Thumb Muscles

Question 1

What is the origin of the Flexor Pollicis Longus?

Answer 1

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

This muscle is responsible for flexing the thumb.

Question 2

What is the insertion point of the Supinator?

Answer 2

Proximal 1/3 of radial shaft

This muscle is involved in the supination of the forearm.

Question 3

What action does the Abductor Pollicis Longus perform?

Answer 3

Abduction of thumb (CMC joint)

It also assists with radial deviation of the wrist.

Question 4

Which nerve innervates the Extensor Pollicis Longus?

Answer 4

Radial nerve

This muscle extends the thumb at the CMC, MCP, and IP joints.

Question 5

What are the movements of the thumb?

Answer 5

• Flexion
• Extension
• Abduction
• Adduction
• Opposition

These movements are essential for thumb functionality.

Question 6

What is the main action of the Flexor Pollicis Longus?

Answer 6

Flexion of the thumb (CMC, MCP, IP joints)

It also contributes to weak wrist flexion.

Question 7

Fill in the blank: The _______ is deep to the forearm extensors and superficial to the head of the radius.

Answer 7

Supinator

Question 8

What is the clinical test for DeQuervain’s syndrome?

Answer 8

Finkelstein’s Test

This syndrome is characterized by tenosynovitis of the thumb tendons.

Question 9

What is the origin of the Extensor Pollicis Brevis?

Answer 9

Posterior distal 1/3 surface of radius & interosseous membrane

This muscle extends the proximal phalanx and 1st metacarpal of the thumb.

Question 10

True or False: The Extensor Indicis assists in the extension of the index finger.

Answer 10

True

It also weakly extends the hand and adducts the index finger.

Question 11

What are the short muscles of the thumb?

Answer 11

• Abductor pollicis brevis
• Flexor pollicis brevis
• Opponens pollicis
• Adductor pollicis

These muscles are located within the thenar eminence.

Question 12

What is the action of the Supinator muscle?

Answer 12

Supination of forearm

This muscle is crucial for rotating the forearm.

Question 13

What is the origin of the Abductor Pollicis Longus?

Answer 13

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

This muscle also assists with extension and rotation of the thumb.

Question 14

What structure goes around the radial head?

Answer 14

Annular ligament

This ligament is important for the stability of the elbow joint.

Question 15

What is the action of the Extensor Digitorium?

Answer 15

Extension of the fingers

This muscle extends the digits at the MCP, PIP, and DIP joints.

Question 16

Fill in the blank: The _______ is responsible for weak wrist flexion due to its crossing of the wrist joint.

Answer 16

Flexor Pollicis Longus

Question 17

What is the insertion point of the Extensor Pollicis Longus?

Answer 17

Distal phalanx of thumb

This muscle assists in the extension of the thumb’s joints.