Posterior Forearm

Question 1

What are the muscles of the posterior forearm?

Answer 1

Superficial: brachioradialis, extensor carpi radialis longs, extensor carpi radialis breves, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris
Deep: supinator, extensor indicis
Outcropping Thumb: abductor pollicis longs, extensor pollicis breves, extensor pollicis longs

Question 2

Locate the areas of the skin associated with a single spinal segment/nerve (dermatome).

Answer 2

C5 - deltoid tuberosity
C6 - thumb 
C7 - index finger
C8 - 5th digit (pinky)
T1 - medial aspect of forearm just below medial condyle

Question 3

Identify structures on the supinator muscle.

Answer 3

Kenhub

Question 4

Name the actions and innervations of the brachioradialis.

Answer 4

C5-C6
Attachments: from lateral supracondylar ridge of the humerus to the distal radius lateral to the styloid process
Actions: flex the elbow
Innervation: radial n.

Question 5

Name the actions and innervations of the extensor carpi radialis longus.

Answer 5

C6-C8
Attachments: lateral supracondylar ridge of the humerus to the base of the 2nd metacarpal
Actions: extends and abducts hand at wrist (radial deviation) and assists in flexion of the elbow
Innervation: radial n.

Question 6

Name the actions and innervations of the extensor carpi radialis brevis.

Answer 6

C6-C8
Attachments: lateral epicondyle of the humerus to the base of the 3rd metacarpal
Action: extends and abducts hand at wrist (radial deviation)
Innervation: radial n.

Question 7

Name the actions and innervations of the extensor digitorum.

Answer 7

C6-C8
Attachments: lateral epicondyle of the humerus to the extensor expansions of digits 2-5
Actions: extends phalanges (primarily at metacarpophalangeal, secondarily at interphalangeal) and hand at wrist
innervation: radial n.

Question 8

Name the actions and innervations of the extensor digiti minimi.

Answer 8

C7-C8
Attachments: lateral epicondyle of humerus to the digital expansion of the 5th digit
Actions: extends 5th digit (metacarpophalangeal and interphalangeal)
Innervation: radial n.

Question 9

Name the actions and innervations of the extensor carpi ulnaris.

Answer 9

C6-C8
Attachments: lateral epicondyle of the humerus to the base of the 5th metacarpal
Actions: extends and adduction hand at wrist (ulnar deviation)
Innervation: radial n.

Question 10

Name the actions and innervations of the supinator.

Answer 10

C5-C6
Attachments: lateral epicondyle of the humerus, radial collateral ligament and supinator crest of the ulna to the lateral surface of the proximal radius
Actions: supinates forearm
Innervation: radial n.

Question 11

Name the actions and innervations of the extensor indicis.

Answer 11

C7-C8
Attachments; posterior surface of the ulna and interosseous membrane to the digital expansion of the 2nd digit
Actions: extends 2nd digit (metacarpophalangeal and interphalangeal)
Innervation: radial n.

Question 12

Name the actions and innervations of the abductor pollicis longus.

Answer 12

C6-C8
Attachments: proximal posterior radius, ulna, and interosseous membrane to the base of the 1st metacarpal and trapezium
Action: abducts and extends thumb at carpometacarpal joint and abducts hand at wrist (radial deviation)
Innervation: radial n.

Question 13

Name the actions and innervations of the extensor pollicis brevis.

Answer 13

C6-C8
Attachments; posterior radial surface and interosseous membrane to the base of the 1st proximal phalanx
Actions: extends thumb (metacarpophalangeal) and extends and abducts CMC joint
Innervation: radial n.

Question 14

Name the actions and innervations of the extensor pollicis longus.

Answer 14

C6-C8
Attachments: middle 1/3 of the posterior surface of the ulna and interosseous membrane to the base of the 1st distal phalanx
Actions: extends thumb (CMC and metacarpophalangeal and interphalangeal)
Innervation: radial n.