Extensors of Forearm & Wrist

Question 1

What 3 muscles extend the wrist?

Answer 1

1) Extensor carpi radialis longus
2) Extensor carpi radialis brevis
3) Extensor carpi ulnaris

Question 2

What 3 muscles extend the digits (except thumb)?

Answer 2

1) Extensor digitorum
2) Extensor indicis
3) Extensor digiti minimi

Question 3

What 3 muscles extend the thumb?

Answer 3

1) Abductor pollicus longus
2) Extensor pollicus longus
3) Extensor pollicus brevis

Question 4

What is the most commonly fractured carpal bone?

Answer 4

Scaphoid

Question 5

What extends the IP joints (DIP + PIP)?

Answer 5

Extensor tendon

Question 6

What muscles extend the MCP joints?

Answer 6

Extensor digitorum

Question 7

What muscle is part of the extensor/supinator compartment but actually functions as an elbow flexor?

Answer 7

Brachioradialis

Question 8

What is the common attachment site for the superficial forearm extensor muscles?

Answer 8

Lateral epicondyle

Question 9

What are the 6 superficial extensor muscles?

Answer 9

1) Brachioradialis
2) Extensor carpi radialis longus
3) Extensor carpi radialis brevis
4) Extensor carpi ulnaris
5) Extensor digitorum
6) Extensor digiti minimi

Question 10

What are the 5 deep extensor muscles?

Answer 10

1) Supinator
2) Abductor pollicis longus
3) Extensor pollicis brevis
4) Extensor pollicis longus
5) Extensor indicis

Question 11

Brachioradialis (origin + insertion)

Answer 11

Origin:
- Lateral supracondylar ridge of humerus

Insertion:
- Lateral surface of distal end of radius

Question 12

Brachioradialis (function + innervation)

Answer 12

Function:

1) Flex FA
2) Pronate/supinate

Innervation: 
Radial nerve (C6) (C5, C7)

Question 13

Supinator (origin + insertion)

Answer 13

Origin:
-Lateral epicondyle of humerus, radial collateral and annular ligaments, supinator fossa, crest of ulna

Insertion:
- Lateral, posterior and anterior surfaces of radius

Question 14

Supinator (function + innervation)

Answer 14

Function:
- Supinate FA

Innervation: 
Radial nerve (C6) (C5)

Question 15

What nerve is the continuation of the deep branch of the radial nerve?

Answer 15

Posterior interosseous nerve (PIN)

Question 16

Posterior interosseous nerve (PIN)

Answer 16

Continuation of deep branch of radial nerve

• Runs in between superficial + deep parts of supinator

Question 17

What fascia holds all the extensor tendons?

Answer 17

Extensor retinaculum

Question 18

Name all extensor tendon compartments (+ contents)

Answer 18

1) Extensor pollicus brevis + abductor pollicus longus
2) Extensor carpi radialis longus + extensor carpi radialis brevis
3) Extensor pollicus longus
4) Extensor digitorum + extensor indicis
5) Extensor digiti minimi
6) Extensor carpi ulnaris

Question 19

What are the contents of the anatomical snuffbox?

Answer 19

1) Radial artery (superficial)
2) Scaphoid bone (deep)
3) Superficial radial nerve (“roof”)

Question 20

What are the boundaries of the anatomical snuffbox?

Answer 20

Extensor pollicus longus (medial)
Extensor pollicus brevis (lateral)

*Abductor pollicus longus lies more lateral to EPB

Question 21

What nerve innervates the palmar + dorsal interossous muscles?

Answer 21

Ulnar nerve

Question 22

What muscles attach to the dorsal “hood”?

Answer 22

1) Extensor digitorum
2) Lumbricals
3) Palmar interosseous
4) Dorsal interosseous

Question 23

What nerve innervates all the extensor muscles?

Answer 23

Radial nerve

Question 24

What bony structure does extensor pollicis longus loop around to angle towards the thumb?

Answer 24

Lister’s tubercle (dorsal tubercle) of radius

Question 25

Where do the lumbricals originate from?

Answer 25

Tendons of flexor digitorum profundus

Question 26

Brachioradialis (origin + insertion)

Answer 26

Origin: -Lateral supracondylar ridge of humerus Insertion: -Lateral surface of distal end of radius

Question 27

Brachioradialis (function + innervation)

Answer 27

Function: - Flex forearm - Pronate/supinate Innervation: - Radial nerve (C6) (C5,C7)

Question 28

Supinator (origin + insertion)

Answer 28

Origin: - Lateral epicondyle of humerus - Radial collateral and annular ligaments - Supinator fossa - Crest of ulna Insertion: - Lateral, posterior and anterior surfaces of radius

Question 29

Supinator (function + innervation)

Answer 29

Function: - Supinate forearm Innervation: - Radial nerve (C6) (C5)

Question 30

Which nerve runs in between the superficial + deep parts of the supinator muscle?

Answer 30

Radial nerve

Question 31

What branches does the radial nerve give off around the region of the lateral epicondyle?

Answer 31

1) Superficial branch of radial nerve 2) Posterior interosseous nerve (PIN) * Also known as deep branch of radial nerve

Question 32

Which muscle extends the MCP joints?

Answer 32

Extensor digitorum

Question 33

Which muscles extend the DIP + PIP joints?

Answer 33

Extensor tendon facilitated mainly by lumbrical muscles

Question 34

What symptom typically presents due to extensor tendon injury?

Answer 34

Mallet finger

Question 35

Mallet finger

Answer 35

- Due to rupture/avulsion of extensor tendon - Finger presents in flexed state - Unable to extend finger

Question 36

What separates the ulna bone from the carpal bones?

Answer 36

Triangular fibrocartilage complexx (TFCC)

Question 37

What are the carpal bones bordered by laterally + medially?

Answer 37

Radial + ulnar collateral ligaments

Question 38

What kind of a joint if the CMC joint of the thumb?

Answer 38

Saddle joint

Question 39

What muscles flex the hand at the wrist?

Answer 39

1) Flexor carpi radialist 2) Flexor carpi ulnaris 3) Palmaris longus

Question 40

Which muscles flex the digits?

Answer 40

1) Flexor digitorum superficialis 2) Flexor digitorum profundus 3) Flexor pollicis longus

Question 41

What muscles extend the hand at the wrist?

Answer 41

1) Flexor carpi radialis longus 2) Flexor carpi radialis brevis 3) Flexor carpi ulnaris

Question 42

Which muscles extend the digits (except the thumb)?

Answer 42

1) Extensor digitorum 2) Extensor indicis 3) Extensor digiti minimi

Question 43

Which muscles extend the thumb?

Answer 43

1) Abductor pollicis longus 2) Extensor pollicis brevis 3) Extensor pollicis longus

Question 44

Which muscles rotate the radius on the ulna?

Answer 44

1) Pronator teres 2) Pronator quadratus 3) Supinator

Question 45

Which muscle is actually a stronger supinator than the supinator muscle?

Answer 45

Biceps brachii