The elbow joint is a complex and essential part of the upper limb that allows for a wide range of movements. Located at the junction between the arm and the hand, the elbow joint is a synovial joint that allows for flexion and extension, pronation and supination. In this article, we'll take a closer look at the anatomy, functions, and clinical considerations of the elbow joint.
Types of Synovial Joints in the Elbow
There are three main types of synovial joints in the elbow:
- Humeroulnar hinge joint: This variety of the elbow joint is a hinge joint that allows for flexion and extension.
- Humero-radial ball and socket joint: This variety of the elbow joint is a ball and socket joint that allows for flexion and extension.
- Proximal radio-ulnar pivot joint: This variety of the elbow joint is a pivot joint that allows for pronation and supination.
Articulating Surfaces of the Elbow Joint
The articulating surfaces of the elbow joint include:
Joint Capsule and Synovial Membrane
The elbow joint is covered by a joint capsule that encloses all three articulations. The capsule is thinned out anteriorly and posteriorly and thickened medially and laterally. It is attached to the coronoid and radial fossa anteriorly and the olecranon fossa posteriorly. The synovial membrane lines the capsule and bulges downwards to the neck of the radius in the lower end of the annular ligament.
Ligaments Supporting the Elbow Joint
The elbow joint is supported by several ligaments, including the lateral ligament, which attaches to the annular ligament distally. The annular ligament is funnel shaped in adults, but has vertical sides in children.
Blood and Nerve Supply to the Elbow Joint
The blood supply to the elbow joint comes from the elbow anastomosis, which is made up of branches of the brachial, radial, and ulnar arteries. The nerve supply to the elbow joint comes from the ulnar, median, radial, and musculocutaneous nerves.
Muscles Controlling Elbow Joint Movement
The movements of the elbow joint are controlled by several muscles, including the flexors (biceps, brachioradialis, and forearm flexor muscles) and extensors (triceps). The joint is also able to pronate and supinate thanks to the pronator teres and flexor carpi radialis muscles, as well as the biceps, supinator, extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus. Supination is generally more powerful than pronation.
Clinical Considerations
There are several clinical considerations to keep in mind when it comes to the elbow joint. These include epicondylitis (also known as tennis elbow and golf elbow), pulled elbow, posterior dislocation of the elbow, miner's elbow (also known as student's elbow or olecranon bursitis), and the carrying angle.
Epicondylitis
Epicondylitis is an inflammation of the common extensor origin (tennis elbow) or common flexor origin (golf elbow). Pulled elbow, also known as subluxation of the head of the radius,
Carrying angle
The carrying angle is the angle formed by the extended forearm and the arm. In a normal adult, the carrying angle is about 150 degrees, but it is generally more in females. The carrying angle is created by the transverse axis of the elbow joint, which is directed medially and downwards. The carrying angle disappears when the elbow is fully flexed and the forearm is pronated.
An increased carrying angle, also known as cubital valgus, may be an indication of Turner syndrome, a fracture, or other trauma. A decreased carrying angle, also known as cubital varus, is less common.
Overall, the carrying angle is an important aspect of elbow joint anatomy and can be affected by various conditions and injuries. It is important for healthcare professionals to consider the carrying angle in their diagnosis and treatment of elbow joint issues.
Pulled Elbow
Pulled elbow, also known as subluxation of the head of the radius, is a common injury in young children. It occurs when the head of the radius slips out of the annular ligament due to a sudden jerk of the arm or a sudden pull in pronation. This results in a partial dislocation of the elbow joint, with the head of the radius still in contact but not fully aligned with the rest of the joint.
Pulled elbow is caused by the head of the radius being small or undeveloped in young children. It can be caused by a variety of factors, including falls, sports injuries, or sudden movements.
Posterior Dislocation
Posterior dislocation of the elbow is a rare but serious injury that occurs when the elbow joint becomes dislocated, resulting in a loss of the equilateral triangular relationship between the two epicondyles of the humerus and the olecranon process. This type of dislocation is caused by a traumatic force applied to the elbow, such as a fall or a sports injury.
Symptoms of posterior dislocation of the elbow may include severe pain, swelling, bruising, difficulty moving the elbow, numbness or tingling in the hand, and a deformity of the elbow. It is important to seek medical attention immediately if you suspect a posterior dislocation of the elbow.
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Elbow Joint Anatomy
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