Posterior Forearm and Dorsum of Hand

Question 1

Anconeus

• Attachments
• Function
• Innervation

Answer 1

• Lateral epicondyle of humerus to olecranon of ulna
• Extension of the elbow
• Radial nerve (C7-8(T1))

Question 2

Brachioradialis

• Attachments
• Function
• Innervation

Answer 2

• Distal humerus to radius proximal to styloid process
• Flexion of the elbow, especially when forearm is in the semi-prone position
• Radial nerve (C5-C7) Despite being a flexor muscle

Question 3

Extensor carpi radialis (longus and brevis)

• Longus attachments
• Brevis attachments
• Extension for both
• Longus innervation
• Brevis innervation

Answer 3

• From distal humerus to base of 2nd metacarpal
• From lateral epicondyle of the humerus to the base of the 3rd metacarpal
• Wrist extension and abduction
• Radial nerve (C6+C7) - pre-division
• Radial nerve (C7+C8) - posterior interosseous

Question 4

Extensor Carpi Ulnaris

• Attachments
• Function
• Innervation

Answer 4

• Lateral epicondyle of the humerus to the base of the 5th metacarpal
• Wrist extension and adduction
• Radial nerve (C7+C8) - Posterior interosseous

Question 5

Extensor Digitorum

• Attachments
• Function
• Innervation

Answer 5

• Lateral epicondyle of the humerus to the dorsal expansion of digits 2-5
• Extension of MCP, but also PIP and DIP extension of digits 2-5
• Radial nerve (C7+C8) - Posterior interosseous

Question 6

Extensor Digiti Minimi

• Attachments
• Function
• Innervation

Answer 6

• Lateral epicondyle of the humerus to the dorsal expansion of the 5th digit (pinkie)
• MCP, PIP and DIP extension of the little finger
• Radial nerve (C7+C8) - Posterior interosseous

Question 7

Extensor Indices

• Attachments
• Function
• Innervation

Answer 7

• Posterior surface of ulna to dorsal expansion of digit 2
• MCP, PIP and DIP extension of the index finger, plus wrist extension
• Radial nerve (C7+8) - Posterior interosseous

Question 8

Extensor Pollicis Longus

• Attachments
• Function
• Innervation

Answer 8

• Ulna and interosseous membrane to the base of the distal phalanx of the thumb
• CMC, MCP and IP extension of the thumb. Also extends wrist.
• Radial nerve (C7+C8) - posterior interosseous

Question 9

Extensor Pollicis Brevis

• Attachments
• Function
• Innervation

Answer 9

• Radius and interosseous membrane to the base of the proximal phalanx of the thumb
• Carpometacarpal and MCP thumb joint extension. Extends wrist.
• Radial nerve (C7+C8) - Posterior interosseous

Question 10

Abductor Pollicis Longus

• Attachments
• Function
• Innervation

Answer 10

• Radius, interosseous membrane and ulna to the base of the 1st metacarpal
• Abducts thumb and extends it at the carpometacarpal joint. Also extends the wrist.
• Radial nerve (C7+C8) - Posterior interosseous

Question 11

Supinator

• Attachments
• Function
• Innervation
• Radial Nerve

Answer 11

• Crest of ulna, the lateral epicondyle of the humerus, and the radial collateral and annular ligaments of radius to the lateral radius (in the proximal 1/3)
• Supination of forearm (rotation of radius)
• Radial nerve (C7+C8) - Deep/posterior interosseous
• Passes through the lamina of the supinator

Question 12

Interosseous Arteries

Answer 12

Question 13

Overview of Dorsum of Hand

Answer 13