Forearm Extensors

Question 1

O of Brachioradialis

Answer 1

Proximal 2/3 of lateral supracondylar ridge of humerus

Question 2

I of Brachioradialis

Answer 2

Lateral surface of distal end of radius proximal to styloid process

Question 3

Innervation of Brachioradialis

Answer 3

Radial n. (C5,C6,C7)

Question 4

O of Extensor Carpi Radialis Longus

Answer 4

Lateral supracondylar ridge of humerus

Question 5

I of Extensor Carpi Radialis Longus

Answer 5

Base of 2nd Metacarpal

Question 6

O of Extensor Carpi Radialis Brevis

Answer 6

Lateral epicondyle of the humerus

Question 7

I of Extensor Carpi Radialis Brevis

Answer 7

Base of 3rd metacarpal

Question 8

Innervation of Extensor Carpi Radialis Longus

Answer 8

Radial Nerve (C6,C7)

Question 9

Innervation of Extensor Carpi Radialis Brevis

Answer 9

Deep Branch of Radial Nerve (C7,C8)

Question 10

What is the difference between innervations of Extensor Carpi Radialis Longus vs. Brevis?

Answer 10

Longus is Radial Nerve (C6,C7)

Brevis is Deep branch of Radial Nerve (C7,C8)

Question 11

O & I of Extensor Digitorum

Answer 11

O is Lateral Epicondyle of Humerus

I is Extensor expansions of medial 4 digits

Question 12

Innervation of Extensor Digitorum

Answer 12

Posterior Interosseus Nerve (C7,C8)

Question 13

Posterior Interosseus Nerve is a branch of what nerve

Answer 13

Radial nerve

Question 14

Action of Extensor Digitorum

Answer 14

Extends medial 4 digits at MCP, PIP, & DIP

Question 15

O & I of Extensor Digiti Minimi

Answer 15

O is Lateral Epicondyle of the Humerus

I is Extensor Expansions of 5 digit

Question 16

Innervation of Extensor Digit Minimi is the same as what other extensor muscle?

Answer 16

Extensor Digitorum

Question 17

Innervation of Extensor Digiti Minimi

Answer 17

Posterior Interosseus Nerve (C7,C8)

Question 18

O if Extensor Carpi Ulnaris

Answer 18

1. ) Lateral Epicondyle of Humerus

2. ) Posterior border of Ulna

Question 19

Innervation of Extensor Carpi Ulnaris

Answer 19

Posterior Interosseus Nerve (C7,C8)

Question 20

Which 7 muscles of the forearm are innervated by Posterior Interosseus Nerve (C7,C8) ?

Answer 20

1. ) Extensor Digitorum
2. ) Extensor Digiti Minimi
3. ) Extensor Carpi Ulnaris
4. ) Extensor Pollicis Longus
5. ) Extensor Pollicis Brevis
6. ) Abductor Pollicis Longus
7. ) Extensor Indicis

Question 21

O of Anconeus

Answer 21

Lateral Epicondyle of Humerus

Question 22

I of Anconeus

Answer 22

1. ) Lateral surface of olecranon

2. ) Superior part of posterior surface of ulna

Question 23

Action of Anconeus

Answer 23

1. ) Assists triceps in extending elbow jt
2. ) Stabilizes elbow jt.;
3. ) Abducts ulna during pronation

Question 24

Innervation of Anconeus

Answer 24

Radial Nerve (C7,C8,T1)

Question 25

O of Supinator

Answer 25

1. ) Lateral epicondyle of humerus
2. ) Radial collateral & Annular ligaments
3. ) Supinator fossa & Crest of ulna

Question 26

I of Supinator

Answer 26

Lateral & posterior surfaces of proximal 1/3 of radius

Question 27

Innervation of Supinator

Answer 27

Deep branch of Radial Nerve (C7,C8)

Question 28

O of Abductor pollicis longus

Answer 28

1. ) Posterior surfaces of ulna & radius

2. ) Interosseus Membrane

Question 29

I of Abductor pollicis longus

Answer 29

Base of 1st metacarpal bone

Question 30

Along with abduction of the thumb what else does Abductor pollicis longus do?

Answer 30

Extends thumb at CMC joint

Question 31

O of Extensor Pollicis Brevis

Answer 31

1. ) Posterior surface of radius

2. ) Interosseus Membrane

Question 32

I of Extensor Pollicis Brevis

Answer 32

Base of proximal phalanx of thumb via extensor expansion

Question 33

Innervation of Extensor Pollicis Brevis

Answer 33

Posterior Interosseus Nerve (C7,C8)

Question 34

O of Extensor Pollicis Longus

Answer 34

1. ) Posterior surface & middle of ulna

2. ) Interosseus Membrane

Question 35

Key differences between Extensor Pollicis Brevis & Longus

Answer 35

1. ) Origin (Brevis is posterior surface of radius, Longus is posterior surface & middle of ulna)
2. ) Actions (Brevis extends Proximal Phalanx, Longus extends Distal Phalanx)

Question 36

O of Extensor Indicis

Answer 36

1. ) Posterior surface of Ulna

2. ) Interosseus Membrane

Question 37

I of Extensor Indicis

Answer 37

Extensor expansion of 2nd digit

Question 38

Innervation of Extensor Indicis

Answer 38

Posterior Interosseus Nerve (C7,C8)

Question 39

What is the only muscle of the “deep layer” of extensors is innervated by Deep Branch of Radial Nerve C7, C8?

Answer 39

Supinator

Question 40

What is the innervation of ALL deep layer extensors EXCEPT the supinator?

Answer 40

Posterior Interosseus Nerve (C7,C8)