During inspiration, which muscle is primarily responsible for elevating or stabilizing the clavicle?

During inspiration, which muscle is primarily responsible for elevating or stabilizing the clavicle?

• A. Scalene muscle
• B. Diaphragm
• C. Rectus abdominis
• D. Intercostal muscles

Answer: (A)

During inspiration, the body uses accessory muscles to expand the upper chest. The scalene muscles attach to the cervical spine and insert on the first two ribs, so when they contract they elevate those ribs and help stabilize the upper thorax near the clavicle. This action supports clavicular position and contributes to thoracic expansion, especially in deeper or labored breathing. The diaphragm mainly lowers the thoracic cavity to increase vertical volume, intercostal muscles move the ribs but don’t specifically elevate the clavicle, and the rectus abdominis is involved in expiration and trunk flexion.

During inspiration, the body uses accessory muscles to expand the upper chest. The scalene muscles attach to the cervical spine and insert on the first two ribs, so when they contract they elevate those ribs and help stabilize the upper thorax near the clavicle. This action supports clavicular position and contributes to thoracic expansion, especially in deeper or labored breathing. The diaphragm mainly lowers the thoracic cavity to increase vertical volume, intercostal muscles move the ribs but don’t specifically elevate the clavicle, and the rectus abdominis is involved in expiration and trunk flexion.