| Muscle | Origin and Insertion | Action |
| External Oblique | (O) Outer surfaces of lower 8 ribs
(I) Linea alba; anterior half of iliac crest | Flexes laterally; Flexes and rotates trunk; compresses abdomen |
| Infraspinatus | (O) Infraspinus Fossa
(I) Greater tubercle of humerus | Laterally rotates arm |
| Internal oblique | (O) Lumbodorsal fascia, iliac crest and inguinal ligament
(I) Linea alba, pubic crest, last 3 or 4 ribs | Compresses abdomen; flexes and rotates femur |
| Latissimus Dorsi | (O) Spines of vertebrae T7-S5; lower 3-4 ribs and iliac crest
(I) Intertubercle groove of humerus | Extends, adducts and medially rotates arm |
| Pectorials major | (O) Clavicle; sternum; cartilage of ribs 1-6; aponeurosis of external oblique
(I) Greater tubercle of humerus | Flexes, adducts and medially rotates arm |
| Pectoralis Minor | (O) Anterior surface of ribs 3-5
(I) Coracoid Process | Depresses and pulls scapula anterioraly |
| Rectus Abdominus | (O) Pubic crest and symphysis
(I) Xiphoid process, costal cartilages 5-7 | Compresses abdomen; flexes trunk |
| Serratus Anterior | (O) Outer surface of ribs 1-8 (or 9)
(I) Entire anterior surface of vertebral boreder of scapula | Abducts and stabilizes scapula |
| Subscapularis | (O) Subscapular fossa
(I) Lesser tubercle of humerus | Medially rotates arm |
| Supraspinatus | (O) Supraspinous fossa
(I) Greater tubercle of humerus | Abducts arm |
| Teres major | (O) Posterior surface of scapular at inferior angle
(I) Lesser tubercle of humerus | Extends, medially rotates, and adducts arm |
| Teres minor | (O) Axillary border of scapula
(I) Greater tubercle of humerus | Laterally rotates arm |
| Transverse Abdominis | (O) Inguinal ligament; lumbodorsal fascia; costal cartilages of lower ribs; iliac crest
(I) Linea Alba; pubic crest | Compresses abdomen |
| Trapezius | (O) Occipital bone; ligimentumnuchae spines of vertebrae C7-T12
(I) Acromion and spine of scapula; Lateral third of clavicle | Elevates, depresses, rotates, adducts and stabalizes scapula |
| External intercoastals | (O) Inferior border of rib above
(I) Superior border of rib below | Draws ribs together |
