Muscles of the Body Part C

1. Muscles of the Body Part C • Adapted for H. Biology II 2014-2015 • Muscles of Upper Extremities and Shoulder

2. Muscles Crossing the Shoulder Joint • Nine muscles cross the shoulder joint to insert on and move the humerus

3. Muscles Crossing the Shoulder Joint • Some originate off the scapula; others originate off the axial skeleton • Three are prime movers of the arm • Pectoralis major • Latissimus dorsi • Deltoid • Actions include flexion, extension, adduction, abduction, and rotation of humerus

4. Muscles Crossing the Shoulder Joint • Four muscles are rotator cuff muscles • Supraspinatus • Infraspinatus • Teres minor • Subscapularis • Reinforce the capsule of the shoulder • Act as synergists and fixators • Two additional muscles are synergists: coracobrachialis and teres major

5. Clavicle Deltoid Sternum Pectoralis major Coracobrachialis Triceps brachii: Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis (a) Anterior view Figure 10.14a

6. Supraspinatus* Spine of scapula Deltoid (cut) Greater tubercle of humerus Infraspinatus* Teres minor* Teres major Triceps brachii: Lateral head Long head Latissimus dorsi Humerus Olecranon process of ulna Anconeus (b) Posterior view * Rotator cuff muscles Figure 10.14b

7. Table 10.12 Part 1

8. Clavicle Deltoid Sternum Pectoralis major Coracobrachialis Triceps brachii: Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis (a) Anterior view Figure 10.14a

9. Muscles Crossing the Elbow Joint • Posterior extensor muscles • Triceps brachii—prime mover of forearm extension • Anconeus—weak synergist

10. Supraspinatus* Spine of scapula Deltoid (cut) Greater tubercle of humerus Infraspinatus* Teres minor* Teres major Triceps brachii: Lateral head Long head Latissimus dorsi Humerus Olecranon process of ulna Anconeus (b) Posterior view * Rotator cuff muscles Figure 10.14b

11. Lateral head Long head Triceps brachii Posterior compartment of arm (extends elbow); innervation: radial nerve Medial head Humerus Extensors Flexors Brachialis Others Short head Biceps brachii Long head (a) (a) Muscles of the arm Anterior compartment of arm (flexes elbow); innervation: musculocutaneous nerve Figure 10.17a

12. Table 10.12 Part 2

13. Muscles of the Forearm • Actions: movements of the wrist, hand, and fingers • Most anterior muscles are flexors and insert via the flexor retinaculum • Most posterior muscles are extensors and insert via the extensor retinaculum

14. Muscles of the Forearm • Some forearm muscles act to produce pronation and supination of the forearm

15. Muscles of the Forearm • Pronators: pronator teres and pronator quadratus • Supinator: a synergist with the biceps brachii

16. Muscles of the Forearm: Anterior Compartment • Flexors • Flexor carpi radialis • Palmaris longus • Flexor carpi ulnaris • Flexor digitorum muscles (superficialis and profundus) • Flexor pollicis longus

17. Superficial transverse ligament of palm Palmar aponeurosis Flexor retinaculum Pronator quadratus Flexor digitorum superficialis Flexor pollicis longus Flexor carpi ulnaris Extensor carpi radialis longus Palmaris longus Flexor carpi radialis Brachioradialis Pronator teres Medial epicondyle of humerus Tendon of biceps brachii Medial head of triceps brachii Biceps brachii (a) Figure 10.15a

18. Tendon of flexor digitorum superficialis (cut) Tendon of flexor digitorum profundus Lumbricals Tendon of flexor pollicis longus Thenar muscles of thumb Tendon of flexor carpi ulnaris (cut) Pronator quadratus Flexor pollicis longus Flexor digitorum profundus Supinator (c) Figure 10.15c

19. Muscles of the Forearm: Posterior Compartment • Extensors • Extensor carpi radialis longus and brevis • Extensor digitorum • Extensor carpi ulnaris • Extensor pollicis brevis and longus • Extensor indicis • Abductor pollicis longus

20. Extensor expansion Tendons of extensor digitorum Tendons of extensor carpi radialis brevis and longus Extensor pollicis longus Extensor indicis Extensor pollicis brevis Extensor digiti minimi Abductor pollicis longus Extensor carpi ulnaris Extensor digitorum Flexor carpi ulnaris Extensor carpi radialis brevis Anconeus Insertion of triceps brachii Extensor carpi radialis longus Brachioradialis (a) Figure 10.16a

21. Interossei Extensor indicis Extensor pollicis brevis Extensor pollicis longus Abductor pollicis longus Supinator Anconeus Olecranon process of ulna (b) Figure 10.16b

22. Posterior compartment of forearm (extends wrist and fingers); innervation: radial nerve Extensors Radius Ulna Abductor pollicis longus Others Pronator teres Flexors Brachioradialis (elbow flexor) (b) Muscles of the forearm (b) Extensors Flexors Anterior compartment of forearm (flexes wrist and fingers); innervation: median or ulnar nerve Others Figure 10.17b

23. Figure 10.12 Part 3

24. Intrinsic Muscles of the Hand • Small weak muscles • Lie entirely within the palm of the hand • Control precise movements of metacarpals and fingers (e.g., threading a needle) • Abductors and adductors of the fingers • Produce opposition—move the thumb toward the little finger

25. Finger and Thumb Movements • Flexion • Thumb—bends medially along the palm • Fingers—bend anteriorly • Extension • Thumb—points laterally • Fingers—move posteriorly

26. Intrinsic Muscles of the Hand • Three groups • Thenar eminence (ball of the thumb) • Hypothenar eminence (ball of the little finger) • Each of the above groups has a flexor, an abductor, and an opponens muscle • Midpalmar muscles: lumbricals and palmar and dorsal interossei extend the fingers • Interossei muscles also abduct and adduct the fingers

27. Tendons of: Flexor digitorum profundus Fibrous sheath Flexor digitorum superficialis Second lumbrical Dorsal interossei Third lumbrical First lumbrical Adductor pollicis Fourth lumbrical Flexor pollicis brevis Opponens digiti minimi Abductor pollicis brevis Flexor digiti minimi brevis Opponens pollicis Abductor digiti minimi Flexor retinaculum Pisiform bone Abductor pollicis longus Flexor carpi ulnaris tendon Tendons of: Palmaris longus Flexor digitorum superficialis tendons Flexor carpi radialis Flexor pollicis longus (a) First superficial layer Figure 10.18a

28. Flexor digitorum profundus tendon Flexor digitorum superficialis tendon Dorsal interossei Palmar interossei Adductor pollicis Opponens digiti minimi Flexor pollicis brevis Flexor digiti minimi brevis (cut) Abductor pollicis brevis Abductor digiti minimi (cut) Opponens pollicis Flexor pollicis longus tendon (b) Second layer Figure 10.18b

29. Palmar interossei (c) Palmar interossei (isolated) Figure 10.18c

30. Dorsal interossei (d) Dorsal interossei (isolated) Figure 10.18d