Extensor Forearm Compartment

Question 1

what are the superficial muscles of the Extensor forearm compartment?

Answer 1

1. brachioradialis
2. extensor carpi radialis longus
3. extensor carpi radialis brevis
4. extensor digitorum communis
5. extensor digitorum minimi
6. extensor carpi ulnaris

Question 2

what is the action of the brachiradialis?

what is its significance?

Answer 2

Both anterior and posterior muscle and therefore it has 2 actions

Actions: during semipronation, it can flex, during full supination, it can extend

Question 3

what is the action of the Extensor carpi radialis longus?

Answer 3

extends hand radially (laterally)

Question 4

what is the action of the Extensor carpi radialis brevis?

Answer 4

extends hand radially (laterally)

Question 5

what is the action of the Extensor digitorum communis?

Answer 5

Extends the middle four digits

Question 6

what is the action of the Extensor digitorum minimi?

Answer 6

extend pinky

Question 7

what is the action of the Extensor carpi ulnaris?

Answer 7

extends wrist ulnarly (medially)

Question 8

what are the deep muscles of the extensor forearm compartment and their actions?

Answer 8

1. supinator: supinate forearm
2. extensor indicis: extend index finger
3. abductor pollicis longus: abduct thumb
4. extensor pollicis longus: extend hand medially
5. extensor pollicis brevis: extend hand laterally

Question 9

what is the space between tendons of extensor pollicis longus + extensor pollicis brevis?

Answer 9

anatomical snuffbox

Question 10

what makes up the floor of the anatomical snuffbox?

Answer 10

scaphoid bone (most commonly fractured bone in hand area)

Question 11

how does the radial artery travel to the snuffbox?

Answer 11

Radial artery is located at the wrist between the tendons of abductor policis longus laterally and flexor carpi radialis medially
• Travels deep to the abductor pollicis longus to get to the snuff box

Question 12

how does the radial nerve travel in the extensor forearm compartment?

Answer 12

1. Enters posterior arm and runs between 3 heads of the triceps brachii
2. Travels laterally on the musculospiral groove alongside the deep brachial artery (profunda brachii)
3. Travels anterior to the lateral epicondyle as it enters the forearm
4. Before it enters forearm it splits in to 2

Question 13

what does the radial nerve split into?

Answer 13

1. superficial radial nerve
2. deep radial nerve
3. posterior interosseus nerve

Question 14

how does the superficial radial nerve travel?

what does it innervate?

Answer 14

travels directly beneath skin all the way down to the lateral aspect of the dorsal hand
➢ Innervates the skin of the lateral dorsal aspect of the hand (excluding the web aka the region of exclusivity) making it a dermatomal n.

Question 15

how does the deep radial nerve travel?

what does it become?

Answer 15

travels deep towards bone
➢ Penetrates through the supinator (deepest muscle in pos. forearm)
➢ Emerges and becomes the posterior interosseous n.

Question 16

what does the posterior interosseus nerve supply

Answer 16

muscles of the hand