kylkivälilihakas

The kylkivälilihakas, also known as the lateral intercostal muscle, is a muscle located in the intercostal spaces of the thoracic cavity. These muscles lie between the ribs, running obliquely downwards and forwards from the rib above to the rib below. They are part of the larger group of intercostal muscles, which play a crucial role in respiration.

The kylkivälilihakas acts primarily as an accessory muscle of inspiration, meaning it assists in breathing, particularly during forceful inhalation. When these muscles contract, they pull the ribs upwards and outwards, expanding the thoracic cage. This increase in volume decreases the pressure within the lungs, allowing air to rush in. While the external intercostal muscles are the primary muscles of inspiration, the kylkivälilihakas contributes to this process.

During exhalation, the kylkivälilihakas relaxes, allowing the ribs to move downwards and inwards, decreasing the thoracic volume and forcing air out of the lungs. This action is passive during normal, quiet breathing but can become active during forced exhalation, working in conjunction with other expiratory muscles. The precise contribution of the kylkivälilihakas compared to other intercostal muscles is a subject of ongoing physiological study.