MSK 20 - Anatomy of the Hand + Wrist Flashcards
How do you remember the 12 muscles in the posterior forearm?
- The rule of 3’s
1) 3 wrist movers
2) 3 finger movers
3) 3 thumb movers
4) 3 others
What are the 3 wrist mover muscles in the posterior forearm?
What are their origins + insertions?
What are the actions they perform?
1) Extensor carpi radialis longus - lateral supracondylar ridge of humerus –> base of 2nd metacarpal. Extends + abducts wrist.
2) Extensor carpi radialis brevis - lateral epicondyle of humerus –> base of 3rd metacarpal. Extends + abducts wrist.
3) Extensor carpi ulnaris - Lateral epicondyle of humerus —> base of 5th metacarpal. Extends + adducts wrist.
What are the 3 finger mover muscles in the posterior forearm?
What are their origins + insertions
What are the actions they perform?
1) Extensor digitorum - lateral epicondyle of humerus –> extensor hood of 4 digits. Extends medial 4 digits
2) Extensor digiti minimi - lateral epicondyle of humerus —> extensor hood of little finger. Extends little finger.
3) Extensor indicis - Distal ulnar –> extensor hood of index finger. Extends index finger
What are the 3 thumb mover muscles in the posterior forearm?
What are their origins + insertions?
What are the actions they perform?
1) Extensor pollicis longus - mid ulna –> base of distal phalanx in thumb. Extends thumb
2) Extensor pollicis brevis - distal radius –> base of proximal phalanx of thumb. Extend thumb
3) Abductor pollicis longus - proximal ulna –> base of 1st metacarpal. Abducts thumb
What are the 3 other muscles in the posterior forearm?
What are their origins + insertions?
What are the actions they perform?
1) Brachioradialis - lateral supracondylar ridge of humerus –> distal radius. Weak elbow flexor.
2) Supinator. Lateral epicondyle of humerus to proximal radius. Supinates forearm
3) Anconeus - Lateral epicondyle of humerus –> proximal ulna. Weak extensor at elbow.
Think BSA.
What innervates all 12 muscles in the posterior forearm?
- Radial Nerve
Which 7 of the posterior forearm muscles are superficial?
Which 5 of the posterior forearm muscle are deep?
Superficial =
- 3 x wrist movers
- 2 x finger movers (excluding extensor indicis)
- 2 x others (excluding supinator)
Deep =
- Extensor indicis
- Supinator
- 3 x thumb movers
What type of joint is the wrist joint?
What are the movement of the wrist?
- Condyloid type synovial joint. Articulation between distal radius + proximal carpal bones (radio-carpal joint)
- Flexion, extension, radial deviation (abduction), ulnar deviation (adduction), circumduction
What are the 8 carpal bones (4 proximal and 4 distal)?
Use “so long to pinky, here comes the thumb”
Proximal - scaphoid, lunate, triquetral + pisiform (L to R)
Distal - hamate, capitate, trapezoid + trapezium (R to L)
Remember - trapezium is under the thumb
What is the most commonly fractured carpal bone that is at high risk of AVN due to retrograde blood supply?
Scaphoid
What is the carpal tunnel between?
What does it contain?
- Between carpal bones + flexor retinaculum
- Flexor tendons (x4) and median nerve
- Commons site of nerve compression
What are the borders of the anatomical snuffbox?
What does it contain?
- Radial border (lateral) - tendons of abductor pollicis longus and extensor pollicis brevis
- ulnar border (medial) - tendon of extensor pollicis longus
- floor (scaphoid + trapezium), roof (skin)
- Radial artery, radial nerve + cephalic vein
What are the 3 kinds of joints in the hand?
1) Carpometacarpal joints (CMCJ) - 1 to 5, in-between carpal bones and metacarpals.
2) Metacarpophalangeal joints (MCPJ) - in between metacarpals and phalanges
3) Interphalangeal joints (PIPJ or DIPJ) - 2 on digits, 1 on thumb. In between proximal/middle and middle/distal phalanxes.
What are the movements of the thumb?
- Flexion, extension, palmar abduction, radial abduction, opposition, retropulsion, abduction, adduction.
What are the 4 compartments that the muscles of the hand are split into?
1) Thenar muscles
2) Hypothenar muscles
3) Adductor compartment
4) Central compartment
