4.1.3. Extensor and Abductor Muscles of the Thumb

Question 1

What are the Muscles of the Posterior Forearm commonly known as?

Answer 1

Extensor Muscles

Question 2

What is the General Function of these Muscles?

Answer 2

To Produce Extension at the Wrists and Fingers

Question 3

Which Nerve innervates the Muscles of the Posterior Forearm?

Answer 3

The Radial Nerve

Question 4

1. How many groups can the Muscles of the Posterior Forearm be Divided into, Anatomically?
2. What are they?

Answer 4

1. 2
2. a) Superficial Muscles of the Posterior Forearm
3. b) Deep Muscles of the Posterior Forearm

Question 5

1. How many groups can the Muscles of the Posterior Forearm be Divided into, Functionally?
2. What are they?

Answer 5

1. 3
2. a) Muscles which Extend and Abduct / Adduct the Hand at the Wrist Joint
3. b) Muscles which Extend the Medial 4 Digits
4. c) Muscles which Extend or Abduct the Thumb

Question 6

What are the 3 Muscles which Extend of Abduct the Thumb?

Answer 6

1. Abductor Pollicis Longus
2. Extensor Pollicis Brevis
3. Extensor Pollicis Longus

Question 7

Is the Abductor Pollicis Longus an Anatomically Superficial or Deep Muscle of the Posterior Forearm?

Answer 7

Deep

Question 8

Where is the Abductor Pollicis Longus located, in relation to the Supinator Muscle?

Answer 8

Immediately Distal to the Supinator Muscle

Question 9

What does the Tendon of the Abductor Pollicis Longus contribute to in the Hand?

Answer 9

Lateral Border of the Anatomical Snuffbox

Question 10

Where does the Abductor Pollicis Longus Originate from?

Answer 10

1. Interosseous Membrane
2. Adjacent Posterior Surface of the Radius
3. Adjacent Posterior Surface of the Ulna

Question 11

Where does the Abductor Pollicis Longus attach distally?

Answer 11

Lateral Part of the Base of Metacarpal I

Question 12

What is the function of the Abductor Pollicis Longus?

Answer 12

Abduction of the Thumb

Question 13

What is the innervation of the Abductor Pollicis Longus?

Answer 13

Posterior Interosseous Branch of the Radial Nerve

Question 14

Is the Extensor Pollicis Brevis an Anatomically Superficial or Deep Muscle of the Posterior Forearm?

Answer 14

Deep

Question 15

Where is the Extensor Pollicis Brevis located, in relation to the Abductor Pollicis Longus?

Answer 15

1. Medially

2. Deep

Question 16

What does the Tendon of the Extensor Pollicis Brevis contribute to in the Hand?

Answer 16

Lateral Border of the Anatomical Snuffbox

Question 17

Where does the Extensor Pollicis Brevis Originate from?

Answer 17

1. Posterior Surface of the Radius

2. Interosseous Membrane

Question 18

Where does the Extensor Pollicis Brevis attach distally?

Answer 18

Base of the Proximal Phalanx of the Thumb

Question 19

What is the function of the Extensor Pollicis Brevis?

Answer 19

1. Extension of the Metacarpopharangeal Joint of the Thumb

2. Extension of the Carpometacarpal Joints of the Thumb

Question 20

What is the innervation of the Extensor Pollicis Brevis?

Answer 20

Posterior Interosseous Branch of the Radial Nerve

Question 21

Is the Extensor Pollicis Longus an Anatomically Superficial or Deep Muscle of the Posterior Forearm?

Answer 21

Deep

Question 22

Does the Extensor Pollicis Longus have a Larger or Smaller Belly than the Extensor Pollicis Brevis?

Answer 22

Larger

Question 23

Where does the Tendon of the Extensor Pollicis Longus travel in the Wrist?

Answer 23

Medially to the Dorsal Tubercle

Question 24

How does the Tendon of the Extensor Pollicis Longus use the Dorsal Tubercle?

Answer 24

The Dorsal Tubercle is used as a “Pulley” to increase the Force Exerted

Question 25

What does the Tendon of the Extensor Pollicis Longus contribute to in the Hand?

Answer 25

Medial Border of the Anatomical Snuffbox

Question 26

Where does the Extensor Pollicis Longus Originate from?

Answer 26

1. Posterior Surface of the Ulna

2. Interosseous Membrane

Question 27

Where does the Extensor Pollicis Longus attach distally?

Answer 27

Distal Phalanx of the Thumb

Question 28

What is the function of the Extensor Pollicis Longus?

Answer 28

Extension of all Joints of the Thumb:

1. Extension of the Carpometacarpal Joint
2. Extension of the Metacarpophalangeal Joint
3. Extension of the Interphalangeal Joint

Question 29

What is the innervation of the Extensor Pollicis Longus?

Answer 29

Posterior Interosseous Branch of the Radial Nerve