Costal margin forms the connection between the 7th pair of ribs and the first three pairs of false ribs. Because the margin reinforces the stability of the false ribs, it allows them to protect the vital organs that rest within the chest cavity. The costal margin also enables the false ribs to support the overall function of the ribcage especially in the breathing process. That is why any problems related to this connective tissue can be felt by the entire chest.
The right costal margin is the lower right side of the thorax (chest) formed by the lower edge of the ribcage while the left costal margin is located correspondingly.
The location of the costal margin is an important factor in medical diagnosis. Pain or tenderness on the margin, as well as on the surrounding areas points to some underlying health problems. Moreover, the margin’s location is a crucial area for inspection before conducting surgical procedures on the chest or abdomen.
What is the function of the costal margin?
The Costal margin plays an important role in the overall structure of the chest cavity. The rib cage shapes the chest cavity and is composed of 12 pairs of bones. This bony upper body structure houses a number of important organs like the heart and lungs. Parts of the liver and stomach can be found here too. The rib cage acts as a protective barrier for these organs. It also aids in the breathing process.
There are three types of ribs and these are:
- True ribs
True ribs refer to the ribs that are directly connected to the breastbone and these are the 1st to 7th pair of ribs.
- False ribs
False ribs are the bones which are indirectly connected to the breastbone, and these are the 8th to 10th pair of ribs. These ribs are adjoined to the cartilage of the 7th rib pair by means of the costal margin.
- Floating ribs
Floating ribs are part of false ribs but are floating because they are not connected to the breastbone or ribs. These ribs are directly connected to the spine and comprise the 11th and 12th pair of ribs in the rib cage.
How to locate costal margin?
The Costal margin can be located on the lowest part of the costal angle. This angle marks the two sides of costal cartilage which forms a triangular space on the lowest part of the chest cavity. People can even sense the margin by tracing the skin surface starting from the lowest part of the breastbone down to side of the chest. The location of the margin is important not only during medical evaluations involving pain or tenderness in this area but during surgical procedures that will expose the abdomen and chest.
What does costal margin pain signify?
Pain on the Costal margin generally indicates an underlying health problem. It could signify problems in the ribs, vital organs resting within or from the margin itself. The margin is usually tender to touch. The most common condition related to tenderness and pain along this area is Rib-tip syndrome or painful rib syndrome. The doctor usually conducts a hook maneuver test to diagnose costal margin pain and may recommend anesthetizing the irritated inter-costal nerve. Severe cases of this syndrome may require resection of the rib tip.