Brachium to Hand Musculature

Muscle Regions of the Body:

• Head and neck
• Trunk, front and back
• Brachium, antibrachium & hand
• Thigh, leg & foot

• Brachium
• Antebrachial Flexors
• Antebrachial Extensors
• Hand & Wrist

Links Related to this Region:

• Radiographic Osteology of the Shoulder
• Radiographic Osteology of the Hand

Brachium Musculature

Coracobrachialis

• Origin: coracoid process of the scapula
• Insertion: medial shaft of the humerus at about its middle
• Action:
  1. flexes the humerus
  2. assists to adduct the humerus
• Blood: muscular branches of the brachial artery
• Nerve: musculocutaneous nerve, C5,6,(C7)

Biceps brachii

• Origin:
  1. long head- supraglenoid tubercle and glenohumeral labrum
  2. short head- tip of the coracoid process of the scapula
• Insertion:
  1. radial tuberosity
  2. bicipital aponeurosis
• Action:
  1. flexes the forearm at the elbow (when supinated)
  2. supinates forearm from neutral
  3. stabilizes anterior aspect of shoulder
  4. flexes shoulder (weak if at all)
• Blood: muscular branches of brachial artery
• Nerve: musculocutaneous nerve, C5,6

Brachialis

• Origin:
  1. lower 1/2 of anterior humerus
  2. both intermuscular septa
• Insertion:
  1. ulnar tuberosity
  2. coronoid process of ulna slightly
• Action: elbow flexion (major mover)
• Blood:
  1. muscular branches of brachial artery
  2. radial recurrent artery
• Nerve: musculocutaneous nerve, C5,6

Triceps brachii

• Origin:
  1. long head - infraglenoid tubercle of the scapula
  2. lateral head - upper half of the posterior surface of the shaft of the humerus, and the upper part of the lateral intermuscular septum
  3. medial head - posterior shaft of humerus, distal to radial groove and both the medial and lateral intermuscular septum (deep to the long & lateral heads)
• Insertion:
  1. posterior surface of the olecranon process of the ulna
  2. deep fascia of the antebrachium
• Action:
  1. long - adducts the arm, extends at the shoulder, and a little elbow flexion
  2. lateral - extends the forearm at the elbow
  3. medial - extends the forearm at the elbow
• Blood:
  1. muscular branches of the brachial artery
  2. superior ulnar collateral artery
  3. profunda brachii artery
• Nerve: radial nerve, C6,7

Anconeus

• Origin: posterior surface of the lateral epicondyle of the humerus
• Insertion: lateral aspect of olecranon extending to the lateral part of ulnar body
• Action:
  1. extends the forearm at the elbow
  2. supports the elbow when in full extension
• Blood: middle collateral artery from the profunda brachii artery
• Nerve: radial nerve, C7,8

Antebrachial Flexor Musculature

Pronator teres

• Origin:
  1. humeral head:
     1. upper portion of medial epicondyle via the CFT (common flexor tendon)
     2. medial brachial intermuscular septum
  2. ulnar head - coronoid process of ulna
  3. antebrachial fascia
• Insertion: lateral aspect of radius at the middle of the shaft (pronator tuberosity)
• Action:
  1. pronates forearm (during rapid or forced pronation)
  2. weakly flexes the elbow
• Blood:
  1. muscular branches of ulnar artery
  2. muscular branches of radial artery
• Nerve: median nerve, C6,7

Flexor carpi radialis

• Origin:
  1. medial epicondyle via the CFT (common flexor tendon)
  2. antebrachial fascia
• Insertion: base of the 2nd and sometimes 3rd metacarpals
• Action:
  1. flexes the hand at the wrist
  2. radially deviates the wrist
  3. may assist to pronate the forearm
• Blood: muscular branches of radial artery
• Nerve: median nerve, C6,7

Palmaris longus

• Origin:
  1. medial epicondyle via the CFT (common flexor tendon)
  2. antebrachial fascia
• Insertion:
  1. central portion of the flexor retinaculum
  2. superficial portion of the palmar aponeurosis
• Action: flexes the hand at the wrist
• Blood: muscular branches of ulnar artery
• Nerve: median nerve, C6,7

