Muscles involved in respiration

Internal Oblique

Middle of three muscles that form the anterolateral abdominal wall Compresses the abdominal wall during expiration

Rectus Abdominus

Most external of the three muscles that form the anterolateral abdominal wall Extends from xiphoid process to the symphysis pubis Compresses abdominal wall during expiration

Pectoralis Major

Muscle that is deep to the pectoralis major on the upper ribs Origin: Coracoid process of scapula Insertion: 3,4,5th ribs Elevates ribs during inspiratio

Internal Intercostals

Occupies deep intercostal space Origin: superior margin of inferior rib Insertion: superior margin of inferior rib Muscle that depresses the ribs in expiration

External Intercostals

Occupies superficial intercoastal space Origin: inferior margin of superior rib Insertion: superior margin of inferior rib Elevates ribs during inspiration

External Oblique

Compresess the abdominal wall during expiration

Serratus Anterior

Covers superior and lateral surface of the rib cage Origin: superior 8 or 9 ribs Insertion: vertebral border and inferior angle of scapula Elevates ribs during inspiration

Sternocleidomastodeus

Crosses the neck from the sternum to the mastoid process Origin: mastoid process of temporal bone Insertion: Clavicle and sternum Elevates sternum during inspiration

Transverse Abdominus

Deepest of three muscles that form the anterolateral abdominal wall Compresses the abdominal wall during expiration

Diaphragm

Dome-shaped sheet of muscle and connective tissue that separates the thorax from the abdominal cavity Muscle that is associated with quiet breathing Muscle that moves inferiorly during inspiration Muscle that moves superiorly during expiration