Posterior Forearm & Hand

Question 1

What are the superficial layer of muscles for the posterior compartment of the forearm?

Answer 1

Brachioradialis, Extensor carpi radialis longus, Extensor carpi radialis brevis, Extensor digitorum, Extensor digiti minimi, Extensor carpi ulnaris, Anconeus

Question 2

Brachioradialis origin

Answer 2

Lateral supracondylar ridge of humerus

Question 3

Brachioradialis insertion

Answer 3

Distal end of the radius near the styloid process

Question 4

Brachioradialis actions

Answer 4

Flexes the forearm. It also partially supinates from a fully pronated position

Question 5

Posterior muscle group of the forearm is innervated by what nerve?

Answer 5

Radial nerve

Question 6

Posterior muscle group of the forearm is supplied by what?

Answer 6

Posterior interosseous artery

Question 7

Extensor carpi radialis longus origin

Answer 7

Lateral supracondylar ridge

Question 8

Extensor carpi radialis longus insertion

Answer 8

Base of second metacarpal

Question 9

Extensor carpi radialis longus actions

Answer 9

Extends and abducts the hand. Weakly flexes the forearm

Question 10

Extensor carpi radialis brevis origin

Answer 10

Lateral epicondyle of the humerus

Question 11

Extensor carpi radialis brevis insertion

Answer 11

Base of 3rd metacarpal

Question 12

Extensor carpi radialis brevis actions

Answer 12

Extends and weakly abducts the hand. Assists in extending the forearm.

Question 13

Extensor digitorum origin

Answer 13

Lateral epicondyle

Question 14

Extensor digitorum insertion

Answer 14

Tendons go to digits 2, 3, 4, and often 5. Each tendon inserts on the base of the proximal phalanx and then splits into a central band to the base of the middle phalanx and two side bands (collateral bands) to the base of the distal phalanx

Question 15

Extensor digitorum actions

Answer 15

Extension at the metacarpophalangeal and interphalangeal joints (PIP, DIP). Over 180 degrees of MCP joint, extending IP joints need lumbricals and interossei. Assists in extending the wrist and forearm.

Question 16

Extensor digiti minimi origin

Answer 16

Lateral epicondyle

Question 17

Extensor digiti minimi insertion

Answer 17

Joins extensor digitorum of 5th finger

Question 18

Extensor digiti minimi actions

Answer 18

Extension at the metacarpophalangeal and interphalangeal joints (PIP, DIP) on digit 5. Over 180 degrees of MCP joint, extending IP joints need lumbricals and interossei. Assists in extending the wrist and forearm.

Question 19

Extensor carpi ulnaris origin

Answer 19

Lateral epicondyle and posterior border of the ulna

Question 20

Extensor carpi ulnaris insertion

Answer 20

Base of the 5th metacarpal

Question 21

Extensor carpi ulnaris actions

Answer 21

Extends and adducts the wrist. Assists in extending the forearm.

Question 22

Anconeus origin

Answer 22

Posterior side of the lateral epicondyle

Question 23

Anconeus insertion

Answer 23

Lateral side of the proximal part of the ulna, including the olecranon process

Question 24

Anconeus actions

Answer 24

Assists triceps in extending the forearm. Stabilizes the elbow joints. Abducts the ulna during pronation

Question 25

What are the deep layer muscles of the posterior forearm?

Answer 25

Supinator, Abductor pollicis longus, Extensor pollicis brevis, Extensor pollicis longus, Extensor indicis

Question 26

Supinator origin

Answer 26

Lateral epicondyle, radial collateral ligament of the elbow, and lateral side of the proximal part of the ulna

Question 27

Supinator insertion

Answer 27

Spirals around the proximal part of the radius to insert on its posterior, lateral, and anterior sides

Question 28

Supinator actions

Answer 28

Supinates forearm by swiveling radius; less powerful supination than biceps brachii unless forearm is extended

Question 29

Abductor pollicis longus origin

Answer 29

Posterior side of the interosseous membrane and adjacent parts of the radius and/or ulna

Question 30

Abductor pollicis longus insertion

Answer 30

Base of the 1st metacarpal, laterally

Question 31

Abductor pollicis longus actions

Answer 31

Abducts and extends the 1st carpometacarpal (CM) joint and abducts the hand

Question 32

Extensor pollicis brevis origin

Answer 32

Posterior side of the interosseous membrane and adjacent parts of the radius and/or ulna

Question 33

Extensor pollicis brevis insertion

Answer 33

Base of the proximal phalanx of the thumb

Question 34

Extensor pollicis brevis actions

Answer 34

Extends CM and MCP joints of thumb and abducts the hand

Question 35

Extensor pollicis longus origin

Answer 35

Posterior side of the interosseous membrane and adjacent parts of the radius and/or ulna

Question 36

Extensor pollicis longus insertion

Answer 36

Base of the distal phalanx of the thumb

Question 37

Extensor pollicis longus actions

Answer 37

Extends all joints of the thumb (CM, MCP, IP). Also extends the hand. Tendon bends around the dorsal tubercle of the radius

Question 38

Extensor indicis origin

Answer 38

Posterior side of the interosseous membrane and adjacent parts of the radius and/or ulna

Question 39

Extensor indicis insertion

Answer 39

Joins extensor digitorum tendon to index finger

Question 40

Extensor indicis actions

Answer 40

Extension at the metacarpophalangeal and interphalangeal joints (PIP, DIP) on digit 2. Over 180 degrees of MCP joint, extending IP joints need lumbricals and interossei. Assists in extending the wrist and forearm.

Question 41

What muscles are part of the outcropping muscles?

Answer 41

Abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis, anatomical snuffbox. Their tendons emerge (outcrop) between tendons and superficial muscles