Which type of muscles are mainly engaged during forced inspiration?

During forced inspiration, the engagement of muscles is crucial for expanding the thoracic cavity beyond normal tidal breathing. Accessory muscles play a significant role in this process. These muscles include the sternocleidomastoid, scalene muscles, and pectoralis major and minor, which assist in elevating the ribs and sternum, thereby increasing the volume of the thoracic cavity and allowing for a greater intake of air.

Although the diaphragm is the primary muscle responsible for normal inhalation, its involvement in forced inspiration is complemented by these accessory muscles to facilitate increased airflow. Skeletal muscles, while essential for respiration, are not specific to forced inspiration, as they generally refer to the muscle tissue type rather than a specific functional group engaged during this phase. Abdominal muscles are primarily used during forced expiration rather than inspiration, as they help expel air from the lungs by increasing abdominal pressure and pushing the diaphragm upwards.

Consequently, the engagement of accessory muscles during forced inspiration is vital for overcoming resistance and enhancing respiratory capability.