Set 5 Muscles Superficial Power Muscles of the Torso Lumbodorsal Fascia Lumbodorsal fascia Origin: Origin: Insertion: Insertion: Action: Action: coccyx up past T10 point of half diamond ends up around L3-L4 area increases surface area for attachment of large muscles Latissimus dorsi power-stroke muscle Latissimus dorsi Origin: Origin: Insertion: Insertion: Action: Action: Spinous processes of sacral, lumbar and lower thoracic vertebrae (T7- L5); iliac crest (pelvis); lower ribs (9-12) Intertubercular grove of humerus (twist around teres major) (twist around teres major) Powerfully extends and adducts arm and rotates humerus inwardly or pulls shoulder downward and posteriorly Intertubercular groove Pectoralis major pledge of allegiance muscle Pectoralis major: pars abdominalis Origin: Origin: Insertion: Insertion: Action: Action: aponeurosis of external obliques over medial part of ribs 5-7 adducts shoulder, rotates medially and extends (last part of tennis or volleyball serve) lateral ridge of intertubercular groove of humerus Pectoralis major: pars sternocostalis Origin: Origin: Insertion: Insertion: Action: Action: anterior surface of sternum and costal cartilage of ribs 1-7 adducts the arm across chest and pulls shoulder forward (tennis forehand) lateral ridge of intertubercular groove of humerus Pectoralis major: pars clavicularis Origin: Origin: Insertion: Insertion: Action: Action: sternal half of clavicle lateral ridge of intertubercular groove of humerus adducts the arm upward toward the face (last part of bowling or uppercut in boxing) Trapezius: pars spinalis (lower division) sexy shoulder muscle Trapezius pars spinalis (lower division) Origin: Origin: Insertion: Insertion: Action: Action: posterior portion of the spine of scapula Power muscle that pulls scapula back and medially rotates Spinous process of T4-T12 vertebrae Trapezius: pars acromialis (middle division) sexy shoulder muscle Trapezius: pars acromialis (middle division) Origin: Origin: Insertion: Insertion: Action: Action: lower end of the nuchal ligament, spinous processes of C6-T3 vertebrae medial margin of the acromial process and the distal end of the scapular spine Power muscle that lifts the shoulder upward and back Trapezius: pars clavicularis (upper division) sexy shoulder muscle Trapezius: pars clavicularis (upper division) Origin: Origin: Insertion: Insertion: Action: Action: begins at the superior part of nuchal ligament from the occipital bone and continues along the nuchal ligament to C6 vertebrae superior border of the last lateral third of the clavicle elevates scapula and helps rotate arm upward (supports weight of arm) Trapezius sexy shoulder muscle Nuchal Ligament