Muscles Week 12

Question 1

What is the origin of the Extensor Pollicis Longus?

Answer 1

Posterior middle 1/3 of ulna and interosseous membrane

Question 2

Where does the Extensor Pollicis Longus insert?

Answer 2

Distal phalanx of thumb

Question 3

What is the action of the Extensor Pollicis Longus?

Answer 3

Extension of thumb (CMC, MCP, IP joints); assists in extension and radial flexion of wrist

Question 4

What is the innervation of the Extensor Pollicis Longus?

Answer 4

Radial nerve

Question 5

What is the origin of the supinator?

Answer 5

Lateral epicondyle of humerus and supinator crest of lateral ulna (near radial notch)

Question 6

Where does the supinator insert?

Answer 6

Proximal 1/3 of radial shaft

Question 7

What is the action of the supinator?

Answer 7

Supination of forearm

Question 8

What is the innervation of the supinator?

Answer 8

Radial nerve

Question 9

Where is the supinator located in relation to other muscles?

Answer 9

Deep to the forearm extensors and superficial to the head of the radius

Question 10

What is the origin of the Abductor Pollicis Longus?

Answer 10

Posterior surfaces of ulna, radius, and interosseous membrane (middle 1/3 of forearm)

Question 11

Where does the Abductor Pollicis Longus insert?

Answer 11

Base of 1st metacarpal (lateral side)

Question 12

What is the primary action of the Abductor Pollicis Longus?

Answer 12

Abduction of thumb (CMC joint)

Also: radial deviation of wrist, assists with extension and rotation of thumb, and flexion/supination of hand at wrist.

Question 13

Which nerve innervates the Abductor Pollicis Longus?

Answer 13

Radial nerve

Question 14

What is the origin of the Extensor Pollicis Brevis?

Answer 14

Posterior distal 1/3 surface of radius & interosseous membrane

Question 15

Where does the Extensor Pollicis Brevis insert?

Answer 15

Base of proximal phalanx of thumb

Question 16

What is the action of the Extensor Pollicis Brevis?

Answer 16

Extension of proximal phalanx & 1 metacarpal of thumb (mild radial flexion of wrist)

Question 17

Which nerve innervates the Extensor Pollicis Brevis?

Answer 17

Radial nerve

Question 18

What is the origin of the Extensor Pollicis Longus?

Answer 18

Posterior middle 1/3 of ulna and interosseous membrane

Question 19

Where does the Extensor Pollicis Longus insert?

Answer 19

Distal phalanx of thumb

Question 20

What is the action of the Extensor Pollicis Longus?

Answer 20

Extension of thumb (CMC, MCP, IP joints); assists in extension and radial flexion of wrist

Question 21

What is the innervation of the Extensor Pollicis Longus?

Answer 21

Radial nerve

Question 22

What is the origin of the Extensor Indicis?

Answer 22

Posterior distal 1/3 of ulna and interosseous membrane

Question 23

Where does the Extensor Indicis insert?

Answer 23

Base of middle and distal phalanx of index finger (via extensor expansion & extensor digitorum muscle tendon)

Question 24

What is the action of the Extensor Indicis?

Answer 24

Extension of index finger (MCP, PIP, DIP)

Weak extension of hand and adduction of index finger

Question 25

What is the innervation of the Extensor Indicis?

Answer 25

Radial nerve

Question 26

What is the origin of the Flexor Pollicis Longus?

Answer 26

Radius (middle 1/3 anterior surface) and interosseous membrane

Question 27

What is the insertion point of the Flexor Pollicis Longus?

Answer 27

Base of distal phalanx of thumb (anterior aspect)

Question 28

What is the primary action of the Flexor Pollicis Longus?

Answer 28

Flexion of thumb (CMC, MCP, IP joints)

Also crosses wrist joint for weak wrist flexion.

Question 29

Which nerve innervates the Flexor Pollicis Longus?

Answer 29

Median nerve