Muscles Acting on the Arm

Muscles acting on the arm: pectoralis major, latissimus dorsi, deltoid, and teres major

pectoralis major origin: clavicle, sternum, cartilage of ribs

latissimus dorsi origin: spinous process of thoracic vertebrae, lumbar vertebrae, ribs, and iliac crest

deltoid origin: clavicle, acromion and spine of scapula

teres major origin: inferior angle of scapula

pectoralis major insertion: intertibercular sulus of humerus

latissimus dorsi insertion: intertibercular sulcus of humerus

deltoid insertion: deltoid tuberosity of humerus

teres major insertion: intertibercular sulcus of humerus

pectoralis major function: prime mover of arm flexion, rotates arm medially and adducts arm

latissimus dorsi function: prime mover of arm extension, adducts and medially rotates

deltoid function: prime mover of arm abduction

teres major function: synergist to latissimus dorsi (lats little helper)