Learning Objectives
By the end of this section, you should be able to:
- Describe the articulations and joint types of the elbow.
- Identify the stabilising structures of the elbow joint.
- Outline the blood supply and innervation of the joint.
- Explain the movements permitted at the elbow.
- Recognise common clinical conditions affecting the elbow.
The elbow joint connects the upper arm to the forearm. It is a hinge-type synovial joint, primarily allowing flexion and extension of the forearm.
In this article, we will review the anatomy of the elbow joint, including its articulations, stabilising structures, movements, and important clinical correlations.
Structures of the Elbow Joint
Articulating Surfaces
The elbow joint consists of two articulations within a single joint capsule:
- Trochlear notch of the ulna ↔ trochlea of the humerus
- Head of the radius ↔ capitulum of the humerus
Note: The proximal radioulnar joint shares the same capsule as the elbow but is usually described separately, as it permits pronation and supination, not flexion and extension.
Joint Capsule and Bursae
The joint capsule is strong and fibrous, enclosing the elbow joint and providing stability while allowing movement. It is thickened medially and laterally to form the collateral ligaments.
Bursae of the Elbow
A bursa is a small sac containing synovial fluid that reduces friction between moving structures. The elbow has three important bursae:
- Intratendinous olecranon bursa – within the triceps tendon
- Subtendinous olecranon bursa – between the olecranon and triceps tendon
- Subcutaneous olecranon bursa – between the olecranon and skin
- Inflammation here causes olecranon bursitis
Ligaments
The joint capsule is reinforced by two main collateral ligaments:
- Radial collateral ligament – from the lateral epicondyle; blends with the annular ligament of the radius
- Ulnar collateral ligament – from the medial epicondyle to the coronoid process and olecranon
Blood Supply
The elbow receives a rich arterial anastomosis from branches of the:
- Brachial artery
- Radial artery
- Ulnar artery
Innervation
The joint is innervated by branches of:
- Musculocutaneous nerve
- Radial nerve
- Ulnar nerve
- Median nerve
Movements
The elbow functions as a hinge joint, allowing:
| Movement | Main Muscles |
|---|---|
| Flexion | Brachialis, biceps brachii, brachioradialis |
| Extension | Triceps brachii, anconeus |
Clinical Relevance
1. Bursitis
Inflammation of a bursa leads to pain and swelling.
The most common type is subcutaneous olecranon bursitis, often caused by repeated pressure or trauma (e.g., leaning on hard surfaces). Because it lies just beneath the skin, it may become infected after a minor injury.
2. Elbow Dislocation
Usually occurs after a fall on the hand with the elbow flexed. The distal humerus is driven through the anterior capsule, tearing the ulnar collateral ligament. The ulnar nerve may also be affected.
- Most dislocations are posterior
- Dislocations are named by the position of the ulna and radius, not the humerus
3. Epicondylitis
Overuse of forearm tendons causes pain at the epicondyles:
- Tennis elbow (lateral epicondylitis) – extensor tendon overuse
- Golfer’s elbow (medial epicondylitis) – flexor tendon overuse
Mnemonic:
- Golf → middle → medial
- Tennis → lateral line → lateral
4. Supracondylar Fracture
Common in children after a fall on an outstretched hand with the elbow extended. The fracture passes between the epicondyles and may damage:
- Brachial artery → forearm ischaemia → Volkmann’s contracture
- Median, ulnar, or radial nerves
Key point: Always perform and document a full neurovascular examination. A pale, pulseless limb requires urgent surgical intervention.
