Antebrachium Posterior Compartment

Question 1

Brachioradialis

Answer 1

Superficial Layer
O: proximal two-thirds of supracondylar ridge of humerus
I: lateral surface of distal end of radius proximal to styloid process
INNE: Radial n. (C5-C7)
Action: Relatively weak FLX of antebrachium - MAX when forearm in pronation

Question 2

Extensor Carpi Radialis Longus

Answer 2

Superficial Layer
O: lateral supracondylar ridge
I:  Dorsal aspect of base of 2nd MC
INNE: Radial n. (C6-C7)
Action: EXT and ABD hand at MC joint (active during clenching)

Question 3

Extensor Carpi Radialis Brevis

Answer 3

Superficial Layer
O: Lateral epicondyle of humerus
I: Dorsal aspect of base of 3rd MC
Action: AXT and ABD hand at MC joint (active during clenching)
INNE: Deep Radial n. (C7, C8)

Question 4

Extensor Digitorum

Answer 4

Superficial Layer
O: Lateral epicondyle of humerus
I: Extensor expansions of medial four digits
Action: EXT medial four digits (primarily) at MCP joints and (secondary) IP joints
INNE: Deep Radial n. (C7, C8)

Question 5

Extensor Digiti Minimi

Answer 5

Superficial Layer
O: Lateral Epicondyle of humerus
I: Extensor expansion of 5th digit
Action: EXT 5th digit at MCP and IP joints
INNE: Deep Radial n. (C7, C8)

Question 6

Extensor Carpi Ulnaris

Answer 6

Superficial Layer
O: Lateral epicondyle of humerus and posterior border of ulna via shred aponeurosis
I: Dorsal aspect of base of 5th MC
Action: EXT and ADD wrist 
INNE: Deep Radial n. (C7, C8)

Question 7

Supinator

Answer 7

Deep Layer
O: Lateral epicondyle of humerus/ radial collateral and anular ligaments/ superior ulna and crest of ulna
I: Lateral, posterior, and anterior surfacesof proximal radius
INNE: Deep branch of radial n. (C7-C8)
Action: supinates forearm

Question 8

Extensor Indicis

Answer 8

Deep Layer
O: Posterior surface of distal third of ulna and interosseous membrane
I: Extensor expansion of 2nd digit
INNE: Posterior interosseous n. (C7, C8), continuation of deep interosseous
Action: EXT 2nd digit; helps extend hand and wrist.

Question 9

Abductor Pollicis Longus

Answer 9

Deep Layer
O:posterior surface of proximal halves of ulna, radius, and interosseous membrane
I: base of 1st MC
Action: ABD thumb and EXT CMC joint
INNE: Posterior Interosseous nn. of Deep Radial

Question 10

Extensor Pollicis Longus

Answer 10

Deep Layer
O: Posterior surface of middle third of ulna and interosseous membrane
I: Dorsal aspect of base of distal phalanx of thumb.
Action: EXT distal phalanx of thumb at IP joint, EXT MCP and CMC joints
INNE: Posterior Interosseous nn. of Deep Radial

Question 11

Extensor Pollicis Brevis

Answer 11

Deep Layer
O: Posterior surface of distal third of radius and interosseous membrane
I: Dorsal aspect of base of proximal thumb
Action: EXT proximal phalanx of thumb at MC joint and CMC joint.
INNE: Posterior Interosseous nn. of Deep Radial