Radial Nerve

Authors
Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Left Humerus (Posterior view)

Origin

Nerve roots: C5-T1

Motor branches

elbow extensors—the triceps brachii and anconeus—have a single source of nerve supply through the radial nerve

Direct Muscular branches to:

  • Brachialis (partial)
  • Triceps brachii
  • Anconeus
  • Brachioradialis
  • Extensors carpi radialis longus (ECRL)
  • Extensors carpi radialis brevis (ECRB)

Indirect Muscular branches via Posterior Interosseous Nerve

  • Supinator
  • Extensor digitorum
  • Extensor digiti minimi
  • Extensor carpi ulnaris
  • Extensors pollicis brevis
  • Extensors pollicis longus
  • Extensor indicis
  • Abductor pollicis longus
Table 1: Radial Nerve Muscle Innervations
Muscle Origin Insertion Innervation Action
Abductor pollicis longus Dorsal Radius
Dorsal Ulna
IO membrane		 1st metacarpal base Radial n.
C7 - C8		 Radiocarpal joint: Radial dev.
CMC & 1st MCP: Abduction
Anconeus GHJ joint capsule Olecranon of Ulna (radial surface) Radial n.
C6 - C8		 Elbow: Extension, Tightens joint
Brachialis Distal half of anterior Humerus Ulnar tuberosity Musculocutaneous n.
Radial n.
C5 - C7		 Elbow: Flexion
Brachioradialis Lateral distal humerus
Lateral intermuscular septum		 Styloid process of Radius Radial n.
C5 - C6		 Elbow: Flexion, Semipronation (to 90°)
Extensor carpi radialis brevis Lateral epicondyle of Humerus 3rd metacarpal base Radial n.
C7 - C8		 Elbow: Weak flexion
Wrist: Extension, Radial deviation
Extensor carpi radialis longus Lateral supracondylar ridge
Lateral intermuscular septum		 2nd metacarpal base Radial n.
C6 - C7		 Elbow: Weak flexion
Wrist: Extension, Radial deviation
Extensor carpi ulnaris Lateral epicondyle of Humerus
Ulnar head		 5th metacarpal base Radial n.
C7 - C8		 Wrist: Extension, Ulnar deviation
Extensory digiti minimi Lateral epicondyle of Humerus 5th Dorsal digital expansion Radial n.
C7 - C8		 Wrist: Extension, Ulnar deviation
5th MCP, PIP, DIP: Extension, Abduction
Extensor digitorum Lateral epicondyle of Humerus 2-5th Dorsal digital expansion Radial n.
C7 - C8		 Wrist: Extension
2-5 MCP, PIP, DIP: Extension
Extensor indicis Posterior Ulna
IO membrane		 2nd Dorsal digital expansion Radial n.
C7 - C8		 Wrist: Extension
2nd MCP, PIP, DIP: Extension
Extensor pollicis brevis Radius (posterior)
IO membrane		 Base of 1st proximal phalanx Radial n.
C7 - C8		 Radiocarpal joint: Radial dev.
1st CMC & MCP: Extension
Extensor pollicis longus Dorsal ulna
IO membrane		 Base of 1st Distal phalanx Radial n.
C7 - C8		 Wrist: Extension, Radial dev.
CMC: Abduction
1st MCP & IP: Extension
Supinator Olecranon
Lateral epicondyle
Radial collateral lig.
Annular lig.		 Radius (between radial tuberosity and pronator teres) Radial n.
C6 - C7		 Radioulnar joints: Supination
Triceps brachii lateral head Posterior humerus just *proximal* to radial groove
Lateral intermuscular septum		 Olecranon of Ulna Radial n.
C6 - C8		 Elbow: Extension
Triceps brachii Long head Infraglenoid tubercle of Scapula Olecranon of Ulna Radial n.
C6 - C8		 Elbow: Extension
GHJ: Extension, Adduction
Triceps brachii medial head Posterior humerus just distal to radial groove
Medial intermuscular septum		 Olecranon of Ulna Radial n.
C6 - C8		 Elbow: Extension

Cutaneous Branches

Radial Nerve Cutaneous Branches2

Radial Nerve Cutaneous Branches
  • Articular brs. from radial n.: Capsule of the shoulder joint
  • Articular brs. from posterior interosseous n.: Joint capsule of the wrist and four radial metacarpophalangeal joints
  • Posterior brachial cutaneous n. 
  • Inferior lateral brachial cutaneous n. 
  • Posterior antebrachial cutaneous n.

Superficial Branches

  • Dorsal digital nn.
  • Ulnar communicating br.

Pathway

  • Originates from the posterior cord of the brachial plexus

  • Passes through Triceps hiatus (“triangular interval”)

  • Passes between the brachioradialis and brachialis muscles.

Treatment

Entrapment

Reading list
  • Radial nerve p373

References

1.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
2.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
3.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
4.
Jones B. B Project Foundations. b Project; 2025.
5.
Kolar P. Clinical Rehabilitation. 1st ed. Dynamic Neurological Stabilization; 2014.

Citation

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