Pectoralis Major
Origin: Clavicular head - anterior surface of medial half of clavicle; anterior surface of sternum; aponeurosis of external oblique muscles
Insertion: Lateral lip of inter tubercular sulcus of humerus
Action: Prime mover of arm flexion; adducts, medially
Pectoralis Minor
Origin: Anterior surface of 3rd, 4th, and 5th near their costal cartilages
Insertion: Coracoid process of scapula
Action: Stabilizes scapula by drawing it inferiorly and anteriorly against the thoracic wall. Draws rib cage superiorly.
Deltoid
Origin: Lateral 1/3 of clavicle; acromion and spine of scapula
Insertion: Deltoid tuberosity of humerus
Action: Acting as a whole, prime mover of arm abduction
Serrates Anterior
Origin: Lateral aspect of ribs 1-8 (or 9)
Insertion: Vertebral border of anterior surface of scapula
Action: Prime mover to protract and hold scapula against chest wall; rotates scapula
Subscapularis
Origin: subscapular fossa
Insertion: lesser tubercle of humerus
Action: rotates humerus; stabilizes shoulder
External Intercostals
Origin: Inferior border of rib
Insertion: Superior border of rib
Action: Pulls ribs toward one another to elevate rib cage
Internal Intercostals
Origin: Superior border of rib
Insertion: Inferior border of rib
Action: Draw ribs together to depress rib cage
Diaphragm
Origin: Inferior border of rib and sternum, costal cartilages of last six ribs and lumbar vertebrae
Insertion: Central tendon
Action: Prime mover of inspiration flattens on contraction
Rectus Abdominus
Origin: Pubic crest and symphysis
Insertion: Xiphoid process and costal cartilages of ribs 5-7
Action: Flexes and routes vertebral column
External Oblique
Origin: Anterior surface of last eight ribs
Insertion: Linea alba, pubic crest and tubercles, and iliac crest.
Action: Compresses abdominal wall; trunk rotation and lateral flexion.
Internal Oblique
Origin: Lumber fascia, iliac crest, and inguinal ligament.
Insertion: Linea alba, pubic crest and costal cartilages of last three ribs
Action: As for external oblique
Transverses Abdominus
Origin: inguinal ligament, iliac crest, cartilages of last five or six ribs, and lumbar fascia
Insertion: linea alba and pubic crest
Action: Compresses abdominal contents.
Linea Alba