Infrasternal angle

Infrasternal angle (also known as the subcostal angle) is an anatomical term referring to the angle formed by the meeting of the costal margins at the xiphoid process of the sternum. The infrasternal angle can vary in size, but typically ranges from 70 to 90 degrees. It is used in clinical practice to assess the shape and function of the thoracic cage.

Etymology

The term "infrasternal" is derived from the Latin words "infra", meaning "below", and "sternal", referring to the sternum or breastbone. The term "subcostal" is derived from the Latin words "sub", meaning "under", and "costal", referring to the ribs.

Anatomy

The infrasternal angle is formed by the meeting of the lower edges of the rib cage, known as the costal margins, at the xiphoid process of the sternum. The size of the infrasternal angle can vary depending on the shape of the individual's thoracic cage. In a normal, healthy individual, the infrasternal angle typically ranges from 70 to 90 degrees.

Clinical significance

The infrasternal angle is used in clinical practice to assess the shape and function of the thoracic cage. An increased infrasternal angle can indicate a barrel chest, which is often associated with conditions such as chronic obstructive pulmonary disease (COPD) and emphysema. A decreased infrasternal angle can indicate a flat chest, which is often associated with conditions such as pectus excavatum.

Related terms

• Xiphoid process: The lowest part of the sternum, which forms the tip of the infrasternal angle.
• Costal margin: The lower edge of the rib cage, which forms the sides of the infrasternal angle.
• Thoracic cage: The structure of bones that encloses the chest, which includes the ribs, sternum, and thoracic vertebrae.

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