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