4.1.2. Extensor Muscles of the Medial 4 Digits

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 the Medial 4 Digits?

Answer 6

1. Extensor Digitorum
2. Extensor Indicis Proprius
3. Extensor Digiti Minimi

Question 7

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

Answer 7

Superficial

Question 8

Where does the Extensor Digitorum Originate from?

Answer 8

Lateral Epicondyle of the Humerus

Question 9

What happens to the Extensor Digitorum, as it travels into the Distal Forearm?

Answer 9

It’s Flesh Belly Ends in a Tendon which passes under the Extensor Reinaculum, and then Divides into 4

Question 10

Where does the Extensor Digitorum attach distally?

Answer 10

Extensor Hood of Medial 4 Digits (the Fingers)

Question 11

What is the function of the Extensor Digitorum?

Answer 11

It is the Main Extensor of the Fingers:
1. Extension of the Medial 4 Digits at the Metacarpophalangeal Joint
2. Extension of the Medial 4 Digits at the Interphalangeal Joint

Question 12

What is the innervation of the Extensor Digitorum?

Answer 12

Deep Branches of the Radial Nerve

Question 13

How is the Extensor Digitorum function tested?

Answer 13

The Forearm is Pronated and the Fingers are Extended against Resistance

Question 14

Is the Extensor Indicis Proprius an Anatomically Superficial or Deep Muscle of the Posterior Forearm?

Answer 14

Deep

Question 15

Where does the Extensor Indicis Proprius Originate from?

Answer 15

1. Posterior Surface of the Ulna
2. Interosseous Membrane, Distal to the Extensor Pollicus Longus

Question 16

Where does the Extensor Indicis Proprius attach distally?

Answer 16

Extensor Hood of the Index Finger

Question 17

What is the function of the Extensor Indicis Proprius?

Answer 17

1. It allows for the Index Finger to be Independent of the other Digits during Extension
2. Extension of the Index Finger

Question 18

What is the innervation of the Extensor Indicis Proprius?

Answer 18

Posterior Interosseous Branch of the Radial Nerve

Question 19

Is the Extensor Digiti Minimi an Anatomically Superficial or Deep Muscle of the Posterior Forearm?

Answer 19

Superficial

Question 20

1. Where does the Extensor Digiti Minimi Originate from?
2. Where is the Extensor Digiti Minimi thought to have Originated from?

Answer 20

1. Lateral Epicondyle of the Humerus
2. It is thought that this Originates from the Extensor Digitorum Muscle, and in some people these 2 Muscles are Fused Together

Question 21

Where does the Extensor Digiti Minimi attach distally?

Answer 21

Extensor Hood of the Little Finger

Question 22

What attaches to the Extensor Hood of the Little Finger, other than the Extensor Digiti Minimi?

Answer 22

Extensor Digitorum Tendon

Question 23

What is the function of the Extensor Digiti Minimi?

Answer 23

1. Extension of the Little Finger
2. Contributes to the Extension of the Wrist

Question 24

What is the innervation of the Extensor Digiti Minimi?

Answer 24

Deep Branch of the Radial Nerve

Question 25

Where is the Extensor Digiti Minimi located anatomically, in relation to the Extensor Digitorum?

Answer 25

Medially