Parts of the Elbow Joint
The elbow joint consists of 3 separate articulations enclosed in a single capsule:
|Humeroulnar joint||Simple hinge-joint|
|Humeroradial joint||Limited ball-and-socket joint||Limited pronation-supination in semiflexion|
|Proximal radioulnar joint||Pivot joint||Pronation-supination in any degree of flexion-extension|
Ligaments of the Elbow Joint
The elbow capsule is supported by the ligaments of the elbow, especially the radial (lateral) and ulnar (medial) collateral ligaments.
|Radial collateral ligament||Stabilizes the elbow joint against varus stress|
|Ulnar collateral ligament||Stabilizes the humeroulnar joint against valgus stress|
|Annular ligament of the radius||Anterior-posterior margins of the radial notch||Surrounds and anchors the radial head to the radial notch of the ulna|
|Interosseous membrane||Interosseous margins of the radius and the ulna|
Functional Anatomy and Movements of the Elbow Joint
The functional anatomy of the elbow is unique secondary to the orientation and multiple articulations. The main function of the elbow is to link the shoulder and the hand and position and stabilize the hand during activities.
- Normal valgus carrying angle: 5–15 degrees
- Prevents arm from contacting hips
- Women > men, greater in dominant limb (both sexes)
Muscles of the Elbow Joint
The muscles of the elbow originate in the upper arm and insert into the forearm, producing flexion-extension of the elbow as well as supination-pronation of the forearm. The muscles also provide dynamic stabilization to the elbow joint.
|Brachialis muscle||Anterior aspect of the humerus lateral to the deltoid tuberosity||Ulnar tuberosity||Musculocutaneous nerve (C5–C7)||Flexes the elbow and assists with supination|
|Brachioradialis muscle||Proximal 2 thirds of lateral supracondylar ridge||Lateral surface of distal radius and pre-styloid process||Radial nerve (C6)||Weak flexor of the elbow, strong flexor when forearm mid-pronated|
|Biceps brachii muscle||Short head: coracoid process; long head: supraglenoid tubercle||Tuberosity of the radius||Musculocutaneous nerve (C5–C6)||Supinates the forearm and assists with elbow flexion|
|Triceps brachii||Long head: infraglenoid tubercle; lateral and medial heads: posterior humerus||Olecranon||Radial nerve (C6–C8)||Extends the elbow|
|Anconeus||Inserts on the posterior aspect of lateral epicondyle||Lateral surface of the olecranon||Radial nerve (C7, C8)||Assists in extension of the elbow and stabilizes the joint|
Neurovascular and Lymphatic Supply of the Elbow
- Anteriorly: The musculocutaneous, median, and radial nerves pass anterior to the elbow and innervate the anterior capsule.
- Posteriorly: The ulnar nerve passes posteriorly and medially at the elbow and innervates the posterior capsule.
- Brachial artery
- Courses down the anterior surface of the arm into the cubital fossa
- Bifurcates into the radial and ulnar artery in the proximal forearm
- The cubital anastomosis is an extensive circulatory system surrounding the elbow, formed from branches of the brachial, radial, and ulnar arteries.
- Basilic and cephalic vein: the primary superficial veins of the upper arm
- Connected at the elbow anteriorly by the median cubital vein
Epitrochlear or cubital lymph nodes are found at the elbow and drain proximally to the axillary lymph nodes.
The following are common conditions related to the elbow:
- Humerus fracture: A distal humerus fracture primarily occurs from falling on the outstretched arm. Humerus fractures are classified into supra-, trans-, or intercondylar fractures. Depending on the location and the extent of the fractures, these injuries may need to be reduced and addressed surgically.
- Supracondylar fracture: a common traumatic fracture in children that occurs from a fall on an outstretched arm or hand. Treatment often includes closed reduction and percutaneous pinning, which may be urgent if the neurovascular system is compromised.
- Olecranon fracture: occurs secondary to falling on the flexed arm. Depending on the complexity of the fracture, the fracture may be treated surgically with a tension band osteosynthesis.
- Radial head fracture: One of the most common fractures in adults; occurs secondary to falling on the extended arm. Can occur with or without dislocation and may include multiple fragments. May require surgical management.
- Elbow dislocation: 2nd-most common joint dislocation after the shoulder. A fall on an outstretched hand is the usual mode of injury. Complex elbow dislocations have an associated fracture or neurovascular injury.
- Nursemaid’s elbow (radial head subluxation): also called “babysitter’s elbow.” Common injury of young children that occurs secondary to longitudinal traction on the hand and forearm. Causes a subluxation of the annular ligament from the normal location surrounding the radial head. Treatment is usually closed reduction using a supination technique.
- Medial/lateral epicondylitis or flexor/extensor tendinosis: a common problem of the elbow, with localized pain at either the lateral (extensor) or medial (flexor) epicondyle. Associated with inflammation or degeneration of the tendons of the area due to repetitive microtrauma/overuse. Medial epicondylitis or flexor tendinosis is also known as “golfer’s elbow,” while lateral epicondylitis or extensor tendinosis is known as “tennis elbow.”
- Ulnar nerve compression syndrome: also called cubital tunnel syndrome. Usually due to a direct trauma of the ulnar nerve or repetitive/prolonged elbow flexion. Less commonly secondary to hypermobility of the ulnar nerve or osteophytes in the cubital tunnel.
- Drake, R.L., Vogl, A.W., & Mitchell, A.W.M. (2014). Gray’s Anatomy for Students (3rd ed.). Philadelphia, PA: Churchill Livingstone.