<prompt> Main inspiratory muscle is ?Lattissimus dorsiTransversus thoracisSerratus anteriorDiaphragm  <response>: Respiratory muscles Inspiratory muscles1. During quiet breathing : Diaphragm most impoant, external intercostal and interchondral pa of internal intercostal.2. During forced inspiration : Sternocleidomastoid, serratus anterior, serratus posterior superior, pectoralis major and minor, erector spinae, scaleni and levator costarum.Expiratory muscles1. During quiet breathing : Passive process due to passive recoil of the lungs and thoracic wall.2. During forced expiration : Internal intercostal, innermost intercostal, transversus thoracic, serratus posterior inferior, subcostalis, lattissimus dorsi and abdominal muscles rectus abdominis, internal and external oblique and transversus abdominis. 