Which muscles are primarily involved in inspiration?

The muscles primarily involved in inspiration play a critical role in the mechanics of breathing, allowing air to enter the lungs. Among these, the external intercostal muscles and the diaphragm are the key contributors.

The diaphragm is a dome-shaped muscle located beneath the lungs, and its contraction is the primary driver of inspiration. When the diaphragm contracts, it flattens and moves downward, increasing the thoracic cavity's volume and creating a negative pressure that draws air into the lungs.

The external intercostal muscles assist this process by elevating the ribs, which further increases the thoracic cavity's volume. Although both the diaphragm and external intercostals contribute significantly to the mechanics of breathing, the diaphragm is considered the most crucial muscle for inhalation.

The internal intercostals primarily assist with expiration, particularly during forceful breathing, while the abdominal muscles are mainly involved in expiration and do not play a primary role in the process of inspiration.

Thus, the option referencing the external intercostals is indeed relevant to the process of inhalation, but it's essential to recognize that the diaphragm is the primary muscle responsible for initiating inspiration.