Forearm+Hand Muscles

Forearm (Antebrachium)

radius and ulna

muscles that cross over elbow

muscles that cross over wrist joint

Movements of Wrist Joint

flexion

extension

pronation

supination

Flexors+Extensors Hints

cross anterior side of joint→flexion

cross posterior side of joint→extension

Brachialis Origin

anterior aspect of humerus

Brachialis Insertion

tuberosity of the ulna

Brachialis Innervation

musculocutaneous nerve

Brachialis Function

flexion of the forearm at elbow joint

Brachioradialis Origin

lateral edge of humerus above lateral epicondyle

Brachioradialis Insertion

lateral side of radius (distal end)

Brachioradialis Innervation

radial nerve

Brachioradialis Function

flexion of the elbow

Muscles that Flex the Elbow

biceps brachii

brachialis

brachioradialis

Muscles that Extend the Elbow

triceps brachii

anconeus

Triceps Brachii Origin

long head→infraglenoid tubercle of scapula

medial+lateral heads→posterior surface of humerus

Triceps Brachii Insertion

olecranon of the ulna

Triceps Brachii Innervation

radial nerve

Triceps Brachii Function

extension of forearm at elbow joint

extension of arm at glenohumeral joint

adduction of arm at glenohumeral joint

Anconeus Origin

lateral epicondyle of the humerus

Anconeus Insertion

lateral side of the olecranon of the ulna

Anconeus Innervation

radial nerve

Anconeus Function

extension of the forearm at elbow joint

abduction of the ulna (in pronation)

Muscles that Pronate the Forearm

pronator teres

pronator quadratus

Pronator Teres Origin

humeral head→medial epicondyle of the humerus

ulnar head→coronoid process of the ulna

Pronator Teres Insertion

lateral side of the radius (midbone)

Pronator Teres Innervation

median nerve

mediaN

Pronator Teres Function

pronation of the forearm

Pronator Quadratus Origin

distal surface of the ulna

Pronator Quadratus Insertion

distal anterior surface of the radius

Pronator Quadratus Innervation

median nerve (aka: anterior interosseous nerve)

mediaN

Pronator Quadratus Function

pronation of the forearm

Muscles that Supinate the Forearm

supinator

biceps brachii

Supinator Origin

Superficial

• lateral epicondyle of humerus

• radial+collateral+annular ligaments

deep→ulna

Supinator Insertion

lateral surface of the radius

Supinator Innervation

posterior interosseous nerve

Supinator Function

supination

Biceps Brachii Function

flexion of the forearm at the elbow joint

supination of the forearm

aids flexion at the glenohumeral joint

Extensors of the Wrist

to the dorsal/posterior surface of the hand

dorsal side of hand→extensors

• extensor carpi radialis longus

• extensor carpi radialis brevis

• extensor carpi ulnaris

Extensor Carpi Radialis Longus Origin

ridge above lateral epicondyle of the humerus

Extensor Carpi Radialis Longus Insertion

dorsal surface of the base of metacarpal II

Extensor Carpi Radialis Longus Innervation

radial nerve

Extensor Carpi Radialis Longus Function

extends wrist

abducts wrist

Extensor Carpi Radialis Brevis Origin

lateral epicondyle of the humerus

Extensor Carpi Radialis Brevis Insertion

dorsal surface of the base of metacarpals II and III

Extensor Carpi Radialis Brevis Innervation

radial nerve (deep branch)

Extensor Carpi Radialis Brevis Function

extends wrist

abducts wrist

Extensor Carpi Ulnaris Origin

lateral epicondyle of the humerus

posterior border of the ulna

Extensor Carpi Ulnaris Insertion

dorsal surface of the base of medial side metacarpal V

Extensor Carpi Ulnaris Innervation

radial nerve

Extensor Carpi Ulnaris Function

extends wrist

adducts wrist

Flexors of the Wrist

all insert into the palmar surface of the hand

• flexor carpi radialis

• flexor carpi ulnaris

• palmaris longus

towards thumb→medial

Flexor Carpi Radialis Origin

medial epicondyle of humerus

Flexor Carpi Radialis Insertion

palmar surface of base of metacarpals II and III

Flexor Carpi Radialis Innervation

median N

mediaN

Flexor Carpi Radialis Function

flexion of the wrist joint

abduction of the wrist joint

Flexor Carpi Ulnaris Origin

humeral head→medial epicondyle of humerus

ulnar head→olecranon of ulna

Flexor Carpi Ulnaris Insertion

pisiform

hamate

palmar surface base of metacarpal V

Flexor Carpi Ulnaris Innervation

ulnar nerve

Flexor Carpi Ulnaris Function

flexion of the wrist joint

adduction of the wrist joint

Palmaris Longus Origin

medial epicondyle of humerus

Palmaris Longus Insertion

palmar aponeurosis of hand

Palmaris Longus Innervation

median nerve

mediaN

Palmaris Longus Function

flexion of the wrist joint

Palmaris Longus Rarity

absent→15% of population

1. slightly flexion of wrist

2. cup palm

3. oppose thumb to remaining 4 fingers (italian hand gesture)

