Chest Wall External Intercostals ORIGIN Inferior border of

Chest Wall

External Intercostals • ORIGIN Inferior border of ribs as far back as posterior angles • INSERTION Superior border of ribs below, passing obliquely downwards and backwards • ACTION Fix intercostal spaces during respiration. Aids forced inspiration by elevating ribs

Internal Intercostals • ORIGIN Inferior border of ribs as far back as posterior angles • INSERTION Superior border of ribs below , passing obliquely downwards and backwards • ACTION Fix intercostal spaces during espiration. Aids forced inspiration by elevating ribs

Diaphragm • Diaphragm • ORIGIN Vertebral: crura from bodies of L 1, 2 (left), L 1 -3 (right). Costal: medial and lateral arcuate ligs, inner aspect of lower six ribs. Sternal: two slips from posterior aspect of xiphoid • INSERTION Central tendon • ACTION Inspiration and assists in raising intra-abdominal pressure

Abdominal Wall

External Oblique • External Oblique • ORIGIN Anterior angles of lower eight ribs • INSERTION Outer anterior half of iliac crest, inguinal lig, public tubercle and crest, and aponeurosis of anterior rectus sheath • ACTION Supports abdominal wall, assists forced expiration, aids raising intraabdominal pressure and, with muscles of opposite side, abducts and rotates trunk

Internal Oblique • Internal Oblique • ORIGIN Lumbar fascia, anterior two thirds of iliac crest and lateral two thirds of inguinal ligament • INSERTION Costal margin, aponeurosis of rectus sheath (anterior and posterior ), conjoint tendon to pubic crest and pectineal line • ACTION Supports abdominal wall, assists forced respiration, aids raising intra-abdominal pressure and, with muscles of other side , abducts and rotates trunk. Conjoint tendon supports posterior wall of inguinal canal

Transverses Abdominis • Transverses Abdominis • ORIGIN Costal margin, lumbar fascia, anterior two thirds of iliac crest and lateral half of inguinal ligament • INSERTION Aponeurosis of posterior and anterior rectus sheath and conjoint tendon to pubic crest and pectineal line • ACTION Supports abdominal wall, aids forced expiration and raising intra-abdominal pressure. Conjoint tendon supports posterior wall of inguinal canal

Rectus Abdominis • ORIGIN Pubic crest and pubic symphysis • INSERTION 5, 6, 7 costal cartilages, medial inferiorcostal margin and posterior aspect of xiphoid • ACTION Flexes trunk, aids forced expiration and raise intraabdominal pressure

QUADRATUS LUMBORUM • Quadratus Lumborum • ORIGIN Inferior border of 12 th rib • INSERTION Apices of transverse processes of L 1 -4, iliolumbar ligament and posterior third of iliac crest • ACTION Fixes 12 th rib during respiration and lateral flexes trunk

Trunk

Iliopsoas • ORIGIN Iliac crest, sacrum, lumbar vertebrae • INSERTION Ribs, cervical transverse processes • ACTION Extends and lateral flexes spine

Erector Spinae • ORIGIN Spinous processes • INSERTION Spinous processes six levels above • ACTION Lateral flexion of spine