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Muscles Crossing Shoulder & Elbow Joints: Anatomy & Function

This educational video explores the muscles that cross the shoulder and elbow joints, including their origins, actions, and roles as prime movers, synergists, and fixators. It also discusses the anatomy and function of the rotator cuff muscles and the flexor and extensor muscles of the forearm.

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Muscles Crossing Shoulder & Elbow Joints: Anatomy & Function

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  1. 10 The Muscular System: Part C

  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 PLAY A&P Flix™: Pectoralis major PLAY A&P Flix™: Latissimus dorsi PLAY A&P Flix™: Deltoid

  5. 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

  6. Muscles Crossing the Shoulder Joint PLAY A&P Flix™: Muscles that cross the glenohumeral joint PLAY A&P Flix™: Movement from the rotator cuff muscles (a) PLAY A&P Flix™: Movement from the rotator cuff muscles (b) PLAY A&P Flix™: Teres Major

  7. Rotator Cuff Anatomy and Function PLAY A&P Flix™: Subscapularis PLAY A&P Flix™: Supraspinatus PLAY A&P Flix™: Infraspinatus PLAY A&P Flix™: Teres minor PLAY A&P Flix™: Rotator cuff muscles

  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. Rotator Cuff Anatomy and Function PLAY A&P Flix™: Scapular muscles of the glenohumeral joint (a) PLAY A&P Flix™: Axial muscles of the glenohumeral joint (a)

  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. Rotator Cuff Anatomy and Function PLAY A&P Flix™: Scapular muscles of the glenohumeral joint (b) PLAY A&P Flix™: Axial muscles of the glenohumeral joint (b)

  12. Table 10.12 Part 1

  13. Movement at the Glenohumeral Joint PLAY A&P Flix™: Movement at the glenohumeral joint: An overview PLAY A&P Flix™: Movement at the glenohumeral joint (a) PLAY A&P Flix™: Movement at the glenohumeral joint (b)

  14. Muscles Crossing the Elbow Joint • Anterior flexor muscles • Brachialis and biceps brachii—chief forearm flexors • Brachioradialis—synergist and stabilizer PLAY A&P Flix™: The elbow joint and forearm: An overview PLAY A&P Flix™: Muscles of the elbow joint (a)

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

  16. Muscles Crossing the Elbow Joint PLAY A&P Flix™: Muscles of the elbow joint (b) PLAY A&P Flix™: Biceps brachii PLAY A&P Flix™: Brachialis PLAY A&P Flix™: Brachioradialis

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

  18. 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

  19. Muscles Crossing the Elbow Joint PLAY A&P Flix™: Muscles of the elbow joint (c) PLAY A&P Flix™: Triceps brachii

  20. 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 PLAY A&P Flix™: Movement at the elbow joint Figure 10.17a

  21. Table 10.12 Part 2

  22. 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 PLAY A&P Flix™: Muscles that act on the wrist and fingers: An overview

  23. Muscles of the Forearm • Some forearm muscles act to produce pronation and supination of the forearm PLAY A&P Flix™: Muscles of the forearm (a)

  24. Muscles of the Forearm • Pronators: pronator teres and pronator quadratus • Supinator: a synergist with the biceps brachii PLAY A&P Flix™: Muscles of the forearm (b) PLAY A&P Flix™: Muscles of the forearm (c) PLAY A&P Flix™: Pronator teres PLAY A&P Flix™: Supinator

  25. Muscles of the Forearm: Anterior Compartment • Flexors • Flexor carpi radialis • Palmaris longus • Flexor carpi ulnaris • Flexor digitorum muscles (superficialis and profundus) • Flexor pollicis longus PLAY A&P Flix™: Carpal tunnel

  26. 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

  27. Muscles of the Forearm: Anterior Compartment PLAY A&P Flix™: Anterior Muscles of the wrist and fingers (b) PLAY A&P Flix™: Flexor carpi radialis PLAY A&P Flix™: Flexor carpi ulnaris PLAY A&P Flix™: Flexor digitorum superficialis

  28. 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

  29. Muscles of the Forearm: Anterior Compartment PLAY A&P Flix™: Anterior Muscles of the wrist and fingers (a)

  30. 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

  31. 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

  32. Muscles of the Forearm: Posterior Compartment PLAY A&P Flix™: Posterior Muscles of the wrist and fingers (b) PLAY A&P Flix™: Extensor carpi radialis longus PLAY A&P Flix™: Extensor carpi radialis brevis PLAY A&P Flix™: Extensor digitorum PLAY A&P Flix™: Extensor carpi ulnaris(c)

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

  34. Muscles of the Forearm: Posterior Compartment PLAY A&P Flix™: Posterior Muscles of the wrist and fingers (a)

  35. Movements of the Wrist and Fingers • Flexion and extension • Abduction and adduction PLAY A&P Flix™: Movements of the wrist and fingers (a) PLAY A&P Flix™: Movements of the wrist and fingers (b)

  36. 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

  37. Figure 10.12 Part 3

  38. 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

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

  40. 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

  41. 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

  42. 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

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

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

  45. Intrinsic Muscles of the Hand PLAY Animation: Rotating hand

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