Ribs 8-10 attach to the costal cartilage superior to them, while 11 and 12, often referred to as “floating ribs”, lack an anterior attachment and instead terminate in the abdominal musculature. Of the twelve ribs, ribs 1, 2, 10, 11, and 12 contain atypical features. Rib 1, for example, is shorter and wider than the other ribs, and has only one facet for articulation with its corresponding vertebra. Rib 2 is thinner and longer than rib 1, and has two facets for articulation with its corresponding vertebra. In addition, the superior surface of rib 2 is roughened, from which the serratus anterior muscle originates. Rib 10 only has one facet and ribs 11 and 12 lack a neck, with only one facet for articulation with their corresponding vertebra.
The majority of the ribs have an anterior and posterior articulation. Posteriorly, all twelve ribs articulate with the vertebrae of the spine. Each rib forms two joints – the costotransverse joint, between the tubercle of the rib and the transverse costal facet of the corresponding vertebra, and the costovertebral joint, between the head of the rib, the superior costal facet of the corresponding vertebra, and the inferior costal facet of the vertebra above. Anteriorly, ribs 1-7 attach to the sternum independently, while ribs 8-10 attach to the costal cartilage superior to them, and ribs 11 and 12 lack an anterior attachment.
Rib fractures are a common clinical entity and can have a variety of complications due to their proximity to vital organs. It is important for healthcare providers to understand the anatomy of the rib, in particular the various facets, costal cartilages, and nerves that can be injured in the event of a rib fracture.
