Upper Extremity Musculature: Origins, Insertions, Actions, and Innervations

Anterior Arm Musculature

• Biceps Brachii

  • Origin:
  • Short head: Coracoid process of scapula
  • Long head: Supraglenoid tubercle of scapula
  • Insertion: Radial tuberosity and bicipital aponeurosis
  • Action:
  • Flex the elbow
  • Supinate the forearm
  • Flex the shoulder
  • Innervation: Musculocutaneous n.

• Brachialis

  • Origin: Distal half of anterior surface of humerus
  • Insertion: Ulnar tuberosity and coronoid process of ulna
  • Action: Flex the elbow
  • Innervation: Musculocutaneous n., small branch from radial n.

Posterior Arm and Elbow Musculature

• Triceps Brachii

  • Origin:
  • Long head: Infraglenoid tubercle of scapula
  • Lateral head: Posterior surface of proximal half of the humerus
  • Medial head: Posterior surface of distal half of the humerus
  • Insertion: Olecranon process of ulna
  • Action:
  • All heads: Extend the elbow
  • Long head: Extend the shoulder, Adduct the shoulder
  • Innervation: Radial n.

• Anconeus

  • Origin: Lateral epicondyle of the humerus
  • Insertion: Olecranon process and posterior, proximal surface of ulna
  • Action: Extend the elbow
  • Innervation: Radial nerve

Forearm Musculature: Brachioradialis and Rotators

• Brachioradialis

  • Origin: Proximal two-thirds of the lateral supracondylar ridge of humerus
  • Insertion: Radial styloid
  • Action: Flex the elbow, assist to pronate and supinate the forearm when these movements are resisted
  • Innervation: Radial n.

• Supinator

  • Origin: Lateral epicondyle of humerus, radial collateral and annular ligaments, supinator crest of ulna
  • Insertion: Anterior, lateral, surface of proximal one-third of radial shaft
  • Action: Supinate the forearm
  • Innervation: Radial nerve

• Pronator Teres

  • Origin: Common flexor tendon from medial epicondyle of humerus and coronoid process of ulna
  • Insertion: Middle of lateral surface of radius
  • Action:
  • Pronate the forearm
  • Assist to flex the elbow
  • Innervation: Median nerve

• Pronator Quadratus

  • Origin: Medial, anterior surface of distal ulna
  • Insertion: Lateral, anterior surface of distal radius
  • Action: Pronate the forearm
  • Innervation: Median nerve

Superficial Forearm and Wrist Flexors

• Flexor Carpi Radialis

  • Origin: Common flexor tendon from medial epicondyle of humerus
  • Insertion: Bases of 2nd and 3rd metacarpals
  • Action:
  • Flex the wrist
  • Radially deviate the wrist
  • May assist to flex the elbow
  • Innervation: Median n.

• Palmaris Longus

  • Origin: Common flexor tendon from medial epicondyle of humerus
  • Insertion: Flexor retinaculum and palmar aponeurosis
  • Action:
  • Tense the palmar fascia
  • Flex the wrist
  • May assist to flex the elbow
  • Innervation: Median n.

• Flexor Carpi Ulnaris

  • Origin:
  • Humeral head: Common flexor tendon from medial epicondyle of humerus
  • Ulnar head: Posterior surface of proximal two thirds of ulna
  • Insertion: Pisiform, hook of hamate, and base of the 5th metacarpal
  • Action:
  • Flex the wrist
  • Ulnarly deviate the wrist
  • Assist to flex the elbow
  • Innervation: Ulnar n.

Forearm Musculature: Digital Flexors

• Flexor Digitorum Superficialis

  • Origin: Common flexor tendon from medial epicondyle of humerus, ulnar collateral ligament, coronoid process of ulna, interosseous membrane, and proximal shaft of radius
  • Insertion: Sides of middle phalanges of 2nd through 5th fingers
  • Action:
  • Flex the 2nd through 5th fingers (metacarpophalangeal and proximal interphalangeal joints)
  • Flex the wrist
  • Innervation: Median n.

• Flexor Digitorum Profundus

  • Origin: Anterior and medial surfaces of proximal three quarters of ulna
  • Insertion: Bases of distal phalanges, volar surface of 2nd through 5th fingers
  • Action:
  • Flex the 2nd through 5th fingers (metacarpophalangeal and distal interphalangeal joints)
  • Assist to flex the wrist
  • Innervation:
  • 2nd and 3rd fingers: Median n.
  • 4th and 5th fingers: Ulnar n.