see/feel 2 ridges under skin in middle of wrist→palmaris longus

Extrinsic Extensors of the Fingers

posterior/dorsal surface of the hand

• extensor digitorum

• extensor indices

• extensor digiti minimi

Extensor Digitorum Origin

lateral epicondyle of the humerus

Extensor Digitorum Insertion

tendons to dorsal surface of the bases of the middle+distal phalanges of digits 2-5

Extensor Digitorum Innervation

posterior interosseous nerve (branch off radial nerve)

Extensor Digitorum Function

extends digits 2-5

extend the wrist

Extensor Indices Origin

distal part of the posterior ulnar shaft

Extensor Indices Insertion

tendons to extensor hood of 2nd digit

Extensor Indices Innervation

posterior interosseous nerve (branch off radial nerve)

Extensor Indices Function

extends digit 2

Extensor Digiti Minimi Origin

lateral epicondyle of humerus

Extensor Digiti Minimi Insertion

tendons to attach to extensor hood of 5th digit

Extensor Digiti Minimi Innervation

posterior interosseous nerve (branch off radial nerve)

Extensor Digiti Minimi Function

extends digit 5

Extrinsic Flexors of the Fingers

posterior/dorsal surface of the hand

• flexor digitorum superficialis

• flexor digitorum profundus (deep to FD superficialis)

Flexor Digitorum Superficialis Origin

medial epicondyle of the humers

radius

coronoid process of the ulna

Flexor Digitorum Superficialis Insertion

4 tendons attach to palmar surfaces of middle phalanges of digits 2-5

(tendons split distally towards fingers→“snake tongue”)

“ssssuperficialis, ssssnake tongue”

Flexor Digitorum Superficialis Innervation

median nerve

mediaN

Flexor Digitorum Superficialis Function

flexion of proximal interphalangeal joint of digits 2-5

flexion of metacarpophalangeal joints

flex wrist

Flexor Digitorum Profundus Origin

anterior+medial surfaces of the ulna

anterior medial half of interosseous membrane

Flexor Digitorum Profundus Insertion

4 tendons attach to palmar surfaces of distal phalanges of digits 2-5

Flexor Digitorum Profundus Innervation

median nerve (mediaN)

ulnar nerve

Flexor Digitorum Profundus Function

flexion of distal interphalangeal joint of digits 2-5

flexion of metacarophalangeal joint

flex wrist joint

Extrinsic Muscles that Move the Thumb

thumb-side (lateral)

extensors

• extensor pollicis longus

• extensor pollicis brevis

flexors

• flexor pollicis longus

• abductor pollicis longus

Extensor Pollicis Longus Origin

shaft of ulna

interosseous membrane

Extensor Pollicis Longus Insertion

dorsal surface of base of distal phalanx of thumb

Extensor Pollicis Longus Innervation

posterior interosseous nerve

Extensor Pollicis Longus Function

extension of interphalangeal joint of the thumb

extension of carpometacarpal+metacarpophalangeal joints of the thumb

Extensor Pollicis Brevis Origin

posterior surface of the radius

radial half of the interosseous membrane

Extensor Pollicis Brevis Insertion

dorsal surface of the base of the proximal phalanx of the thumb

Extensor Pollicis Brevis Innervation

posterior interosseous nerve

Extensor Pollicis Brevis Function

extension of metacarpophalangeal joint of the thumb

extesnion of the carpometacarpal joint of the thumb

Flexor Pollicis Longus Origin

anterior surface of the radius

radial half of the interosseous membrane

Flexor Pollicis Longus Insertion

palmar surface of the distal phalanx of the thumb

Flexor Pollicis Longus Innervation

anterior interosseous nerve (branch off median nerve)

mediaN

Flexor Pollicis Longus Function

flex interphalangeal joint of the thumb

flex metacarpophalangeal joint of the thumb

Abductor Pollicis Longus Origin

posterior surface of radius and ulna

interosseous membrane

Abductor Pollicis Longus Insertion

lateral side of the base of the first metacarpal