Flexor carpi ulnaris

• Origin:
  1. humeral head - medial epicondyle via the CFT (common flexor tendon)
  2. ulnar head:
     1. medial aspect of olecranon
     2. proximal 3/5 of dorsal ulnar shaft
     3. antebrachial fascia
• Insertion:
  1. pisiform & hamate bones (via the pisohamate ligament)
  2. base of the 5th metacarpal (via the pisometacarpal ligament)
• Action:
  1. flexes the hand at the wrist
  2. ulnarly deviates the wrist
  3. stabilizes wrist to permit powerful thumb motion
• Blood: muscular branches of ulnar artery
• Nerve: ulnar nerve, C8,T1

Flexor digitorum superficialis

• Origin:
  1. humeral-ulnar head:
     1. medial epicondyle via the CFT (common flexor tendon)
     2. medial boarder of base of coronoid process of ulna
     3. medial (ulnar) collateral ligament
     4. antebrachial fascia
  2. radial head: oblique line of radius along its upper anterior boarder
• Insertion: both sides of the base of each middle phalanx of the 4 fingers
• Action:
  1. flexes the proximal and middle phalanges
  2. flexes the wrist if fingers are extended
• Blood:
  1. muscular branches of ulnar artery
  2. muscular branches of radial artery
• Nerve: median nerve, C7,8,T1

Flexor digitorum profundus

• Origin:
  1. anterior & medial surface of upper 3/4 ulna
  2. adjacent interosseous membrane
• Insertion: distal phalanx of medial 4 digits (through FDS tunnel)
• Action:
  1. flexes the distal IP joints and in so doing flexes the proximal and middle IP joints
  2. flexes the wrist if fingers are extended
• Blood:
  1. muscular branches of the ulnar artery
  2. muscular branches of the radial artery
  3. anterior interosseous artery (from ulnar artery)
• Nerve:
  1. medial portion - ulnar nerve, C8,T1
  2. lateral portion - anterior interosseous branch of median nerve, C8,T1

Flexor pollicis longus

• Origin:
  1. middle anterior surface of the radius
  2. interosseous membrane
  3. (may also originate from lateral boarder of coronoid process
  4. or medial epicondyle)
• Insertion: palmar aspect of base of the distal phalanx of thumb (deep to flexor retinaculum)
• Action:
  1. flexes the distal phalanx of the thumb (IP joint)
  2. flexes the other joints to the wrist (McP, CMc and weakly at the wrist)
• Blood:
  1. muscular branches of radial artery
  2. anterior interosseous artery
• Nerve: anterior interosseous branch of median nerve, C8,T1

Pronator quadratus

• Origin: distal 1/4 anteriomedial surface of ulna
• Insertion: distal 1/4 anteriolateral surface of radius
• Action: pronates the forearm and hand
• Blood:
  1. anterior interosseous artery
  2. muscular branches of the radial artery
• Nerve: anterior interosseous branch of median nerve, C8,T1

Antebrachial Extensor Musculature

Brachioradialis

• Origin:
  1. upper lateral supracondylar ridge of humerus (between the triceps and brachialis muscles)
  2. lateral intermuscular septum of humerus
• Insertion:
  1. superior aspect of styloid process of radius
  2. lateral side of the distal 1/2 to 1/3 of the radius
  3. antebrachial fascia
• Action:
  1. flexes the forearm at the elbow
  2. pronates the forearm when supinated
  3. supinates the forearm when pronated
• Blood: radial recurrent artery
• Nerve:
  1. radial nerve, C5,6 OR
  2. deep branch of the radial nerve

Extensor carpi radialis longus

• Origin:
  1. lower lateral supracondylar ridge (below the brachioradialis)
  2. lateral intermuscular septum of humerus
• Insertion: base of 2nd metacarpal
• Action:
  1. extends the hand at the wrist
  2. radially deviates the hand at the wrist
  3. weakly flexes the forearm at the elbow
  4. weakly supinates the forearm
• Blood: radial recurrent artery
• Nerve:
  1. radial nerve, C5,6 OR
  2. deep branch of the radial nerve

Extensor carpi radialis brevis

• Origin:
  1. lateral epicondyle via the CET (common extensor tendon)
  2. radial collateral ligament
  3. antebrachial fascia
• Insertion: base of 3rd metacarpal
• Action:
  1. extends the hand at the wrist
  2. radially deviates the hand at the wrist
• Blood: radial recurrent artery
• Nerve: deep branch of the radial nerve, C6,7

