ANAT: Posterior forearm and Hand

Question 1

Innervation of posterior forearm muscles

Answer 1

Radial n.

Question 2

Superficial layer muscles

Answer 2

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

Question 3

Deep layer muscles

Answer 3

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

Question 4

Brachioradialis [O]

Answer 4

Lateral supracondylar ridge of the humerus

Question 5

Brachioradialis [I]

Answer 5

Distal radius, near styloid process

Question 6

Brachioradialis [A]

Answer 6

Flexes the forearm, partially supinates from fully pronated position

Question 7

Extensor carpi radialis longus [O]

Answer 7

Lateral supracondylar ridge

Question 8

Extensor carpi radialis longus [I]

Answer 8

Base of second metacarpal

Question 9

Extensor carpi radialis longus [A]

Answer 9

Extends and abducts the hand, weakly flexes forearm

Question 10

Extensor carpi radialis brevis [O]

Answer 10

Lateral epicondyle of humerus

Question 11

Extensor carpi radialis brevis [I]

Answer 11

Base of third metacarpal

Question 12

Extensor carpi radialis brevis [A]

Answer 12

Extends and abducts the hand; assists in forearm extension

Question 13

Extensor digitorum [O]

Answer 13

Lateral epicondyle

Question 14

Extensor digitorum [I]

Answer 14

Tendons to digits II, III, IV, and often (not always) V. Base of proximal phalanx, splits into central band to base of middle phalanx, and then then two side bands (collateral bands) to the distal phalanx

Question 15

Extensor digitorum [A]

Answer 15

Extends MCP joint, PIP, and DIP joints. Assists in extending hand and forearm

Question 16

Extensor digiti minimi [O]

Answer 16

Lateral epicondyle

Question 17

Extensor digiti minimi [I]

Answer 17

Joins ED tendon of Digit V

Question 18

Extensor digiti minimi [A]

Answer 18

Extension of MCP, PIP, and DIP joints of digit V, minorly assists in hand an forearm extension

Question 19

Extensor carpi ulnaris [O]

Answer 19

Lateral epicondyle and posterior border of the Ulna

Question 20

Extensor carpi ulnaris [I]

Answer 20

Base of the fifth metacarpal

Question 21

Extensor carpi ulnaris [A]

Answer 21

Extends and adducts the hand; assists in extension of the forearm

Question 22

Anconeus [O]

Answer 22

Posterior lateral epicondyle

Question 23

Anconeus [I]

Answer 23

lateral side of the proximal Ulna; including Olecranon process

Question 24

Anconeus [A]

Answer 24

Assists triceps in extending the forearm, stabalizes the elbow joint; abducts the ulna during pronation

Question 25

Supinator [O]

Answer 25

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

Question 26

Supinator [I]

Answer 26

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

Question 27

Supinator [A]

Answer 27

Supinates the forearm by swiveling radius, less powerful supinator than biceps brachii, unless fully extended.

Question 28

Outcropping (interosseous) muscles

Answer 28

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

Question 29

Outcropping (interosseous) muscles [O]

Answer 29

Posterior side of the interosseous membrane, and adjacent parts of the ulna and radius

Question 30

Abductor pollicis longus [I]

Answer 30

Base of the metacarpal 1, laterally

Question 31

Abductor pollicis longus [A]

Answer 31

Abducts and extends the 1st carpometacarpal joint and abducts the hand

Question 32

Extensor pollicis brevis [I]

Answer 32

Base of the proximal phalanx of the thumb

Question 33

Extensor pollicis brevis [A]

Answer 33

Extends CM and MCP joints of the thumb and abducts the hand

Question 34

Extensor pollicis longus [I]

Answer 34

Base of the distal phalanx of the thumb

Question 35

Extensor pollicis longus [A]

Answer 35

Extends the CM, MCP, and IP joint of the thumb. Assists in extending the hand

Question 36

Extensor indicis [I]

Answer 36

Joins ED tendon to digit II

Question 37

Extensor indicis [A]

Answer 37

Extends, MCP, PIP, and DIP joints of digit II. Slightly assists in extending the hand

Question 38

Anatomical Snuffbox

Answer 38

Area between the Extensor pollicis longus tendon and the Extensor pollicis brevis tendon *Clinical: fractured Scaphoid is tender here.

Question 39

Lateral epicondylitis

Answer 39

(Elbow tendinitis) Due to excessive use of the superficial extensor muscles of the forearm. - Inflammation of the periosteum of the lateral epicondyle and the origin of the superficial extensor mm. * Pain conveyed by the superficial branch of the radial n. - radiates inferiorly down posterior forearm.

Question 40

Mallet/ Baseball finger ("Jammed" finger)

Answer 40

Due to avulsion of the insertion of the extensor tendon on the distal phalanx; resulting from forceful flexion of the DIP during extension. *Presentation: extension of all joints except the DIP which remains flexed.

Question 41

Synovial cyst of the wrist

Answer 41

Cysts of mucinous fluid called "ganglion" non-tender swellings that appear on dorsal wrist -- communicates with synovial sheaths