major bones of the elbow

Daniel Parker

2 min read

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16-03-2025

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The elbow joint, a vital connection point between the upper arm and forearm, is a complex structure composed of three major bones: the humerus, ulna, and radius. Understanding the anatomy of these bones is crucial for comprehending elbow function and diagnosing related injuries. This article will delve into the structure and function of each bone, highlighting their roles in elbow movement and stability.

The Humerus: The Upper Arm Bone

The humerus is the long bone of the upper arm. Its distal end, the part closest to the elbow, plays a critical role in forming the elbow joint. This distal end features:

• Capitulum: A rounded knob-like structure that articulates with the head of the radius. This joint allows for rotation of the forearm.
• Trochlea: A pulley-shaped structure that articulates with the trochlear notch of the ulna. This joint primarily allows for flexion and extension of the elbow.
• Medial and Lateral Epicondyles: These bony projections on either side of the distal humerus serve as attachment points for important muscles of the forearm. Many elbow injuries involve these epicondyles.

The Ulna: The Medial Forearm Bone

The ulna is the larger of the two forearm bones, located on the medial (pinky finger) side. Its proximal end, the part closest to the elbow, is key to elbow articulation. This end contains:

• Trochlear Notch: A concave, curved surface that articulates with the trochlea of the humerus. This creates the hinge-like action that allows for elbow flexion and extension.
• Olecranon Process: This prominent projection forms the bony point of the elbow. It fits into the olecranon fossa of the humerus, preventing hyperextension of the elbow.
• Coronoid Process: Located anterior to the olecranon process, this process also contributes to the stability of the elbow joint.

The Radius: The Lateral Forearm Bone

The radius is the smaller of the two forearm bones, positioned laterally (thumb side). Its proximal end articulates with both the humerus and the ulna. Key features include:

• Head: A disc-shaped structure that articulates with the capitulum of the humerus. This allows for pronation and supination (rotation) of the forearm.
• Radial Neck: The narrow portion connecting the head to the shaft of the radius. Fractures frequently occur in this area.
• Radial Tuberosity: A roughened area on the medial aspect of the radial shaft. This serves as an attachment point for the biceps brachii muscle.

How the Bones Work Together

The three bones of the elbow work in concert to provide a remarkably versatile joint. The humerus acts as a stable base, while the ulna and radius allow for flexion/extension and pronation/supination. The intricate interlocking of these bones, along with strong ligaments and muscles, creates a stable and highly mobile joint.

Common Elbow Injuries

Understanding the bones of the elbow helps in understanding common injuries such as:

• Fractures: Fractures of the humerus, radius, or ulna are common, especially in falls or high-impact trauma. Location and severity vary greatly.
• Dislocations: The elbow joint is prone to dislocation, often involving displacement of the radius and ulna from the humerus.
• Epicondylitis: Inflammation of the tendons attached to the medial (golfer's elbow) or lateral (tennis elbow) epicondyles of the humerus.
• Osteoarthritis: Degenerative joint disease affecting the articular cartilage of the elbow joint, leading to pain and reduced mobility.

Note: This article provides a general overview. For specific medical concerns, always consult a qualified healthcare professional. They can provide a proper diagnosis and treatment plan.