[Muscles] Extensors of forearm

Question 1

Brachioradialis

Answer 1

O: Lateral supracondylar ridge of the humerus
Ins: lateral side of distal radius
Inn: Radial Nerve
Bs: Radial Artery
Action: flexes forearm in mid-pronation 
Ext forearm at elbow

Question 2

Extensor carpi radialis longus

Answer 2

O: Lateral supracondylar ridge of the humerus
Ins: dorsal surface at base of 2nd MC
Inn: Radial N
Bs: Radial A
Action: ABD/Ext hand @ wrist
Ext forearm @ elbow

Question 3

Extensor carpi radialis brevis

Answer 3

O: lateral epicondyle of the humerus
Ins: Base of 3rd MC
Inn: Deep branch of radial N 
Bs: Radial A 
Action: ABD/Ext hand @ wrist 
Ext forearm @ elbow

Question 4

Extensor digitorum

Answer 4

O: lateral epicondyle of the humerus
Ins: extensor hood expansion of medial 4 digits
Inn: Posterior interosseous N
Bs: posterior interosseous A
Action: ext 4 digits, ext wrist, ext forearm at elbow

Question 5

Extensor digiti minimi

Answer 5

O: Lateral epicondyle of the humerus
Ins: extensor expansion of the fifth digit
Inn: Posterior interosseous N
Bs: Recurrent interosseous A
Action: ext 5th digit, ext forearm at elbow

Question 6

Extensor Carpi Ulnaris

Answer 6

O: lateral epicondyle of the humerus, posterior border of the ulna
Ins: medial side at base of 5th MC
Inn: Posterior interosseous N
Bs: Ulnar A
Action: ADD/ext hand at wrist
Ext forearm at elbow

Question 7

Extensor Inidicis

Answer 7

O: posterior surface of ulna, interosseous membrane
Ins: hood of extensor expansion of 2nd digit
Inn: Posterior interosseous N
Bs: Posterior interosseous A
Action: Extends all joints of index finger

Question 8

Abductor Pollicis Brevis

Answer 8

O: posterior surface of ulna and radius, interosseous membrane
Ins: Lateral side of base of first MC
Inn: Posterior interosseous N
Bs: Posterior interosseous A
Action: Ext, ABD, laterally rotate thumb at CMC

Question 9

Extensor pollicis Brevis

Answer 9

O: posterior surface of radius, interosseous membrane
Ins: Dorsal surface of base of proximal phalanx of thumb
Inn: Posterior interosseous N
Bs: Posterior interosseous A
Action: Ext proximal phalanx of thumb at MCP jt

Question 10

Extensor pollicis longus

Answer 10

O: posterior border of ulna, interosseous membrane
Ins: Dorsal surface of base of distal phalanx of the thumb
Inn: Posterior interosseous N
Bs: Posterior interosseous A
Action: Ext IP, MCP, and CMC jts

Question 11

Supinator

Answer 11

O: lateral epicondyle of the humerus 
Ins: lateral radius anterior to oblique line
Inn: Posterior interosseous N
Bs: Posterior interosseous A
Action: Supination

Question 12

Anconeus

Answer 12

O: lateral epicondyle of the humerus 
Ins: olecranon and posterior proximal surface of ulna 
Inn: radial N
Bs: Deep brachial A
Action: ABD ulna in pronation,
Accessory extension of elbow

Question 13

Triceps Brachii

Answer 13

O: Long head - infraglenoid tubercle of the scapula
Lateral and medial heads - Posterior surface of the humerus
Ins: Olecranon of the ulna via common tendon
Inn: Radial N
Bs: Deep brachial A
Action: LH extends arm at GHJ
extends forearm at elbow