The external intercostals are located in the intercostal spaces between the ribs, forming part of the muscles associated with the thoracic cage. They are relatively thin muscles that run obliquely between adjacent ribs.

Origin:
Originating from the inferior border of the rib above, the external intercostals take their starting point from the lower margin of each rib.

Insertion:
The muscles insert into the superior border of the rib below, extending along the length of each intercostal space. This insertion site establishes a connection with the upper margin of each adjacent rib.

Function:
Functionally, the external intercostals play a crucial role in the mechanics of breathing. During inhalation, these muscles contract, causing the ribcage to expand. This expansion contributes to an increase in the thoracic volume, facilitating the intake of air into the lungs. The external intercostals are particularly active during forced inhalation or during activities that require increased respiratory effort. Their contraction elevates the ribs and assists in creating a negative pressure in the thoracic cavity, allowing air to flow into the lungs. The external intercostals are vital components of the respiratory system, contributing to the rhythmic process of breathing.

The external intercostals are muscles located between the ribs that assist with expansion of the rib cage during inhalation. They play an important role in breathing mechanics and help support respiration during exercise and physical activity.

The external intercostals work together with the diaphragm and other respiratory muscles to improve breathing efficiency and maintain oxygen delivery during movement.

Application to Exercise Performance
The external intercostals contribute to:
Rib cage expansion during breathing
Improved breathing efficiency during exercise
Respiratory support during cardiovascular and resistance training
Maintenance of proper breathing mechanics during movement