GROSS ANATOMY

Detailed explanation-1: -Action: diaphragm is the main inspiratory muscle, during inspiration it contracts and moves in an inferior direction that increases the vertical diameter of the thoracic cavity and produces lung expansion, in turn, the air is drawn in.

Detailed explanation-2: -When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. The muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale.

Detailed explanation-3: -The external intercostal muscles connect the ribs in such a way that the contraction of the muscles lifts the ribs and rib cage and expands the anterior–posterior dimensions of the rib cage.

Detailed explanation-4: -Sets 11 and 12 are floating ribs, and they only connect to the thoracic vertebrae of the spinal column in the back. It is the flexible costal cartilage that allows the ribs to expand when people take deep breaths.

Detailed explanation-5: -The costal cartilages are bars of hyaline cartilage that serve to prolong the ribs forward and contribute to the elasticity of the walls of the thorax. Costal cartilage is only found at the anterior ends of the ribs, providing medial extension.