Posterior Forearm and Wrist

Question 1

Brachioradialis

Answer 1

Origin: supracondylar ridge
Insertion: distal radius
Inn: radial n
Action: weak flexor of forearm, strongest when forearm is in mid-pronate position

Question 2

Extensor Carpi Radialis Longus

Answer 2

Origin: supracondylar ridge
Insertion: 2nd metacarpal
Inn: radial n
Action: extends and abduct the hand, active during fist clenching

Question 3

Extensor Carpi Radialis Brevis

Answer 3

Origin: lateral epicondyle
Insertion: dorsal base of 3rd epicondyle
Inn: deep branch of radial n
Action: extend and abduct hand, active during fist clenching

Question 4

Extensor Digitorum

Answer 4

Origin: lateral epicondyle
Insertion: phalanx of digits 2-5
Inn: deep branch of radial n
Action: extends primarily at MCP and secondarily at IP joints of digits 2-5

Question 5

Extensor hoods and expansions

Answer 5

formed from the 4 tendons of extensor digitorum
1 median band- attaches at the base of middle phalanx
2 lateral bands- attaches at the base of distal phalanx

Question 6

Extensor Digiti Minimi

Answer 6

Origin: lateral epicondyle
Insertion: 5th digit
Inn: deep branch of radial n
Action: extends 5th digit primarily at MCP and secondarily at IP joints

Question 7

Extensor Carpi Ulnaris

Answer 7

Origin: lateral epicondyle and ulna
Insertion: 5th metacarpal
Inn: deep branch of radial n
Action: extends and adducts hand, active during fist clenching

Question 8

lateral epicondylitis

Answer 8

“tennis elbow”
most common overuse injury
Repeated forceful flexion and extension of wrist
strains common extensor tendon
produces inflammation of periosteum of lateral epicondyle
pain at lateral epicondyle that radiates down forearm
pain with opening door and lifting glass

Question 9

Supinator

Answer 9

Origin: lateral epicondyle and ulna
Insertion: radius
Inn: deep branch of radial n
Action: supinates forearm

Question 10

Abductor Pollicis Longus

Answer 10

Origin: ulna, radius, and interosseous membrane
Insertion: base of 1st metacarpal
Inn: posterior interosseous n
Action: abducts thumb

Question 11

Extensor Pollicis Brevis

Answer 11

Origin: posterior radius and interosseous membrane
Insertion: proximal phalanx of 1st digit
Inn: posterior interosseous n
Action: extends thumb

Question 12

Extensor Pollicis Longus

Answer 12

Origin: posterior ulna and interosseous membrane
Insertion: distal phalanx of 1st digit
Inn: posterior interosseous n
Action: extends thumb

Question 13

Extensor Indicis

Answer 13

Origin: ulna and interosseous membrane
Insertion: 2nd digit
Inn: posterior interosseous n
Action: extends digit 2

Question 14

Synovial Tendon Sheaths

Answer 14

Extensor retinaculum: holds extensor tendons in place at wrists, creates 6 extensor tunnels
Synovial tendon sheaths: cover the tendons to reduce friction
Intertendinous connections: restrict independent extension of fingers

Question 15

De Quervain Tenosynovitis

Answer 15

“texting thumb”
Often attributed to activities involving extension of thumb
Symptoms: pain or tenderness when moving thumb, turning wrist, grasping or making fist
swelling on radial side of dorsum of hand
tendon of extensor pollicis brevis and abductor pollicis longus

Question 16

Radial Nerve Path

Answer 16

leaves posterior compartment on anterior surface of lateral epicondyle
dives into deep and superficial branches around cubital fossa
deep branch: pierces supinator, provides its motor innervation and enters posterior compartment as posterior interosseous n