Chapter 6 The Muscular System 189 Copyright Goodheart-Willcox Co., Inc. Scapula Clavicle Humerus Latissimus dorsi Lateral head Deltoid Sternum Pectoralis major Biceps brachii Brachialis Brachioradialis Anterior view Posterior view Triceps brachii Long head © Body Scientific International Figure 6.19 Muscles of the upper limb. The medial head of the triceps shares the proximal tendon of the lateral head, so the muscle is concealed behind the lateral and long heads in this illustration. Muscles of the Upper Limb Shoulder Muscles Muscle Origin Insertion Primary Functions Pectoralis major sternum, clavicle, and ribs 1–7 proximal humerus adduction and flexion of arm Deltoid scapular spine, acromion, and clavicle deltoid tuberosity of humerus prime mover for abduction assists with flexion, extension, and rotation of arm Latissimus dorsi lower 6 thoracic and all lumbar vertebrae, ribs 10–12, sacrum, and iliac crest anterior humerus extension, adduction, and medial rotation of arm Elbow Muscles Muscle Origin Insertion Primary Functions Biceps brachii superior glenoid fossa and coracoid process radial tuberosity assists with flexion and supination of forearm Brachialis humerus ulna flexion of forearm Brachioradialis distal styloid process of the radius lateral supracondylar ridge of the humerus flexion of forearm Triceps brachii inferior glenoid fossa and entire humeral shaft olecranon process of ulna extension of forearm Figure 6.20 Goodheart-Willcox Publisher