Respiration

Muscle	Origin	Insertion	Action
Diaphragm	circular line passing around inner surface wall of body; sternal: xiphoid process; costal: lower 6 ribs on either side; lumbar: L1-L3	Central tendon	draws central tendon down during quiet inspiration
External intercostals	inferior border of upper rib	Superior border of rib below	Draws central tendon down during quiet inspiration
Internal intercostals	Superior border of rib below	Inferior border of rib above	Depresses ribs during expiration
Levatores costarum longi	Transverse process of T7-T10	outer surface of second rib below orgin	Depresses ribs during expiration
Levatores costarum breves	Transverse process of C7-T11	outer surface of rib directly below origin	Elevates rib during inspritation; extends vertebrae; lateral flexion; rotation to opposite side
Serratus posterior superior	Spinous process of C7-T3	Superior borders of second - fifth ribs	Elevates ribs; muscles used in inspiration
Serratus posterior inferior	Spinous process of T11-T12; L1-L3	Inferior borders of lower four ribs	Counteracts pull of diaphragm; aids in respiration
Transversus abdominis	2/3 of inner iliac crest; inner edges of lower six costal cartilages	Linea alba	Constricts abdominal contents; assists in forced expiration
Pyramidalis	Ansterior aspect of symphysis pubis and pubic bone	Linea alba	Compresses abdomen; forced expiration