Extrinsic Muscles Flashcards
Superficial anterior compartment of forearm
> Pronator Teres > Flexor Carpi Radialis > Palmaris Longus > Flexor Carpi Ulnaris > Flexor Digitorum superficialis
Deep anterior compartment of forearm
> Flexor Digitorum Profundus
Flexor Pollucis Longus
Pronator Quadratus
Superficial posterior compartment of forearm
> Brachioradialis > Extensor Carpi Radialis Longus > Extensor Carpi Radialis Brevis > Extensor Carpi Ulnaris > Extensor Digitorum > Extensor Digiti Minimi
Deep Posterior compartment of forearm
> Extensor Indicis
Extensor Pollicis Longus
Extensor Pollicis Brevis
Abductor Pollicis Longus
Flexor Carpi Radialis (FCR)
- Position: laterally in superficial anterior compartment
- Origin: Medial epicondyle of humerus = common flexor tendon
- Insertion: Palmar base of of metacarpals 2-3
- Action: Wrist flexoin
: Wrist abduction
Innervation: Median nerve C6-7
Palmaris Longus (not present in everyone)
Origin: common flexor tendon (medial epicondyle)
Insertion: flexor retinaculum
: apex of palmar aponeurosis
Action: assists wrist flexion
: tightens palmar fascia
Innervation: Median nerve C7-8
Flexor Carpi Ulnaris (FCU)
Position: most medial of superficial anterior compartment
Origin: Common flexor tendon (medial epicondyle)
: medial olecranon + post border of ulna
Insertion: Pisiform (sesamoid bone)
: hook of hamate (pisohamate extension)
: base of 5th metacarpal (pisometacarpal extension)
Action: Flexion of wrist
: Adduction of wrist
: Synergic action in abduction of little finger
Innervation: Ulnar nerve C7-8
Flexor Digitorum Superficialis (FDS)
- Origin: Common flexor tendon (medial epicondyle)
: Coronoid process of ulna
: Proximal 2/3 of anterior radius - Insertion: 4 tendons to either side of palmar surface of middle phalanges 2-5
- Action: Wrist flexion
: MCP flexion in digits 2-5
: PIP flexion in digits 2-5
(key in grip strength + power) - Innervation: Median nerve C6-T1
Flexor Digitorum Profundus (FDP)
- Position: medial side of deep anterior compartment
- Origin: Medial side of coronoid process
: Ant + med surfaces of ulna (+adjacent IM) - Insertion: 4 tendons to palmar surface of distal phalanges 2-5
- Action: Wrist flexion
: MCP/PIP/DIP flexion of digits 2-5 - Innervation: Anterior Interosseous nerve C7-T1 = index+ middle
: Ulnar nerve C8-T1 = ring + little
Flexor Pollucis Longus (FPL)
- Position: lateral to FDP in deep layer of anterior compartment
- Origin: Anterior surface of radius (+adjacent IM)
- Insertion: Palmar base of distal phalanx of thumb
- Action: assists wrist flexion
: CMC, MCP, IP flexion of thumb - Innervation: Anterior Interosseous Nerve C8-T1
Extensor Carpi Radialis Longus (ECRL)
- Position: lateral side of superficial posterior compartment - partly deep to brachioradialis
- Origin: Lateral supracondylar ridge of humerus
- Insertion: Dorsal base of metacarpal 2
- Action: Extends wrist
: Abduction of wrist - Innervation: Radial nerve C6-7
(radial nerve splits between ECRL = ECRB)
Extensor Carpi Radialis Brevis (ECRB)
- Position: Superficial posterior compartment, adjacent and partly covered by ECRL
- Origin: common extensor tendon (lateral epicondyle)
- Insertion: Dorsal base of metacarpal 3
- Action: Wrist extension
: Wrist abduction - Innervation: Posterior Interosseous Nerve C6-7
Extensor Carpi Ulnaris (ECU)
- Position: Posteromedial aspect of superficial posterior compartment
- Origin; Common extensor tendon (lateral epicondyle)
- Insertion: via shared aponeurosis with fdp + fcu from posterior border of ulna to medial base of 5th mc
- Action: wrist adduction
: wrist extension - Innervation: Posterior Interosseous Nerve C7-8
Extensor Digitorum (ED)
- Position: central, superficial in posterior compartment
- Origin: Common extensor tendon (lateral epicondyle)
- Insertion: 4 tendons to base of middle and distal phalanges of digits 2-5 (via digital dorsal expansion)
- Action: Extension of MCP joints of digits 2-5
: assists extension of IP joints of digits 2-5
: assists wrist extension - Innervation: Posterior Interosseous Nerve C7-8
Extensor Digiti Minimi (EDM)
- Position: medial to ED in superficial posterior compartment
- Origin: Common extensor tendon (lateral epicondyle)
- Insertion: extensor hood of little finger - ulna side to ED tendon
- Action: Extension at MCP of little finger
: assists extension of IP joints of little finger
: assists wrist extension - Innervation: Posterior Interosseous Nerve C7-8