Topic 5: Muscles of the Forearm and Hand Flashcards
Where do muscles act?
At joints
What tells you the main action of a joint?
the position a muscle crosses at a joint
Anterior position of a joint and its movement & action
Movement - anteriorly directed
Action - flexion
Posterior position of a joint and its movement & action
Movement- posteriorly directed
Action - extension
Medial position of a joint and its movement & action
Movement - medially directed
Action - adduction
Lateral position of a joint and its movement & action
Movement - laterally directed
Action - abduction
What movements do horizontal horizontal/ oblique fibres produce?
Rotational movements
What movements do vertical muscular fibres produce?
Flexion, extension, adduction, abduction
Extrinsic hand muscles definiton
Connects outside of the hand but acts on the hand to move the hand
Counting method rules
- start laterally and count medially
- only count the muscles that cross the wrist joint
How many extrinsic muscles of the FLEXOR side of the hand according to the Counting Method?
SUPERFICIAL
3
How many extrinsic muscles of the FLEXOR side of the forearm according to the Counting Method?
MIDDLE
1
How many extrinsic muscles of the FLEXOR side of the hand according to the Counting Method?
DEEP
2
How many extrinsic muscles of the EXTENSOR side of the hand according to the Counting Method?
SUPERFICIAL
5
How many extrinsic muscles of the EXTENSOR side of the hand according to the Counting Method?
DEEP
4
What is the Common Extensor Origin (CEO)?
Lateral epicondyle of the humerus
What is the Common Flexor Origin (CFO)?
Medial epicondyle of the humerus
POSTERIOR FOREARM
Muscles of the superficial layer (lateral to medial)
- extensor carpi radialis longus
- extensor carpi radialis brevis
- extensor digitorum
- extensor digiti minimi
- extensor carpi ulnaris
POSTERIOR FOREARM
Deep layer (lateral to medial)
- abductor pollicis longus
- extensor pollicis brevis
- extensor pollicis longus
- extensor indicis
What muscles make up the anatomical snuffbox?
- extensor pollicis brevis
- abductor pollicis longus
- extensor pollicis longus
What muscles are left in the posterior forearm that arent counted with the counting method?
- brachioradialis
- anconeus
- supinator
ANTERIOR FOREARM
Superficial layer (lateral to medial)
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
ANTERIOR FOREARM
Middle layer (lateral to medial)
Flexor digitorum superficialis
ANTERIOR FOREARM
Deep layer (lateral to medial)
- flexor digitorum profundus
- flexor pollicis longus
What muscles are left in the anterior forearm excluded from the counting method?
- pronator teres
- pronator quadratus
Landmark method
What is it:
1. next to/ deep to/ superficial to?
2. what pierces it? e.g. radial nerve pierces supinator
Where do the carpi muscles attach to?
bases of metacarpals
Where do the digitorum muscles attach to?
- phalanges (flexor side)
- extensor expansion (extensor side)
Where do the pollicis muscles attach to?
the thumb
INTRINSIC HAND MUSCLES
Axis of the hand
3rd finger (middle finger)
How far can the thumb rotate medially?
through 90 degrees
INTRINSIC MUSCLES OF THE HAND
Counting method for intrinsics
3 + 3 + 3
Thenar muscles (lateral to medial)
- abductor pollicis brevis
- flexor pollicis brevis
- opponens pollicis
Hypothenar muscles (lateral to medial)
- abductor digiti minimi
- flexor pollicis brevis
- opponens digiti minimi
Middle muscles (lateral to medial)
- adductor pollicis
- lumbricals
- interossei – palmar and dorsal
Pneumonic for intrinsic muscles of the hand
The Three Musketeers!
- All
- For
- One
—-> and
- One
- For
- All
What joints do the abductor muscles act at?
MCP and CMC jts
(outermost of the 3 muscles)
What joints do the flexor muscles act at?
MCP and CMC jts
(innermost of the 3 muscles)
What joints do the opponens muscles work at?
CMC jts
- rotation of the metacarpal
(deepest of 3 muscles)
What are the two heads of the ADDuctor pollicis?
Oblique & transverse heads