Extensors of Forearm & Wrist Flashcards
What 3 muscles extend the wrist?
1) Extensor carpi radialis longus
2) Extensor carpi radialis brevis
3) Extensor carpi ulnaris
What 3 muscles extend the digits (except thumb)?
1) Extensor digitorum
2) Extensor indicis
3) Extensor digiti minimi
What 3 muscles extend the thumb?
1) Abductor pollicus longus
2) Extensor pollicus longus
3) Extensor pollicus brevis
What is the most commonly fractured carpal bone?
Scaphoid
What extends the IP joints (DIP + PIP)?
Extensor tendon
What muscles extend the MCP joints?
Extensor digitorum
What muscle is part of the extensor/supinator compartment but actually functions as an elbow flexor?
Brachioradialis
What is the common attachment site for the superficial forearm extensor muscles?
Lateral epicondyle
What are the 6 superficial extensor muscles?
1) Brachioradialis
2) Extensor carpi radialis longus
3) Extensor carpi radialis brevis
4) Extensor carpi ulnaris
5) Extensor digitorum
6) Extensor digiti minimi
What are the 5 deep extensor muscles?
1) Supinator
2) Abductor pollicis longus
3) Extensor pollicis brevis
4) Extensor pollicis longus
5) Extensor indicis
Brachioradialis (origin + insertion)
Origin:
- Lateral supracondylar ridge of humerus
Insertion:
- Lateral surface of distal end of radius
Brachioradialis (function + innervation)
Function:
1) Flex FA
2) Pronate/supinate
Innervation: Radial nerve (C6) (C5, C7)
Supinator (origin + insertion)
Origin:
-Lateral epicondyle of humerus, radial collateral and annular ligaments, supinator fossa, crest of ulna
Insertion:
- Lateral, posterior and anterior surfaces of radius
Supinator (function + innervation)
Function:
- Supinate FA
Innervation: Radial nerve (C6) (C5)
What nerve is the continuation of the deep branch of the radial nerve?
Posterior interosseous nerve (PIN)
Posterior interosseous nerve (PIN)
Continuation of deep branch of radial nerve
- Runs in between superficial + deep parts of supinator
What fascia holds all the extensor tendons?
Extensor retinaculum
Name all extensor tendon compartments (+ contents)
1) Extensor pollicus brevis + abductor pollicus longus
2) Extensor carpi radialis longus + extensor carpi radialis brevis
3) Extensor pollicus longus
4) Extensor digitorum + extensor indicis
5) Extensor digiti minimi
6) Extensor carpi ulnaris
What are the contents of the anatomical snuffbox?
1) Radial artery (superficial)
2) Scaphoid bone (deep)
3) Superficial radial nerve (“roof”)
What are the boundaries of the anatomical snuffbox?
Extensor pollicus longus (medial)
Extensor pollicus brevis (lateral)
*Abductor pollicus longus lies more lateral to EPB
What nerve innervates the palmar + dorsal interossous muscles?
Ulnar nerve
What muscles attach to the dorsal “hood”?
1) Extensor digitorum
2) Lumbricals
3) Palmar interosseous
4) Dorsal interosseous
What nerve innervates all the extensor muscles?
Radial nerve
What bony structure does extensor pollicis longus loop around to angle towards the thumb?
Lister’s tubercle (dorsal tubercle) of radius
Where do the lumbricals originate from?
Tendons of flexor digitorum profundus
Brachioradialis (origin + insertion)
Origin:
-Lateral supracondylar ridge of humerus
Insertion:
-Lateral surface of distal end of radius
Brachioradialis (function + innervation)
Function:
- Flex forearm
- Pronate/supinate
Innervation:
- Radial nerve (C6) (C5,C7)
Supinator (origin + insertion)
Origin:
- Lateral epicondyle of humerus
- Radial collateral and annular ligaments
- Supinator fossa
- Crest of ulna
Insertion:
- Lateral, posterior and anterior surfaces of radius
Supinator (function + innervation)
Function:
- Supinate forearm
Innervation:
- Radial nerve (C6) (C5)
Which nerve runs in between the superficial + deep parts of the supinator muscle?
Radial nerve
What branches does the radial nerve give off around the region of the lateral epicondyle?
1) Superficial branch of radial nerve
2) Posterior interosseous nerve (PIN)
* Also known as deep branch of radial nerve
Which muscle extends the MCP joints?
Extensor digitorum
Which muscles extend the DIP + PIP joints?
Extensor tendon facilitated mainly by lumbrical muscles
What symptom typically presents due to extensor tendon injury?
Mallet finger
Mallet finger
- Due to rupture/avulsion of extensor tendon
- Finger presents in flexed state
- Unable to extend finger
What separates the ulna bone from the carpal bones?
Triangular fibrocartilage complexx (TFCC)
What are the carpal bones bordered by laterally + medially?
Radial + ulnar collateral ligaments
What kind of a joint if the CMC joint of the thumb?
Saddle joint
What muscles flex the hand at the wrist?
1) Flexor carpi radialist
2) Flexor carpi ulnaris
3) Palmaris longus
Which muscles flex the digits?
1) Flexor digitorum superficialis
2) Flexor digitorum profundus
3) Flexor pollicis longus
What muscles extend the hand at the wrist?
1) Flexor carpi radialis longus
2) Flexor carpi radialis brevis
3) Flexor carpi ulnaris
Which muscles extend the digits (except the thumb)?
1) Extensor digitorum
2) Extensor indicis
3) Extensor digiti minimi
Which muscles extend the thumb?
1) Abductor pollicis longus
2) Extensor pollicis brevis
3) Extensor pollicis longus
Which muscles rotate the radius on the ulna?
1) Pronator teres
2) Pronator quadratus
3) Supinator
Which muscle is actually a stronger supinator than the supinator muscle?
Biceps brachii
