The Ribcage: Anatomy, Function, and Conditions

The ribcage, or thoracic cage, is a complex framework of bones and cartilage forming the chest. It serves as a protective shield for the thoracic cavity’s contents and provides structural support for the upper body. This bony structure is not rigid; its unique composition allows for the flexibility required for respiratory movements.

Anatomy of the Ribcage

The ribcage consists of 24 ribs arranged in 12 pairs. These ribs are classified based on their anterior attachment. The first seven pairs are known as “true ribs” because they connect directly to the sternum, or breastbone, through their own costal cartilage.

Following the true ribs are the “false ribs,” which include the eighth, ninth, and tenth pairs. These ribs do not attach directly to the sternum. Instead, their costal cartilages connect to the cartilage of the rib directly above them.

The final two pairs, the eleventh and twelfth ribs, are termed “floating ribs.” These ribs are the shortest and do not connect to the sternum at all; their cartilages terminate within the abdominal musculature. Posteriorly, all 12 pairs of ribs articulate with the 12 thoracic vertebrae of the spine.

The sternum is a flat bone located in the anterior midline of the chest, composed of three parts. The uppermost section is the manubrium, which connects to the clavicles and the first two pairs of ribs. The central and largest part is the body of the sternum, which articulates with the costal cartilages of ribs two through seven. The smallest and most inferior part is the xiphoid process.

Connecting the ribs to the sternum is the costal cartilage. This flexible tissue allows the ribcage to expand and contract during breathing.

Functions of the Ribcage

A primary role of the thoracic cage is the protection of internal organs. It forms a bony barrier that shields the heart and lungs. The cage also provides partial protection for organs in the upper abdomen, including the spleen, liver, and the kidneys.

The ribcage is also integral to the process of respiration. During inhalation, the diaphragm contracts and moves downward, while the intercostal muscles between the ribs contract, lifting the ribcage up and outward. This increases the volume of the thoracic cavity, which decreases internal pressure and allows air to flow into the lungs.

Exhalation is a passive process. The diaphragm and intercostal muscles relax, causing the ribcage to lower and decrease the thoracic volume. This increases the pressure within the chest, forcing air out of the lungs. The ribcage also serves as an attachment point for various muscles of the neck, abdomen, and back.

Common Ribcage Conditions

Rib fractures are a common injury, often resulting from direct trauma from falls, accidents, or impacts during contact sports. Symptoms typically include sharp pain that worsens with deep breaths, coughing, or movement. While many fractures heal on their own, a displaced or broken rib can potentially injure internal organs.

Inflammation of the costal cartilage can lead to a condition called costochondritis. Costochondritis causes localized chest pain and tenderness that can mimic the symptoms of a heart attack, though it is a musculoskeletal issue. The pain may be sharp and is often aggravated by activity or pressure on the affected area.

Another common source of pain in the chest wall is a strain of the intercostal muscles. These are the muscles located in the spaces between the ribs that help with chest wall movement. Overstretching or tearing these muscles, often due to sudden twisting motions or forceful coughing, can cause significant pain and difficulty breathing. It is advisable to seek medical attention for persistent or severe ribcage pain to ensure an accurate diagnosis and appropriate care.