Muscles of the forearm Flashcards
What are the two joints of the forearm and what are their functions?
Synovial hinge joint (elbow) –> flexion/extension
Synovial pivot joint (proximal radioulnar) –> supination / pronation.
What are the ligaments around the elbow joint and what are their functions?
Radial collateral ligament, ulnar collateral ligament,
annular ligament
Stabilise / strengthen joint
What are the muscles of the anterior compartment of the forearm?
Mainly flexors
Superficial -> 3 flexors of wrist (carpi), 1 pronator
Intermediate -> 1 flexor of digits 2-5 (digitorum)
Deep -> 1 flexor of digits 2-5 (digitorum), 1 flexor of thumb (pollicis), 1 pronator.
(Superficial + intermediate from common flexor origin)
What are the muscles of the superficial layer of the anterior compartment?
Pronator teres: insertion -> radius
Flexor carpi radialis: insertion -> base of 2nd + 3rd metacarpal.
Palmaris longus: insertion -> palmar aponeurosis
Flexor carpi ulnaris: origin -> medial epicondyle, insertion -> pisiform, hook of hamate, base of 5th metacarpal.
What is the clinical significance of the superficial layer of muscles?
Golfers elbow / medial epicondylitis -> inflammation of tendons at CFO due to overuse/excessive gripping
What is the muscle of the intermediate layer and what is its origin, insertion and action?
Flexor digitorum superficialis
Origin: common flexor origin
Insertion: base of middle phalanx of digits 2,3,4,5
Action: flexes wrist, metacarpal phalangeal joint (knuckles) + proximal interphalangeal joint.
What is the origin, insertion and action of the flexor digitorum profundus and which layer is it found in?
Deep
Origin: ulna + interosseous membrane
Insertion: distal phalynx of digits 2, 3, 4, 5
Action: flexes wrist, metacarpophalangeal joints at digit 2,3,4, 5 + proximal and distal interphalangeal joints.
What is the origin, insertion and action of the flexor pollicis longus and which layer is it found in?
Deep
Origin: radius + interosseous membrane
Insertion: distal phalynx of thumb.
Action: flexes thumb.
What is the remaining muscle of the deep layer?
Pronator quadratus
What are the muscles of the posterior compartment of the forearm?
Mainly extensors
Superficial muscles -> 3 extensors of wrist (carpi), 1 extensor of digits 2-5 (digitorum), 1 accessory extensor to digit 5 (digiti minimi), brachioradialis + anconeus.
Deep muscles -> 2 extensors of thumb (pollicis), 1 abductor of thumb (pollicis), 1 accessory extensor to digit 2 (indicis), 1 supinator.
What are the muscles of the superficial layer and what is their origin?
Extensor carpi radialis longus/brevis Extensor digitorum Extensor digiti minimi (accessory to extensor digitorum) Extensor carpi ulnaris Common extensor origin
What is the clinical significance of the superficial layer?
Tennis elbow / lateral epicondylitis -> inflammation of tendons at CEO due to overuse/forceful extension
What is the origin, insertion and action of the extensor carpi radialis longus and brevis?
Longus Origin: supracondylar ridge Insertion: base of 2nd metacarpal Brevis Origin: common extensor origin Insertion: base of 3rd metacarpal. Action: extends wrist
What is the origin, insertion and action of the extensor digitorum?
Origin: common extensor origin.
Insertion of the 4 tendons: middle phalynx of digits 2,3,4, 5 + distal phalynx of digit 2,3.4, 5.
Action: extends wrist, metacarpophalangeal joint 2 to 5 + proximal and distal interphalangeal joint digits 2 to 5.
What is the origin, insertion and action of the extensor carpi ulnaris?
Origin: common extensor origin
Insertion: base of 5th metacarpal
Action: extends wrist
What are the two other superficial muscles of the posterior compartment?
Brachioradialis Action: flexor when half pronated Anconeus Origin: lateral epicondyle Insertion: olecranon of ulna Action: stabilises elbow
What are the muscles of the deep layer of the posterior compartment?
Supinator Extensor indicis (accessory to extensor digitorum) Anatomical snuff box: Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus
Which muscles perform wrist abduction and adduction?
Abduction (radial deviation) -> flexor carpi radialis,
extensor carpi radialis (longus + brevis).
Adduction (ulnar deviation) -> flexor carpi ulnaris, extensor carpi ulnaris.
Splints wrist to allow fine movements of hand
Which muscles are involved in supination?
Biceps brachii
Supinator:
Origin: superficial head from lateral epicondyle + deep head from ulna.
Insertion: proximal shaft of radius.
Which muscles are involved in pronation?
Pronator teres has humeral + ulnar heads Insertion: radius Pronator quadratus Origin: ulna Insertion: radius
What is the position of the radius and ulna during pronation and supination?
During pronation -> radius rotates over ulna
During supination -> radius + ulna are parallel
What is the purpose of the flexor retinaculum?
Transverse carpal ligament
Prevents bowing of tendons, separates tendons into compartments.
What is the carpal tunnel and what are its contents?
Tunnel for flexor tendons to digits + median nerve. Median nerve Flexor policis longus Flexor digitorum superficialis Flexor digitorum profundus Synovial sheaths
What are the insertions to the long tendons?
Tendons to digits 2 – 5
Extensor digitorum into middle + distal phalanx
Flexor digitorum superficialis into middle phalanx
Flexor digitorum profundus into distal phalanx
