Muscles of Upper Appendage (Shoulder, Arm, Forearm, & Hand) Nestor T. Hilvano M.D., M.P.H.

Learning Objectives You should be able to: Identify the principal muscles of the shoulder and upper limbs and indicate their origin, insertions, actions, and innervation. Explain common anatomic and physiologic problems based on what you have learned on this topic.

Muscles on Pectoral Girdle Originate on axial skeleton and insert onto clavicle or scapula: Trapezius, Rhomboid major and minor, Levator scapulae, Serratus anterior, Subclavius, Pectoralis muscle Scapular movements produced include medial and lateral rotation elevation and depression protraction and retraction ___ What bone braces the shoulder and limits movement? a. clavicle b. first rib c. sternum d. humerus

Muscles on Pectoral Girdle Anterior Scapular Muscles Pectoralis Minor - ribs 3-5 to coracoid process of scapula - protracts and depresses shoulder Serratus Anterior - ribs 1-9 to medial border of scapula - protracts and rotates shoulder - throwing muscle Subclavius - rib 1 to clavicle - depresses and protracts clavicle

Muscles on Pectoral Girdle Posterior Scapular Muscles Trapezius - occipital bone, spinous processes of thoracic vertebrae to clavicle and scapula - action: rotate upward, retract, & depress scapula Levator scapulae - C1-C4 to superior angle of scapula - action: elevate shoulder Rhomboid m. = C7- T1 to medial border of scapula - action: adduct scapula & downward rotation ___ What muscles are used in shrugging your shoulders? a. trapezius b. rhnomboid c. levator scapulae d. teres minor

Muscles that Move the Arm ___ What is the major abductor of the arm? a. deltoid b. teres major c. teres minor d. coracobrachialis Deltoid – scapula to deltoid tuberosity of humerus; prime mover; flexion, extension, abduction of humerus Coracobrachialis- assists in flexion & adduction at shoulder joint Teres major- assists in extension & medial rotation at shoulder joint

Muscles that Move the Arm Pectoralis major - from anterior chest to crest of greater tubercle of humerus - flexion at shoulder Latissimus dorsi - from thoracic vertebrae to intertubercular groove of humerus - extension at shoulder

Rotator Cuff Muscles (SITS) Extending from posterior scapula to humerus - Supraspinatus (abducts) Infraspinatus and Teres minor (lateral rotation at shoulder) Extending from anterior scapula to humerus - subscapularis (medial rotation) What muscles are used in throwing a baseball?

Muscles that move the Forearm Principal flexors biceps brachii Origin on scapula, inserts on radius brachialis inserts on ulna Synergistic flexor brachioradialis Prime extensor triceps brachii Origin on scapula, inserts onto olecranon of ulna

Muscles of Anterior Forearm Action: Flex wrist and fingers, adduct, &/or abduct wrist Flexor carpi radialis, palmaris longus, & flexor carpi ulnaris FCR, PL (median n.); FCU (ulnar n) Flexor digitorum superficialis Flexor pollicis longus, flexor digitorum profundus

Muscles of Posterior Forearm Action: Extension of wrist and fingers, adduct &/or abduct wrist Innervation - radial nerve Extensor carpi radialis, extensor digitorum, extensor carpi ulnaris, anconeus (extend at elbow), supinator, abductor pollicis longus, extensor pollicis longus, extensor indicis Tennis elbow- inflammation at origin of ___ (a. flexor; b. extensor) carpi muscles.

Muscles of Hand and Fingers Extrinsic muscles – strength and crude control Intrinsic muscles – fine control - Thenar group = fleshy base of thumb muscles (abductor pollicis brevis,opponens pollicis, adductor pollicis - Hypothenar group = base of little finger muscles (abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi) - Midpalmar group = Interosseus m. and Lumbrical m. Flexor retinaculum – tendon passes underneath except palmaris longus.

Carpal Tunnel Syndrome Repetitive motions cause inflammation and pressure on _____ nerve which innervates the hand. Impairment of pronation of forearm and weakens flexion of wrist (chronic pain) a. Median nerve b. radial nerve c. ulnar nerve d. axillary nerve

Muscles that move the Forearm and Hand Biceps brachii, brachialis, brachioradialis – flexes the _________________________ Triceps brachii – extends the __________ Flexor carpi ulnaris, flexor carpi radialis, and palmaris longus – flexion of ____________ Extensor carpi radialis and extensor carpi ulnaris – extension and abduction, and extension and adduction of _______________ Pronator teres and pronator quadratus - pronate _______________________

Homework (Self Review) Describe carpal tunnel syndrome. What is flexor retinaculum and it’s importance? Name the muscles involved in the following: ___ extends the shoulders a. subclavius ___ throwing a ball b. extnesor carpi radialis ___ shrugging the shoulders c. flexor carpi radialis ___ flexes the shoulders d.supraspinatus ___ extend the forearm/elbow e. biceps ___ major abductor of arm f. triceps ___ flexion of wrist g. deltoid ___ flexion of elbow/move forearm up h. pectoralis major ___ extension of wrist i. levator scapulae ___ depresses the clavicle j. latissimus dorsi