Biomechanics Presentation

extensor carpi ulnarisOrigin: Lateral epicondyle of humerus and

posterior border of ulnaInsertion: Base of 5th metacarpalAction: Extends and adducts hand at wrist

joint

extensor carpi radialis brevis Origin:  Lateral epicondyle of humerusInsertion:  Base of 3rd metacarpalAction: acts to extend and abduct the wrist

Flexor digitorum superficialis Origin: Humeroulnar head: medial

epicondyle of humerus, ulnar collateral ligament, and coronoid process of ulna; Radial head: superior half of anterior border of radius

Insertion:  Bodies of middle phalanges of digits 2 – 5

Action: extrinsic flexor muscle of the fingers at the proximal interphalangeal joints

flexor digitorum profundus  Origin: Proximal 3/4 of medial and anterior

surfaces of ulna and interosseous membraneInsertion:  Base of the distal phalanx of digits

2 – 5Action: flexor digitorum profundus helps flex

the fingers. The muscle originates in the upper part of the ulna bone and stretches to insertion at the distal phalanges in the tips of the fingers.

Flexor pollicis longusOrigin: Anterior surface of radius and

adjacent interosseous membraneInsertion: Base of distal phalanx of thumbAction: Flexes phalanges of 1st digit (thumb)

extensor digitorumOrigin: Lateral epicondyle of humerusInsertion: Extensor expansions of medial four

digitsAction: Extends medial four digits at

metacarpophalangeal joints; Extends hand at wrist joint

extensor indicisOrigin: Posterior surface of ulna and

interosseous membraneInsertion: Extensor expansion of 2nd digitAction: Extends 2nd digit and helps to extend

hand

extensor digiti minimiOrigin: Lateral epicondyle of humerusInsertion: Extensor expansion of 5th digitAction: Extends 5th digit at

metacarpophalangeal and interphalangeal joints

Extensor pollicis longusOrigin: Posterior surface of middle 1/3 of ulna

and interosseous membraneInsertion: Base of distal phalanx of thumbAction: Extends distal phalanx of thumb at

carpometacarpal and interphalangeal joints

extensor pollicis brevisOrigin: Posterior surfaces of radius and

interosseous membraneInsertion: Base of proximal phalanx of thumb

Action: Extends proximal phalanx of thumb at carpometacarpal joint

abductor pollicis longusOrigin: Posterior surfaces of ulna, radius and

interosseous membraneInsertion: Base of 1st metacarpalAction: Abducts thumb and extends it at

carpometacarpal joint