MSK - Muscles of the Posterior Forearm

Question 1

Name the superficial muscles of the posterior forearm (7)

Answer 1

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

Question 2

What is the origin of brachioradialis?

Answer 2

Proximal aspect of the lateral supraepicondylar ridge of the humerus

Question 3

Where does brachioradialis insert?

Answer 3

• Distal end of the radius

- Proximal to the radial styloid process

Question 4

What is the innervation of brachioradialis?

Answer 4

Radial nerve (C5, C6)

Question 5

What are the actions of brachioradialis?

Answer 5

• Flexion of the forearm at the elbow

assists biceps brachii

Question 6

What is the blood supply of brachioradialis?

Answer 6

Radial recurrent artery

Question 7

What is the origin of extensor carpi radialis longus?

Answer 7

Supracondylar ridge

Question 8

Where does extensor carpi radialis longus insert?

Answer 8

Tendon attaches to metacarpal bone 2

Question 9

What is the innervation of extensor carpi radialis longus?

Answer 9

Radial nerve (C6, C7)

Question 10

What are the actions of extensor carpi radialis longus?

Answer 10

• Extension of the wrist

- Radial deviation of the hand at the wrist

Question 11

What is the origin of extensor carpi radialis brevis?

Answer 11

Lateral epicondyle of the humerus

Question 12

Where does extensor carpi radialis brevis insert?

Answer 12

Tendon attaches to metacarpal bone 3

Question 13

What is the innervation of extensor carpi radialis brevis?

Answer 13

Radial nerve (C6, C7)

Question 14

What are the actions of extensor carpi radialis brevis?

Answer 14

• Extension of the wrist

- Radial deviation of the hand at the wrist

Question 15

What is the origin of extensor digitorum?

Answer 15

Lateral epicondyle of the humerus

Question 16

Where does extensor digitorum insert?

Answer 16

• Tendon splits into four in the distal forearm

- Inserts into extensor hood of each finger

Question 17

What is the innervation of extensor digitorum?

Answer 17

Deep branch of radial nerve (C6, C8)

Question 18

What are the actions of extensor digitorum?

Answer 18

Extension of digits 2-4 at MCP and IP joints

Question 19

What is the blood supply of extensor digitorum?

Answer 19

Posterior interosseous artery

Question 20

What is the blood supply of extensor carpi radialis/brevis?

Answer 20

Radial artery

Question 21

What is the origin of extensor digiti minimi?

Answer 21

Lateral epicondyle of the humerus

Question 22

Where does extensor digiti minimi insert?

Answer 22

Base of 5th metacarpal

Question 23

What is the innervation of extensor digiti minimi?

Answer 23

Radial nerve (C7, C8)

Question 24

What are the actions of extensor digiti minimi?

Answer 24

• Extension of the wrist

- Ulnar deviation

Question 25

What is the blood supply of extensor digiti minimi?

Answer 25

Posterior interosseous artery

Question 26

What is the origin of anconeus?

Answer 26

Lateral epicondyle of the humerus

Blends with triceps brachii so is often undistinguishable

Question 27

Where does anconeus insert?

Answer 27

Posterior and lateral part of the olecrannon

Question 28

What is the innervation of anconeus?

Answer 28

Radial nerve (C7, C8)

Question 29

What are the actions of anconeus?

Answer 29

• Moves ulna during pronation

- Extension of the forearm at the elbow joint

Question 30

What is the blood supply of anconeus?

Answer 30

Middle collateral artery from the profunda brachii artery

Question 31

How can the function of extensor digitorum be tested?

Answer 31

• Pronate the forearm
• Extend fingers against resistance

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