Extensor digitorum

• Origin:
  1. lateral epicondyle via the CET (common extensor tendon)
  2. antebrachial fascia
• Insertion:
  1. base of middle phalanx of each of the four fingers (central band)
  2. base of distal phalanx of each of the four fingers (2 lateral bands)
• Action:
  1. extends the four medial digits
  2. extends the wrist if fingers flexed
  3. abducts the digits (spreads the digits as it extends them)
• Blood: posterior interosseous artery
• Nerve: posterior interosseous nerve of the radial nerve, C6,7,8

Extensor digiti minimi

• Origin:
  1. lateral epicondyl via the CET (common extensor tendon)
  2. antebrachial fascia
  3. ulnar aspect of extensor digitorum
• Insertion:
  1. base of middle phalanx of the 5th digit (central band)
  2. base of distal phalanx of the 5th digit (2 lateral bands)
• Action:
  1. extends the 5th digit
  2. abducts the 5th digit
• Blood: posterior interosseous artery
• Nerve: posterior interosseous nerve of the radial nerve, C6,7,8

Extensor carpi ulnaris

• Origin:
  1. 1st head - lateral epicondyle via the CET (common extensor tendon)
  2. 2nd head - posterior body of ulna
  3. antebrachial fascia
• Insertion: medial side of base of the 5th metacarpal
• Action:
  1. extends the hand at the wrist
  2. ulnarly deviates the hand at the wrist
• Blood: posterior interosseous artery
• Nerve: posterior interosseous nerve of the radial nerve, C6,7,8

Supinator

• Origin:
  1. lateral epicondyle of humerus
  2. supinator crest of ulna
  3. radial collateral ligament
  4. annular ligament
  5. antebrachial fascia
• Insertion: proximal portion of anteriorlateral surface of the radius
• Action: supinates the forearm
• Blood: radial recurrent artery
• Nerve: deep branch of the radial nerve, C6

Abductor pollicis longus

• Origin:
  1. posterior surfaces of ulna and radius
  2. interosseous membrane
  3. antebrachial fascia
• Insertion: lateral aspect of base of 1st metacarpal
• Action:
  1. abducts the 1st metacarpal
  2. assists to extend & rotate the thumb
  3. radially deviates the hand at the wrist
  4. flexes the hand at the wrist
• Blood: posterior interosseous artery
• Nerve: posterior interosseous nerve of the radial nerve, C6,7,(C8)

Extensor pollicis brevis

• Origin:
  1. posterior surfaces of radius (below abductor pollicis longus)
  2. interosseous membrane
  3. antebrachial fascia
• Insertion: base of proximal phalanx of thumb (often a slip inserts into extensor pollicis longus tendon)
• Action:
  1. extends the proximal phalanx and 1st metacarpal of the thumb
  2. radially deviates the hand at the wrist
• Blood: posterior interosseous artery
• Nerve: posterior interosseous nerve of the radial nerve, C6,7,(C8)

Extensor pollicis longus

• Origin:
  1. posterior surface of ulna
  2. interosseous membrane
  3. antebrachial fascia
• Insertion: distal phalanx of thumb
• Action:
  1. extends distal phalanx of thumb
  2. extends proximal phalanx of thumb
  3. assists to extend the hand at the wrist (if fingers flexed)
• Blood: posterior interosseous artery
• Nerve: posterior interosseous nerve of the radial nerve, C6,7,8

Extensor indicis

• Origin:
  1. posterior surface of ulna (distal to extensor pollicis longus)
  2. interosseous membrane
  3. antebrachial fascia
• Insertion: base of middle and distal phalanx of the index finger
• Action:
  1. extends the 2nd digit (McP & IP joints)
  2. adducts the 2nd digit
  3. assists to extend the hand at the wrist
  4. stabilizes McP joint for flexion of IP solely
• Blood: posterior interosseous artery
• Nerve: posterior interosseous nerve of the radial nerve, C6,7,8

Hand & Wrist Musculature

Abductor pollicis brevis

• Origin:
  1. distal border of flexor retinaculum
  2. trapezium (may be variable)
• Insertion:
  1. lateral aspect of base of proximal phalanx of the thumb
  2. may also send a slip to the tendon of extensor pollicis longus
• Action:
  1. abducts thumb (at the McP joint)
  2. participates to flex the thumb (at the McP joint)
  3. if attached to extensor pollicis longus, it might assist to extend the thumb
• Blood: superficial palmar branches of radial artery
• Nerve: recurrent branch of median nerve, C8,T1

