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Muscles of the Scapula Stabilize the Scapula – All Insert on the scapula Muscle/Nerve Origin Trapezius – Spinal accessory nerve (XI) Ligamentum nuchae and C7 - T12 Levator Scapulae (Ventralis) – Dorsal scapular nerve and the anterior rami of C3 and C4 (lateral branches of cervical spinal nerves 3-5) Rhomboids – Dorsal scapular nerve Pectoralis Minor – Medial pectoral nerve (lateral branches of cervical spinal nerves C7, C8, and T1) Serratus Anterior (Ventralis) – Long thoracic nerve Action Elevates, retracts (ADducts), rotates, and depresses the scapula. C1 - C4 Elevates the scapula, flexes neck laterally (lateral side bending), and rotates the scapula. C7 - T5 Retracts (ADducts), elevates, and rotates the scapula Ribs 3 - 5 Depresses, protracts (ABducts), and rotates the scapula. Ribs 1 - 9 Protracts (ABducts) and rotates the scapula. Muscles of the Upper Limb “Rotator Cuff” (SITS) – All Insert on the humerus and originate on the scapula Muscle/Nerve Supraspinatus – Suprascapular nerve Infraspinatus – Suprascapular nerve Teres Minor – Axillary nerve Subscapularis – Upper and Lower subscapular nerves (C5 and C6) Origin Supraspinous fossa of scapula Infraspinous fossa of scapula Lateral (axillary) border of scapula (superior 2/3 ) Subscapular fossa of scapula Action ABducts the arm (humerus) Laterally rotates the arm (humerus) Medially rotates the arm (humerus) Muscles of the Upper Limb Move the arm – All Insert on the humerus Muscle/Nerve Origin Deltoid – Axillary nerve Lateral 1/3 of the clavicle, acromion, and spine of the scapula Pectoralis Major – Medial and Lateral Pectoral nerves (C5 - T1) Latissimus Dorsi – Thoracodorsal nerve Teres Major – Lower Subscapular nerve Coracobrachialis – Musculocutaneous nerve Sternum, costal cartilage of ribs 1-6 (or 7), clavicle, and aponeurosis of the external oblique muscle Iliac crest, T7 – T12 , ribs 10-12, and the lumbar fascia Lateral (axillary) border of scapula (inferior 1/3) Coracoid process of the scapula Action Prime flexor and ABdctor of the arm (humerus). Extends and hyperextends the arm (humerus); laterally and medially rotates the arm (humerus). ADducts, flexes, and medially rotates the arm (humerus), sternal portion extends the arm (humerus). Extends, hyperextends, ADducts, and medially rotates the arm (humerus). Extends, ADducts, and medially rotates the arm (humerus). Flexes and ADducts the arm (humerus); stabilizes the shoulder joint. Muscles of the Forearm Move the Forearm Muscle/Nerve Origin and Insertion Action FLEXORS Brachialis – Musculocutaneous nerve Origin: Supraglenoid tubercle and coracoid process of the scapula Insertion: radial tuberosity of radius and bicipital aponeurosis Origin: Anterior surface of the humerus Insertion: ulna Brachioradialis – Radial nerve Origin: Supracondylar ridge of the humerus Insertion: radius Biceps Brachii – Musculocutaneous nerve Flexes the forearm and supinates (laterally rotates) forearm and wrist (hand); short head flexes the arm (humerus). Flexes the forearm. Flexes the forearm (stabilizes forearm for small, quick, movements – “hammering muscle”). EXTENSORS Triceps Brachii – Radial nerve Anconeus – Radial nerve Origin: Infraglenoid tubercle and shaft of the humerus Insertion: ulna Origin: Lateral epicondyle of the humerus Insertion: ulna Extends the forearm; long head extends and adducts arm (humerus). Extends the forearm. Muscles of the Hand Move the hand Muscle/Nerve PRONATORS: Pronator Teres – Median nerve Pronator Quadratus – Median nerve SUPINATORS: Supinator – Radial nerve Biceps Brachii – Musculocutaneous nerve Origin and Insertion Origin: medial epicondyle of the humerus and coronoid process of the ulna. Insertion: lateral aspect of the radius at its midpoint Origin: distal ¼ of the ulna. Insertion: distal ¼ of the radius. Origin: lateral epicondyle of the humerus and posterio-lateral proximal ulna. Insertion: anterior proximal radius. Origin: supraglenoid tubercle and coracoid process of the scapula. Insertion: radial tuberosity of the radius and bicipital aponeurosis. Action Pronates (medially rotates) forearm and wrist (hand); assists elbow flexion. Pronates (medially rotates) forearm and wrist (hand). Supinates (laterally rotates) forearm and wrist (hand). Flexes the forearm and supinates (laterally rotates) forearm and wrist (hand); short head flexes the arm (humerus). Muscles of the Wrist or the Digits Move the wrist or the digits – All Insert on the carpals or digits Muscle/Nerve FLEXORS Flexor Carpi Radialis – Median nerve Flexor Digitorum Superficialis – Median nerve Palmaris Longus (human only) – Median nerve Flexor Carpi Ulnaris – Ulnar nerve Flexor Digitorum Profundus – ½ Median nerve and ½ Ulnar nerve EXTENSORS Extensor Carpi Radialis Longus – Radial nerve Extensor Carpi Radialis Brevis – Radial nerve Extensor Digitorum (Communis) – Radial nerve Extensor Digitorum Lateralis (cat only) – Radial nerve Extensor Carpi Ulnaris – Radial nerve Origin Medial epicondyle of the humerus at the common flexor tendon (*Note: Flexor digitorum superficialis has a broad origin that includes parts of the radius and ulna.) Proximal 75% of the ulna Lateral supracondylar ridge of the humerus Lateral epicondyle of the humerus at the common extensor tendon Lateral epicondyle of the humerus Lateral epicondyle of the humerus at the common extensor tendon Action Flexes and ABducts the wrist (hand) Flexes the wrist (hand) and the digits 2-5. Flexes the wrist (hand). Flexes and ADducts the wrist (hand). Flexes the wrist (hand) and the digits 2-5. Extends and ABducts the wrist (hand). Extends the wrist (hand) and the digits 2-5. Extends the digits. Extends and ADducts the wrist (hand). Sources: Louis J.Zanella, The Human Body - An Owners Manual – 1995 Modified by William C. Johnson (Dr. J) – 2008, to be simplified and yet consistent with Drake et al. -2010. (Most recent update – 8/11/13)