ORIGIN INSERTION ACTION AGONIST NAME Head and Neck Buccinator pterygomandibu lar raphe mandible and the maxilla lateral to the molar teeth angle of mouth and the lateral portion of the upper and lower lips pulls the corner of mouth laterally presses the cheek against the teeth Synergist Risorius frontalis galea aponeurotica skin of the eyebrow elevates the eyebrows and wrinkles the forehead elevates the mandible masseter zygomatic arch and zygomatic bone medial orbital margin and the lateral surface of the ramus and angle of the mandible orbital part skin of the lateral cheek palpebral orbicularis oculi orbital part closes the eyelids No synergist or antagonist for orbicularis oris skin and fascia of the lips purses the lips No synergist or antagonist for part lateral palpebral raphe medial palpebral ligament palpebral part medial palpebral ligament skin and fascia of lips and the area surrounding the lips sternal head anterior surface of the manubrium clavicular head medial 1 3rd of the clavicle sternocleidomas toid mastoid process and lateral 1 2 of the superior nuchal line temporalis temporal fossa and the temporal fascia coronoid process of the mandible and the anterior surface of the ramus of the mandible Trunks and Brachial Region biceps brachii short head tip of the coracoid process of the scapula long head supraglenoid tubercle of the scapula brachialis anterior surface coronoid flexes the tuberosity of the radius flexes the forearm flexes arm long head supinates Elbow Flexion draws the mastoid process down toward the same side which causes the chin to turn up toward the opposite side acting together the muscles of the two sides flex the neck elevates the mandible retracts the mandible posterior fibers deltoid of the lower one half of the humerus and the associated intermuscular septa lateral one third of the clavicle acromion the lower lip of the crest of the spine of the scapula process of the ulna forearm deltoid tuberosity of the humerus abducts arm anterior fibers flex medially rotate the arm posterior fibers extend laterally rotate the arm Shoulder Flexion Shoulder Extension Shoulder Abduction Intercostals externals lower border of a rib within an intercostal space Intercoastals internal upper border of a rib upper border of the rib below coursing downward and medially lower border of rib above coursing up and medially keeps the intercostal space from blowing out or sucking in during respiration keeps the intercostal space from blowing out or sucking in during respiration latissimus dorsi vertebral spines floor of the intertubercular groove extends the arm and rotates the arm medially Shoulder Adduction from T7 to the sacrum posterior third of the iliac crest lower 3 or 4 ribs sometimes from the inferior angle of the scapula processes of C1 C4 vertebrae levator scapulae transverse medial border of the scapula from the superior angle to the elevates the scapula rectus abdominis pubis and the pubic symphysis Spine Flexion pectoralis major medial 1 2 of spine crest of the greater tubercle of the humerus flexes and adducts the arm medially rotates the arm shoulder adduction the clavicle manubrium body of sternum costal cartilages of ribs 2 6 sometimes from the rectus sheath of the upper abdominal wall pectoralis minor ribs 3 5 serratus anterior ribs 1 8 or 9 subscapularis medial two thirds of the costal surface of the scapula subscapular fossa supraspinatus supraspinatous fossa coracoid process of the scapula xiphoid process of the sternum and costal cartilages 5 7 medial border of the scapula on its costal deep surface lesser tubercle of the humerus draws the scapula forward medialward and downward flexes the trunk it draws the scapula forward the inferior fibers rotate the scapula superiorly medially rotates the arm assists extention of the arm greater tubercle of the humerus highest facet abducts the arm initiates abduction Shoulder Medial Rotation teres major dorsal surface of the inferior angle of the scapula crest of the lesser tubercle of the humerus adducts the arm medially rotates the arm assists in arm extension Shoulder Medial Rotation teres minor Transversus abdominis trapezius upper 2 3 of the lateral border of the scapula greater tubercle of the humerus lowest facet laterally rotates the arm Shoulder Lateral Rotation linea alba pubic crest and pecten of the pubis flexes and laterally bends trunk lateral third of the clavicle medial side of the acromion and the upper crest of the scapular spine tubercle of the scapular spine olecranon process of the ulna elevates and depresses the scapula depending on which part of the muscle contracts rotates the scapula superiorly retracts scapula extends the forearm the long head extends and adducts arm lower 6 ribs thoracolumbar fascia anterior 3 4 of the iliac crest lateral 1 3 of inguinal ligament medial third of the superior nuchal line external occipital protuberance ligamentum nuchae spinous processes of vertebrae C7 T12 long head infraglenoid tubercle of the scapula lateral head posterolateral humerus lateral intermuscular septum medial head posteromedial surface of the inferior 1 2 of the humerus triceps brachii Elbow Extension Pelvic and Femoral Regions adductor longus medial portion of the superior linea aspera of the femur adducts flexes and medially Hip Adduction rotates the femur adducts flexes and medially rotates the femur extends the femur ischiocondylar part extends the thigh flexes the leg Hip Adduction Knee Flexion extends the thigh laterally rotates the femur Hip Extension Hip Lateral Rotation linea aspera of the femur the ischiocondylar part inserts on the adductor tubercle of the femur head of fibula and lateral condyle of the tibia upper fibers iliotibial tract lowermost fibers gluteal tuberosity of the femur adductor magnus biceps femoris gluteus maximus pubic ramus ischiopubic ramus and ischial tuberosity long head ischial tuberosity short head lateral lip of the linea aspera posterior gluteal line posterior surface of sacrum and coccyx sacrotuberous ligament of the ilium between the posterior and anterior gluteal lines gluteus medius external surface greater trochanter of the femur abducts the femur medially rotates the thigh gracilis iliacus pubic symphysis and the inferior pubic ramus medial surface of the tibia via pes anserinus iliac fossa and iliac crest ala of sacrum lesser trochanter of the femur adducts the thigh flexes and medially rotates the thigh flexes the leg flexes the thigh if