Posterior forearm

Question 1

Brachioradialis

Answer 1

Origin-Supracondylar ridge of humerus

Insertion-Distal lateral radius

Innervation-Radial n.

Action-Flexes forearm at elbow, strongly when in mid-prone position

Question 2

Extensor carpi radialis longus

Answer 2

Origin-Supracondylar ridge of humerus

Insertion-Base of 2nd metacarpal

Innervation-Radial n.

Action-Extend and abduct the hand at the wrist, also active during fist clenching

Question 3

Extensor carpi radialis brevis

Answer 3

Origin-Lateral epicondyle via common extensor tendon

Insertion-Base of 3rd metacarpal

Innervation-Radial n.

Action-Extend and abduct the hand at the wrist

Question 4

Extensor digitorum

Answer 4

Origin-Lateral epicondyle via common extensor tendon

Insertion-Extensor expansion of digits 2-5

Innervation-Radial n.

Action-1) primary extension at MCP joint digits 2-5 2) Secondary extension at IP joints (distal, middle, and proximal phalanges)

Question 5

Extensor digiti minimi

Answer 5

Origin-Lateral epicondyle via common extensor tendon

Insertion-Extensor expansion of digit 5

Innervation-Radial n.

Action-1) Primary extension at MCP joint digit 5 2) Secondary extension at interphalangeal joints of digit 5

Question 6

Extensor carpi ulnaris

Answer 6

Origin-2 heads: Lateral epicondyle and posterior border of ulna

Insertion-Base of 5th metacarpal

Innervation-Radial n.

Action-Extends and adducts the hand at the wrist

Question 7

Supinator

Answer 7

Origin-Lateral epicondyle, radial collateral and annular ligament, ulna

Insertion-Proximal 1/3 of radius

Innervation-Radial n.

Action-Supinates forearm

Question 8

Abductor pollicis longus

Answer 8

Origin-Proximal 1/2 of ulna, radius and interosseous membrane

Insertion-Base of 1st metacarpal

Innervation-Radial n.

Action-Abducts thumb and extends it at the carpometacarpal joint

Question 9

Extensor pollicis brevis

Answer 9

Origin-Distal 1/3 of posterior radius and interosseous membrane

Insertion-Base of proximal phalanx of digit 1

Innervation-Radial n.

Action-Extends the proximal phalanx of the thumb at the metacarpophalangeal joint; also extends carpometacarpal joint

Question 10

Extensor pollicis longus

Answer 10

Origin-Middle 1/3 of posterior ulna and interosseous membrane

Insertion-Base of distal phalanx of digit 1

Innervation-Radial n.

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

Question 11

Extensor indicis

Answer 11

Origin-Distal 1/3 of posterior ulna and interosseous membrane

Insertion-Extensor expansion of digit 2

Innervation-Radial n.

Action-Extends proximal phalanx of digit 2, also extends hand at wrist