what are the structures used in inhalation and exhalation?

The muscle that control Inhating and Exhaling do so by changing the volume of the thoracic cavity which is where the Lungs are. During passive respiration there is only one muscle involved, the Thoracic Diaphragn (more commonly reffered to the diaphragm) which is a sheet muscle that covers most of the bottom of the thorax by attaching around the bottom of the ribs. When relaxed the diaphragm us curved upwards into the throax and when contracted it pulls down to a flatter shape sucking air in. The only force drivingthe air out again during expiration is the elasticity of the lungs themselves which shrink the lung volume pushing air out. During Forced Respiration the intercostals muscles also take part. These are the muscles between the ribs and and change thoracic volume by either lifting or depressing the Rib Cage. There are three layers of intercostal muscles; the External Intercostals which elevate the rib cage up and out drawing in; the Internal Intercostals wich depress the rib cage down and in pushing air out; and the Innermost Intercostals which assist the internal intercostals.