Forearm muscles Origins, Insertions, Actions

Question 1

Pronator teres

Answer 1

O: Humeral head - medial supracondylar ridge
Ulnar head - coronoid process
I: Lateral surface of radius distal to supinator insertion
A: Pronates forearm; assist forearm flexion

Question 2

Flexor carpi radialis

Answer 2

O: Medial epicondyle of humerus
I: Base of 2nd and 3rd metacarpals
A: Flex wrist, radial deviation of hand, assist pronation & elbow flexion

Question 3

Palmaris longus

Answer 3

O: Medial epicondyle of humerus
I: Palmar aponeurosis
A: Flex wrist, tighten palmar aponeurosis, assists elbow flexion

Question 4

Flexor carpi ulnaris

Answer 4

O: Humeral head - medial epicondyle
Ulnar head - olecranon
I: Pisiform, hook of hamate, base of 5th metacarpal
A: Flex wrist, ulnar deviation of hand, assist elbow flexion

Question 5

Flexor digitorum superficialis

Answer 5

O: Humero-ulnar head - medial epicondyle
Radial head - anterior upper 1/2 of radius
I: Splits to attach to lateral aspects of base of the middle phalanx of digits 2-5
A: Flex middle phalanges at PIP joint; assist MCP flexion & flexion at wrist, weak elbow flexor

Question 6

Flexor digitorum profundus

Answer 6

O: Proximal 2/3 of anteromedial shaft of ulna & interosseus membrane
I: Base of the distal phalanx of digits 2-5
A: Flex DIP of fingers 2-5, secondary flexor at PIP & MCP joints; assists flexion at the wrist

Question 7

Flexor pollicis longus

Answer 7

O: Middle anterior surface of radius & adjacent interosseus membrane
I: Base of distal phalanx of thumb (palmar)
A: Flex thumb at CMC, MCP, and IP joint

Question 8

Pronator quadratus

Answer 8

O: Distal 1/4 of the anterior surface of the ulna
I: Distal 1/4 of the anterior surface of the radius
A: Pronate forearm, distal radioulnar stabilization

Question 9

Brachioradialis

Answer 9

O: Lateral supracondylar ridge, intermuscular septum
I: Lateral side of distal radius (styloid process)
A: Flex elbow; assist pronation & supination (return to neutral)

Question 10

Extensor carpi radialis longus

Answer 10

O: Lateral supracondylar ridge, lateral intermuscular septum
I: Dorsum of base of 2nd metacarpal
A: Extend wrist, radially deviate hand

Question 11

Extensor carpi radialis brevis

Answer 11

O: Lateral epicondyle of humerus
I: Dorsum of base of 3rd metacarpal
A: Extend wrist; assist radial deviation of hand

Question 12

Extensor digitorum

Answer 12

O: Lateral epicondyle of humerus (via common extensor tendon)
I: Extensor expansion of digits 2-5 (to proximal, middle, distant phalanges)
A: Extend at MCP & IP joints; assist extension at wrist

Question 13

Extensor digiti minimi

Answer 13

O: Lateral epicondyle of humerus
I: Extensor expansion of pinky finger
A: Extension at MCP & IP joints of pinky finger; weak wrist extension, ulnar deviation and abduction of 5th digit

Question 14

Extensor carpi ulnaris

Answer 14

O: Lateral epicondyle of humerus & midshaft of posterior ulna
I: Dorsum of base of 5th metacarpal
A: Extend & ulnarly deviate hand (at wrist)

Question 15

Supinator

Answer 15

O: Lateral epicondyle of humerus, lateral collateral and annular ligaments, supinator crest of ulna (on olecranon)
I: Lateral and anterior surface of proximal 1/3 of radius
A: Supinate forearm

Question 16

Abductor pollicis longus

Answer 16

O: Posterior surfaces of middle 1/3 of radius, ulna, and interosseus membrane
I: Radial side of base of 1st metacarpal
A: Abduct thumb; radially deviate & flex at wrist

Question 17

Extensor pollicis brevis

Answer 17

O: Posterior surface of the distal radius, interosseus membrane
I: Dorsum of base of proximal phalanx of thumb
A: Extend proximal phalanx of thumb, assist extension at CMC joint, radial deviation at wrist

Question 18

Extensor pollicis longus

Answer 18

O: Middle 1/3 of posterior shaft of ulna & interosseus membrane
I: Dorsum of base of distal phalanx of thumb
A: Extend IP & MCP joints of thumb; assist radial deviation of wrist; CMC adduction; weak wrist flexion

Question 19

Extensor indicis

Answer 19

O: Distal shaft of ulna and interosseus membrane
I: Index finger - with tendon sheath for extensor digitorum, extensor hood
A: Extends all joints of index finger; assist adduction; weak wrist extension