Extensor Muscles of Arm

Question 1

Brachialradialis

Answer 1

Origin: Lateral suracondylar ridge

Lateral intermuscular septum

Insertion: Lateral side distal end radius

Actions: Flex forearm at elbow

Innervation: Radial nerve (C5, C6)

Question 2

Extensor carpi radialis longus

Answer 2

Origin: Lateral supracondylar ridge

Lateral intermuscular septum

Lateral epicondyle (CET)

Insertion: Base 2nd metacarpal

Actions: Extension/radial deviation

Innervation: Radial nerve (C6, C7)

Question 3

Extensor carpi radialis brevis

Answer 3

Origin: Lateral epicondyle (CET)

Intermusclular septum

Antebrachial fascia

Insertion: Base 3rd metacarpal

Actions: Extension

Innervation: Radial nerve (C6, C7)

Question 4

Extensor digitorum

Answer 4

Origin: Lateral epicondyle (CET)

Intermuscular septum

Antebrachial fascia

Insertion: Middle/distal phalanges 4 medial digits

Actions: Extension 4 fingers

Innervation: Radial nerve (C6-C8)

Question 5

Extensor digiti minimi

Answer 5

Origin: Lateral epicondyle (CET)

Intermuscular septum (extensor digitorum)

Insertion: Middle/distal phalanx little finger

Actions: Extension/abduction little finger

Innervation: Radial nerve (C6-C8)

Question 6

Extensor carpi ulnaris

Answer 6

Origin: Lateral epicondyle (CET)

Proximal 1/2 posterior border ulna

Insertion: Base 5th metacarpal

Actions: Extension/ulnar deviation

Innervation: Radial nerve (C7, C8)

Question 7

Supinator

Answer 7

Origin: Lateral epicondyle

Post/lat surface ulna below radial notch

Radial collateral/annular ligaments

Insertion: Lateral ant/post aspects proximal shaft of radius

Actions: Supination forearm

Innervation: Radial nerve (C5, C6)

Question 8

Abductor pollicis longus

Answer 8

Origin: Post. surface ulna/radius

Interosseus membrane

Insertion: Base 1st metacarpal

Actions: Abduction/External thumb

Abduction/Flexion hand

Innervation: Radial nerve (C6-C8)

Question 9

Extensor pollicis brevis

Answer 9

Origin: Post. surface radius

Interosseuous membrane

Insertion: Proximal phalanx thumb

Actions: Extend proximal phalanx/metacarpal thumb

Abduction on hand at wrist

Innervation: Radial nerve (C7,C8)

Question 10

Extensor pollicis longus

Answer 10

Origin: Post. surface middle 1/3 ulna

Interosseuous membrane

Insertion: Distal phalanx thumb

Actions: Extend proximal/distal phalanges thumb

Extend/adduct in metacarpal thumb

Innervation: Radial nerve (C7, C8)

Question 11

Extensor indicis

Answer 11

Origin: Posterior surface ulna

Interosseuous membrane

Insertion: Extensor expansion of index finger

Actions: Extensor adduction index finger

Innervation: Radial nerve (C7, C8)