Major Muscles of Respiration
Diaphragm
Flattens during contraction, which expands thoracic cavity and compresses abdominal viscera during inspiration origin - ribs 7-12, xiphoid and lumbar vert insertion - central tendon of diaphragm
Internal intercostals
depresses ribs, which compresses thoracic cavity during forced expiration origin - superior border of inferior rib insertion - inferior border of superior rib
major muscles of inspiration
diaphragm and external intercostals
External intercostals
elevates ribs, which expands thoracic cavity during inspiration origin - inferior border of superior rib insertion - superior border of inferior rib
primary muscle for forced expiration
internal intercostals
accessory muscles in respiration
sternocleidomastoid scalenes pectoralis minor rectus abdominis external obliqu