kylkiluulihakset

Kylkiluulihakset, commonly referred to as intercostal muscles, are a group of muscles located between the ribs. These muscles play a crucial role in the mechanics of breathing. They are divided into two main groups: external intercostals and internal intercostals, with a third, innermost intercostal layer also described.

The external intercostal muscles are located on the outer surface of the rib cage. During inhalation, they contract, pulling the ribs upward and outward. This action increases the volume of the thoracic cavity, leading to a decrease in pressure and the drawing of air into the lungs.

The internal intercostal muscles are situated beneath the external intercostals. Their primary function is in forced exhalation. When these muscles contract, they pull the ribs downward and inward, reducing the volume of the thoracic cavity and expelling air from the lungs with greater force than passive exhalation.

The innermost intercostals are a deeper layer, and their exact function is debated, though they are thought to contribute to both inspiration and expiration, similar to the external and internal intercostals respectively, but with less force. Together, these muscles form a complex system that allows for the rhythmic and efficient process of respiration. They are essential for both quiet, resting breathing and for the increased respiratory demands during physical activity or respiratory distress.