Sternal Angle

Sternal Angle

The terms 'sternal angle' or 'Angle of Louis' refer to the angle that is formed at the junction of the manubrium and the sternum body. This write-up provides information on the clinical significance of the Angle of Louis.
The sternum, which is also known as the breastbone, is basically an elongated flattened T-shaped bone that is located at the upper middle section of the thoracic region. This bone is divided into the manubrium, sternum body, and the xiphoid process. The manubrium is situated at the upper section of the sternum. Commonly known as the handle, the manubrium is connected to the first two ribs. Sternum body, which is also known as gladiolus, forms the middle section of the sternum. It attaches directly to the third and the seventh ribs. The angle that is formed at the junction of the manubrium and the sternum body is referred to as the sternal angle. It is also referred to as the 'Angle of Louis' and the manubriosternal joint. The xiploid process is the cartilaginous tip that is located at the bottom of this flattened bone. The ribs are connected to the sternum through the costal cartilage. It is an integral part of the thoracic region and serves the vital function of protecting the organs in the thoracic cavity.
Clinical Significance of the Angle of Louis
The angle of Louis is named after a French physician, Pierre Charles Alexandre Louis.

Located at the junction of the manubrium and the body of the sternum, it marks the site wherein the trachea bifurcates into the right and left main bronchi.

It also marks the location of the beginning of the aortic arch.

It is referred to as a clinical landmark, as it is used as a reference for the location of the second pair of the costal cartilages. The protrusion at the anterior thoracic wall also helps in marking some of the structures present in the thoracic region.

It serves as a reference point while counting the ribs. It can be palpated to locate the second pair of ribs, and it also corresponds to the T4/T5 intervertebral disc.
Causes of Pain in and Around the Manubriosternal Joint
While certain medical conditions can cause pain around this angle, trauma to the breastbone is one of the common causes of sternum pain. Fall from a great height, a severe blow to the chest or slamming of chest against the steering wheel in an accident could cause the sternum to fracture and this can cause severe rib pain.
Weightlifting could also cause an immense strain on the rib cage. Those who play contact sports such as boxing or football are at an increased risk of sternum fracture or injuries. Punches on the sternum can cause the ribs to get bruised and this can cause pain around the manubriosternal joint. Trauma to the rib cage could also cause the costosternal joint to get inflamed. This could give rise to a medical condition called costochondritis. Inflammation could also occur due to overuse or injuries.
Costochondritis, Tietze's syndrome or calcification of costal cartilage are some of the medical conditions that could cause the manubriosternal joint to pop. People affected by joint disorders are also susceptible to sternum injuries. If your bones are weak, then a slight injury can also cause complications. If you have been experiencing rib pain or painful breathing, you must consult a doctor soon. It's possible that sternum pain might be caused due to medical conditions associated with the organs located in the thoracic cavity. A physical examination along with a chest X-ray or other imaging procedures can help the doctors determine the cause of the pain around the Angle of Louis.
Sternum is an important part of the rib cage that helps protect the organs in the chest region. If you have been experiencing pain in this region, consult a doctor soon. As with any other health issue, a timely diagnosis and treatment will speed up the recovery process.