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Structure

Elbow joint

Not medically reviewed · Content last updated · 1 min read ·

This is the date the draft was written, not a medical review date.

The elbow is a compound synovial joint sharing one capsule among three articulations: humero-ulnar (hinge), humeroradial and proximal radio-ulnar (pivot). It allows flexion and extension, and with the radio-ulnar joints, pronation and supination.

Terminologia Anatomica (Latin): Articulatio cubiti · Open in the 3D atlas

Location

It lies between the arm and forearm; the cubital fossa in front contains the biceps tendon, brachial artery and median nerve, while the ulnar nerve runs in the groove behind the medial epicondyle.

Structure

The trochlea articulates with the trochlear notch of the ulna and the capitulum with the radial head. The capsule is reinforced by the ulnar (medial) collateral and radial (lateral) collateral ligaments; the annular ligament holds the radial head against the ulna.

Blood supply

The arterial anastomosis around the elbow is formed by the collateral branches of the brachial and profunda brachii arteries and the recurrent branches of the radial, ulnar and interosseous arteries.

Innervation

The capsule is supplied by branches of the musculocutaneous, radial, ulnar and median nerves (Hilton law: nerves to muscles crossing a joint also supply the joint).

Function

Flexion by brachialis, biceps and brachioradialis; extension by triceps (and anconeus). Pronation and supination, mainly by pronator teres/quadratus and by biceps/supinator, occur at the radio-ulnar joints.

Clinical correlations

Posterior dislocation is the usual pattern, with possible ulnar nerve or brachial artery injury. Supracondylar fractures in children threaten the brachial artery and anterior interosseous nerve. Lateral epicondylitis (tennis elbow), medial epicondylitis (golfer elbow), olecranon bursitis and pulled elbow (radial head subluxation in young children) are common.

Common exam points

  • Three articulations in one capsule: humero-ulnar, humeroradial, proximal radio-ulnar.
  • Cubital fossa contents (lateral to medial): biceps tendon, brachial artery, median nerve.
  • Ulnar nerve behind the medial epicondyle; vulnerable to medial epicondyle fractures.
  • Collateral ligaments: ulnar (medial) and radial (lateral); annular ligament around the radial head.
  • Radial head subluxation (pulled elbow) occurs in young children after traction on the arm.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Netter FH. Atlas of Human Anatomy. Elsevier — Tier 3 (textbook)

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