2nd Order Unit 2: upper limb & pectoral girdle

Pectoralis minor M

Origin: Ribs 3-5

Insertion: Coracoid process of scapula

Action: Protracts scapula; depresses scapula

Innervation: Medial pectoral nerve (C8-T1)

Deltoid M

Origin: Acromial end of clavicle; acromion and spine of scapula

Insertion: Deltoid tuberosity of humerus

Action: Anterior fibers: Flex arm; medially rotate arm

Middle fibers: Agonist of arm abduction

Posterior fibers: Extend arm; laterally rotate arm

Innervation: Axillary nerve (C5-C6)

Coracobrachialis M

Origin: Coracoid process of scapula

Insertion: Middle medial shaft of humerus

Action: Adducts arm; flexes arm

Innervation: Musculocutaneous nerve (C5-C6 fibers)

Brachialis M

Origin: Distal anterior surface of humerus

Insertion: Tuberosity and coronoid process of ulna

Action: Agonist of forearm flexion

Innervation: Musculocutaneous nerve (C5-C6 fibers)

Palmaris longus M

Origin: Medial epicondyle of humerus

Insertion: Flexor retinaculum and palmar aponeurosis

Action: Weak flexor of the hand at the wrist

Innervation: Median nerve (C6-C7 fibers)

Flexor carpi radialis M

Origin: Medial epicondyle of humerus

Insertion: Base of metacarpals II and III

Action: Flexes hand; abducts hand at the wrist

Innervation: Median nerve (C6-C7 fibers)

Flexor digitorum profundus M

Origin: Anteromedial surface of ulna; interosseous membrane

Insertion: Distal phalanges of fingers 2-5

Action: Flexes hand at the wrist; flexes MP joints; flexes PIP joints; flexes DIP joints of fingers 2-5

Innervation: Lateral one-half of muscle innervated by median nerve (C6-C8 fibers), medial one-half of muscle innervated by ulnar nerve (C8 fibers)

Pronator quadratus M

Origin: Distal one-fourth of ulna

Insertion: Distal one-fourth of radius

Action: Pronates forearm

Innervation: Median nerve (C8-T1 fibers)

Extensor digitorum M

Origin: Lateral epicondyle of humerus

Insertion: Distal and middle phalanges of fingers 2-5

Action: Extends hand at the wrist; extends MP joints; extends PIP joints; extends DIP joints of fingers 2-5

Innervation: Radial nerve (C6-C8 fibers)

Brachioradialis M

Origin: Lateral supracondylar ridge of humerus

Insertion: Styloid process of radius

Action: Flexes forearm

Innervation: Radial nerve (C6-C7 fibers)

Extensor pollicis brevis M

Origin: Posterior surface of radius; interosseous membrane

Insertion: Proximal phalanx of thumb

Action: Extends MP joints of thumb; extends hand at the wrist (weakly)

Innervation: Radial nerve (C6-C8 fibers)

Supinator M

Origin: Lateral epicondyle of humerus and ulna distal to radial notch

Insertion: Anterolateral surface of radius distal to radial tuberosity

Action: Supinates forearm

Innervation: Radial nerve (C6-C8 fibers)

Dorsal interossei M

Origin: Adjacent, opposing faces of metacarpals

Insertion: Dorsal tendons on fingers 2-5

Action: Abducts fingers 2-5; flexes MP joints of fingers 2-5; extends PIP joint; extends DIP joints of fingers 2-5

Innervation: Ulnar nerve (C8-T1)

Opponens pollicis M

Origin: Flexor retinaculum, trapezium

Insertion: Lateral side of metacarpal I

Action: Opposition of thumb

Innervation: Median nerve (C8-T1 fibers)

Flexor digiti minimi brevis M

Origin: Hamate bone, flexor retinaculum

Insertion: Proximal phalanx of finger 5

Action: Flexes little finger (finger 5)

Innervation: Ulnar nerve (C8-T1)

Triceps brachii M (long, lateral, and medial heads)

LONG

Origin: Infraglenoid tubercle of scapula

Insertion: Olecranon process of ulna

Action: Extends arm; adducts arm

Innervation: Radial nerve (C5-C7 fibers)

LATERAL

Origin: Posterior humerus proximal to radial groove

Insertion: Olecranon of ulna

Action: Primary extensor of forearm

Innervation: Radial nerve (C5-C7 fibers)

MEDIAL

Origin: Posterior humerus distal to radial groove

Insertion: Olecranon process of ulna

Action: Primary extensor of forearm

Innervation: Radial nerve (C5-C7 fibers)