O & I: Forearm Extensors Flashcards by Kate Ulrich

Origin: Brachioradialis

Proximal two thirds of supra-epicondylar ridge of humerus

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Insertion: Brachioradialis

lateral surface of distal end of radius proximal to styloid process

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Innervation: Brachioradialis

Radial Nerve (C5, C6, C7)

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Action: Brachioradialis

Relatively weak flexion of forearm; maximal when forearm is in neutral position

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Origin: Extensor Carpi Radialis Longus (ECRL)

Lateral supra-epicondylar ridge of humerus

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Insertion: Extensor Carpi Radialis Longus (ECRL)

Dorsal aspect of base of 2nd metacarpal

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Innervation: Extensor Carpi Radialis Longus (ECRL)

Radial Nerve (C6, C7)

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Action: Extensor Carpi Radialis Longus (ECRL)

Extend and abduct hand at the wrist joint; active during fist clenching

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Origin: Extensor Carpi Radialis Brevis (ECRB)

Lateral epicondyle of humerus

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Insertion: Extensor Carpi Radialis Brevis (ECRB)

Dorsal aspect of base of 3rd metacarpal

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Innervation: Extensor Carpi Radialis Brevis (ECRB)

Deep Branch of radial nerve (C7, C8)

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Action: Extensor Carpi Radialis Brevis (ECRB)

Extend and abduct hand at the wrist joint

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Origin: Extensor Digitorum

Lateral epicondyle of humerus

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Insertion: Extensor Digitorum

Extensor expansions of medial 4 digits

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Innervation: Extensor Digitorum

Deep Branch of radial nerve (C7, C8)

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Action: Extensor Digitorum

Extends medial four digits primarily at metacarpophalangeal joints, secondarily at interphalangeal joints

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Origin: Extensor Digiti Minimi (EDM)

Lateral epicondyle of humerus

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Insertion: Extensor Digiti Minimi (EDM)

Extensor expansion of 5th digit

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Innervation: Extensor Digiti Minimi (EDM)

Deep Branch of radial nerve (C7, C8)

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Action: Extensor Digiti Minimi (EDM)

Extends 5th digit primarily at metacarpophalangeal joint, secondarily at interphalangeal joint

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Origin: Extensor Carpi Ulnaris (ECU)

Lateral epicondyle of humerus; posterior border of ulna via a shared aponeurosis

Insertion: Extensor Carpi Ulnaris (ECU)

Dorsal aspect of base of 5th metacarpal

Innervation: Extensor Carpi Ulnaris (ECU)

Deep Branch of radial nerve (C7, C8)

Action: Extensor Carpi Ulnaris (ECU)

extends and adducts hand at wrist joint (also active during fist clenching)

Origin: Supinator

lateral epicondyle of humerus; radial collateral and anular ligaments; supinator fossa; crest of ulna

Insertion: Supinator

lateral, posterior, and anterior surfaces of proximal third of radius

Innervation: Supinator

Deep Branch of radial nerve (C7, C8)

Action: Supinator

supinates forearm; rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)

Origin: Extensor Indicis

Posterior surface of distal third of ulna and interosseous membrane

Insertion: Extensor Indicis

Extensor expansion of 2nd digit

Innervation: Extensor Indicis

Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve

Action: Extensor Indicis

extends 2nd digit (enabling its independent extension); helps extend hand at wrist

Origin: Abductor Pollicis Longus (APL)

posterior surface of proximal halves of ulna, radius, and interosseous membrane

Insertion: Abductor Pollicis Longus (APL)

base of 1st metacarpal

Innervation: Abductor Pollicis Longus (APL)

posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve

Action: Abductor Pollicis Longus (APL)

abducts thumb and extends it at carpometacarpal joint

Origin: Extensor Pollicis Longus (EPL)

posterior surfae of middle third of ulna and interosseous membrane

Insertion: Extensor Pollicis Longus (EPL)

dorsal aspect of base of distal phalanx of thumb

Innervation: Extensor Pollicis Longus (EPL)

posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve

Action: Extensor Pollicis Longus (EPL)

extends distal phalanx of thumb at interphalangeal joint; extends metacarpophalangeal and carpometacarpal joints

Origin: Extensor Pollicis Brevis (EPB)

posterior surface of distal third of radius and interosseous membrane

Insertion: Extensor Pollicis Brevis (EPB)

dorsal aspect of base of proximal phalanx of thumb

Innervation: Extensor Pollicis Brevis (EPB)

posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve

Action: Extensor Pollicis Brevis (EPB)

extends proximal phalanx of thumb at metacarpophalangeal joint; extends carpometacarpal joint

Origin: Triceps Brachii

Long Head: infraglenoid tubercle of scapula Lateral Head: posterior surface of humerus, superior to radial groove Medial Head: posterior surface of humerus, inferior to radial groove

Insertion: Triceps Brachii

Proximal end of olecranon of ulna and fascia of forearm

Innervation: Triceps Brachii

radial nerve (C6, C7, C8)

Action: Triceps Brachii

Chief extensor of forearm; long head resists dislocation of humerus; especially important during adduction

Origin: Anconeus

lateral epicondyle of humerus

Insertion: Anconeus

lateral surface of olecranon and superior part of posterior surface of ulna

Innervation: Anconeus

Radial nerve (C7, C8, T1)

Action: Anconeus

assists triceps in extending forearm; stabilizes elbow joint; may abduct ulna during pronation