Pectoral Girdle Muscles Origin, Insertion, Action and Innervation
Deltoid
O: Clavicle, acromion process and spine of scapula I: Deltoid tuberosity of humerus A: Anterior fibers: flexion, medial rotation of humerus lateral fibers: abduction of humerus posterior fibers: extension and lateral rotation of humerus andterior and posterior together: adduction of humerus Innervation: axillary nerve
pectoralis major
O: clavicle, sternum and costal cartilages of true ribs I: greater tubercle of humerus A: flexion, adduction, medial rotation of humerus Innervation: medial and lateral anterior thoracic nerves
Trapezius
O: Occipital bone, nuchal ligament, spinous process C7-T12 I: Clavicle, acromion and spine of scapula A: all fibers: adduct scapula superior fibers: elevate shoulder, turn head and extend neck Middle fibers: adduct scapula Inferior fibers: depress scapula Innervation: spinal accessory nerve (cranial nerve #XI)
Infraspinatus
O: infraspinous fossa of scapula I: Greater tubercle of humerus A: lateral rotation of humerus Innervation: suprascapular nerve 1 of the 4 rotator cuff muscles
Teres Minor
O: lateral (axillary) border of scapula ABOVE inferior angle I: greater tubercle of humerus A: lateral rotation of humerus Innervation: axillary nerve 1 of 4 of the rotator cuff muscles
Teres Major
O: lateral (axillary) border of scapula AT inferior angle I: medial lip of intertubercular groove of humerus A: medial rotation of humerus and assists with extension and adduction of humerus Innervation: lower subscapular nerve
Subscapularis
O: medial portion of subscapular fossa I: lesser tubercle of humerus A: medial rotation of humerus Innervation: subscapular nerve 1 of the 4 rotator cuff muscles
Rhomboid Minor
O: spines of C7-T1 I: medial (vertebral) border of scapula inferior to superior angle A: Elevates, medially rotates and adducts the scapula Innervation: dorsal scapular nerve
Rhomboid Major
O: spines of T2-T5 I: medial (vertebral) border of scapula A: Elevates, medially rotates and adducts the scapula Innervation: dorsal scapular nerve
Serratus Anterior
O: superior border of first 8 ribs I: Medial (vertebral) border of scapula A: abduction and lateral rotation of scapula - throwing the tennis ball up to serve Innervation: long thoracic nerve
pectoralis minor
O: superior margin of 3rd, 4th, and 5th rib I: Coracoid process of scapula A: Depress shoulder and assists in medially rotating scapula Innervation: medial anterior thoracic nerve
Supraspinatus
O: supraspinous fossa of scapula I: Greater tubercle of humerus A: abduction of humerus Innervation: suprascapular nerve 1 of the 4 rotator cuff muscles