Flexor pollicis brevis

• Origin:
  1. superficial head:
     1. distal border of flexor retinaculum
     2. trapezium
  2. deep head:
     1. floor of carpal tunnel
     2. indirectly to scaphoid & trapezium
• Insertion:
  1. base of proximal phalanx of thumb
  2. can also attach to the lateral sesamoid bone at the McP joint
• Action: powerfully flexes the thumb (at the McP joint)
• Blood: superficial palmar branches of radial artery
• Nerve:
  1. superficial head - recurrent branch of median nerve, C8,T1
  2. deep head - deep branch of ulnar nerve, C8,T1

Opponens pollicis

• Origin:
  1. distal border of flexor retinaculum
  2. trapezium
• Insertion: lateral aspect of the 1st metacarpal
• Action: opposes the thumb to the fingers
• Blood: superficial palmar branches of radial artery
• Nerve: recurrent branch of median nerve, C8,T1

Adductor pollicis

• Origin:
  1. transverse head: 3rd metacarpal
  2. oblique head:
     1. base of 1st, 2nd and 3rd metacarpals
     2. floor of carpal tunnel
• Insertion:
  1. medial aspect of the base of proximal phalanx
  2. medial sesamoid at McP
• Action:
  1. adducts the thumb
  2. may assist to flex the thumb (at the McP joint)
• Blood: superficial palmar branches of radial artery
• Nerve: deep branch of ulnar nerve, C8,T1

Palmaris brevis

• Origin: medial margin of palmar aponeurosis
• Insertion:
  1. skin of ulnar border of palm
  2. may insert on the pissiform
• Action: tenses the skin on the ulnar side, which is used in a grip action
• Blood: superficial palmar branches of ulnar artery
• Nerve: superficial branch of ulnar nerve, C8,T1

Abductor digiti minimi

• Origin: pisiform & tendon of flexor carpi ulnaris
• Insertion:
  1. medial aspect of the base of proximal phalanx of the 5th digit
  2. may send a slip to the ulnar side of the dorsal expansion
• Action:
  1. abduct 5th digit (requires pisiform stabilized by FCU)
  2. assists to flex the 5th digit (at McP)
  3. may assist in extension of 5th digit (at IP due to slips to extensor digitorum)
• Blood: deep palmar branches of ulnar artery
• Nerve: deep branch of ulnar nerve, C8,T1

Flexor digiti minimi brevis

• Origin:
  1. distal border of flexor retinaculum
  2. hook of the hamate
• Insertion: medial aspect of the base of proximal phalanx
• Action: flexes the 5th digit (at the McP joint)
• Blood: deep palmar branches of ulnar artery
• Nerve: deep branch of ulnar nerve, C8,T1

Opponens digiti minimi

• Origin:
  1. distal border of flexor retinaculum
  2. hook of the hamate
• Insertion: medial aspect of the 5th metacarpal
• Action:
  1. opposes the 5th digit with the thumb
  2. assists to "cup" the palm
• Blood: deep palmar branches of ulnar artery
• Nerve: deep branch of ulnar nerve, C8,T1

Palmar interossei

• Origin: from the side of the metacarpal that faces the midline - to adduct them
• Insertion:
  1. on the base of the proximal phalanx of the digit of origin (same side toward the midline)
  2. extensor hood of the same digit(s)
• Action:
  1. adducts the fingers (hint: PAD)
  2. flexes the fingers (at the McP while IP joints are extended)
• Blood: palmar metacarpal artery of deep palmar arch
• Nerve: deep branch of ulnar nerve, C8,T1

Dorsal interossei

• Origin: between each metacarpal
• Insertion:
  1. directly distal to the origin on the base of the proximal phalanx closest to the midline (to abduct them.)
  2. extensor hood of the same digit(s)
• Action:
  1. abducts the fingers (hint: DAB)
  2. flexes the fingers (at the McP while IP joints are extended)
• Blood: palmar metacarpal artery of deep palmar arch
• Nerve: deep branch of ulnar nerve, C8,T1

Lumbricals

• Origin:
  1. tendon of flexor digitorum profundus
  2. 1 & 2 have a single head of origin (from radial aspect of tendon)
  3. 3 & 4 have two heads of origin (each head from an adjacent tendon)
• Insertion: extensor hood of digits 2-5
• Action:
  1. flexes the fingers (at the McP joints)
  2. extend IPs
• Blood: palmar metacarpal arteryof deep palmar arch
• Nerve:
  1. 1 & 2 - median nerve, C8,T1
  2. 3 & 4 - deep branch of ulnar nerve, C8,T1

© 1998 by Darryl Hosford, all rights reserved.