Muscle Name Muscle Action Synergist(s) Antagonist(s) Masseter Elevates mandible temporalis digastric Temporalis elevates mandible masseter digastric Digastric depresses mandible N/A masseter temporalis Sternohyoid depresses hyoid Thyrohyoid N/A Sternothyroid depresses thyroid cartilage (larynx) N/A Thyrohyoid Thyroid elevates larynx or depresses hyoid bone Sternohyoid Sternothyroid Sternocleidomastoid flexes or rotates the head N/A N/A Clavotrapezius flexes neck laterally or elevates clavicle N/A N/A Acromiotrapezius adducts scapula Rhomboideus N/A Spinotrapezius depresses scapula Pectoralis Minor Rhomboideus Levator scapulae Pectoralis Minor steadies & depresses scapula Spino-trapezius Rhomboideus Levator scapulae Levator Scapulae elevates scapula Rhomboideus Spino-trapezius Pectoralis Minor Serratus Anterior Anterior rotation of scapula N/A N/A Rhomboideus adducts & elevates scapula Acromio-trapezius Spino-trapezius Levator scapulae Pectoralis Minor Clavo-deltoid Acromio-deltoid Pectoralis Major flexes & adducts humerus Latissimus dorsi Spino-deltoid Supraspinatus Clavodeltoid flexes & adducts humerus Pectoralis major Pectoralis Major Latissimus dorsi Supraspinatus Acromiodeltoid Spinodeltoid abducts humerus extends humerus Supraspinatus Clavo-deltoid Latissimus dorsi Pectoralis Major N/A Pectoralis Major Clavo-deltoid Infraspinatus lateral rotation of the humerus N/A Teres Major Subscapularis Supraspinatus abducts humerus Acromio-deltoid Pectoralis Major Latissimus dorsi Clavo-deltoid Subscapularis medial rotation of the humerus Teres Major Infraspinatus Latissimus Dorsi adducts humerus Acromio-deltoid Pectoralis major Supraspinatus Clavo-deltoid Teres Major medial rotation of humerus Subscapularis Infraspinatus Triceps Brachii extends forearm N/A Biceps brachii Brachialis Brachioradialis Biceps Brachii flexes forearm Brachialis Brachioradialis Triceps brachii Brachialis flexes forearm Biceps brachii Triceps brachii Brachioradialis Brachioradialis flexes forearm Biceps brachii Triceps brachii Brachialis Pronator Teres pronation N/A Supinator Supinator supination N/A Pronator teres Extensor Carpi Radialis Brevis extends wrist Extensor carpi radialis brevis Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Extensor Carpi Radialis Longus extends wrist Extensor carpi radialis ulnaris Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Extensor Digitorum Extends digit 2-5 Extensor digiti minimi Flexor digitorum superficialis Flexor digitorum profundus Extensor Digiti Minimi Extends digit 5 Extensor digitorum Flexor digitorum superficialis Flexor digitorum profundus Extensor Carpi Ulnaris Extends wrist Extensor carpi radialis brevis Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor Carpi Radialis Flexes wrist Palmaris longus Extensor carpi radialis brevis Flexor carpi radialis Extensor carpi radialis ulnaris Palmaris Longus flexes wrist Flexor carpi radialis Extensor carpi radialis brevis Flexor carpi ulnaris Extensor carpi radialis ulnaris Flexor Carpi Ulnaris flexes wrist Flexor carpi radialis Extensor carpi radialis brevis Palmaris longus Extensor carpi radialis ulnaris Flexor Digitorum Superficialis flexes middle phalanges 2-5 Flexor digitorum profundus Extensor digitorum Extensor digiti minimi Flexor Digitorum Profundus flexes distal phalanges 2-5 Flexor digitorum superficialis Extensor digitorum Extensor digiti minimi Abductor Pollicis Brevis abducts thumb N/A N/A