The elbow serves as the central link in the kinetic chain of the upper extremity. The management of elbow symptoms requires a thorough appreciation of the intricate anatomy and biomechanics of the joint complex to diagnose the cause of these symptoms correctly.
The elbow joint comprises three distinct articulations: the ulnohumeral, radiohumeral (radiocapitellar), and proximal radioulnar joints.
- The ulnohumeral and radiohumeral joints provide flexion/extension of the elbow and pronation/supination of the forearm.
- The proximal radioulnar joint works in conjunction with the distal radioulnar joint at the wrist to achieve forearm pronation and supination.
The movements of the elbow complex, produced by muscle action (Tables 6-1 and 6-2), include flexion and extension of the elbow, and pronation and supination of the forearm. Stability of the elbow complex during these movements is provided by the osseous relationships and by medial and lateral ligament complexes (Table 6-3).
Table 6-1 Muscle Compartments of the Forearm |Favorite Table|Download (.pdf)
Table 6-1 Muscle Compartments of the Forearm
|Compartment||Principal Muscles||Action||Peripheral Nerve Innervation||Nerve Root Derivation|
|Anterior||Pronator teres||Pronation of the forearm||Median||C6–C7|
|Flexor carpi radialis||Pronation of the forearm||Median||C6–C7|
|Flexor digitorum superficialis||Flexion of the fingers||Ulnar: medial two digits||C7–C8, T1|
|Flexor digitorum profundus||Flexion of the fingers||Anterior interosseous (median)||C8, T1|
|Flexor pollicis longus||Flexion of the thumb||Superficial head: median (lateral terminal branch)||C8, T1|
|Flexor carpi ulnaris||Ulnar deviation of the wrist||Ulnar||C7–C8|
|Pronator quadratus||Pronation of the forearm||Anterior interosseous (median)||C8, T1|
|Posterior||Abductor pollicis longus||Extension of the thumb||Posterior interosseous (radial)||C7–C8|
|Extensor pollicis brevis||Extension of the thumb||Posterior interosseous (radial)||C7–C8|
|Extensor pollicis longus||Extension of the thumb||Posterior interosseous (radial)||C7–C8|
|Extensor digitorum communis||Extension of the fingers||Posterior interosseous (radial)||C7–C8|
|Extensor digiti minimi||Extension of the little finger||Posterior interosseous (radial)||C7–C8|
|Extensor digiti indicis||Extension of the index finger||Posterior interosseous (radial)||C7–C8|
|Extensor carpi ulnaris||Extension of the wrist||Posterior interosseous (radial)||C7–C8|
|Mobile wad||Brachioradialis||Elbow flexion||Radial||C5–C6, (C7)|
|ECRL||Extension of the wrist||Radial||C6–C7|
|ECRB||Extension of the wrist||Posterior interosseous (radial)||C7–C8|
Table 6-2 Muscles of the Elbow and Forearm: Their Actions, Nerve Supply, and Nerve Root Derivation |Favorite Table|Download (.pdf)
Table 6-2 Muscles of the Elbow and Forearm: Their Actions, Nerve Supply, and Nerve Root Derivation
|Action||Muscles Acting||Peripheral Nerve Supply||Nerve Root Deviation|
- Biceps brachii
- Pronator teres
- Flexor carpi ulnaris
- C5–C6, (C7)
- C5–C6, (C7)
- Posterior interosseous (radial)