The elbow is an important joint in the arm that connects the upper arm to the forearm. The elbow joint consists of several sub-joints and allows for a wide range of movements. In anatomy, the humerus, ulna, and radius play a central role. The joint is stabilized by muscles, ligaments, and a joint capsule. Movements such as flexion, extension, and rotation of the forearm are possible here. The two forearm bones, in particular, work closely together to ensure precise movement. Diseases or injuries of the elbow can significantly impair its function.
The Upper Arm
The humerus is the longest bone in the arm. With its rounded head (humeral head), it forms part of the shoulder joint. The olecranon processes, which extend from the lower end of the humeral shaft, are located lateral to the elbow joint.
The muscles of the upper arm can be divided into two groups: the flexors and the extensors. The most important upper arm muscles are the forearm flexors (biceps brachii and brachialis) at the front and the forearm extensor (triceps brachii) at the back.
The Forearm
The forearm is located between the elbow joint and the carpal bones and consists of two bones: the radius and the ulna. The radius is connected to the carpal bones via the two highly mobile wrist joints. It is primarily the muscles originating in the forearm that control the movements of the hand. Only the slender tendons of these muscles are located directly within the hand.
The Elbow
The elbow (cubitus), the junction of the upper and lower arm, consists of the elbow crease (elbow fossa, fossa cubitalis) and the elbow joint (articulatio cubiti). In the elbow joint, the humerus, radius, and ulna form three sub-joints that are enclosed by a common joint capsule. This capsule is reinforced by three ligaments (medial ligament, lateral ligament, and annular ligament).
Elbow pain—tennis elbow, problems with the flexors or humerus, or disorders of the elbow joint
Disorders and injuries of the upper arm, forearm, and elbow
Fractures in the forearm region are common. A distinction must be made between an isolated fracture of the radius (radius fracture—the most common fracture of all), the ulna (ulna fracture—rare), and a complete forearm fracture, in which both forearm bones are affected (not quite as common as the radius fracture).
Fractures of the upper arm include a fracture of the humeral head (humeral head fracture), the rarer humeral shaft fracture, and a fracture in the lower part of the upper arm.
In the elbow region, injuries can include elbow fractures, elbow bursitis, dislocations of the elbow joint, and Chassaignac’s paralysis (subluxation of the radial head). The radial head slipping out of the annulus is common in children, for example, when an adult suddenly pulls up a child’s outstretched arm to catch them as they stumble. However, the radial head can usually be easily reduced.
Tendinitis occurs most frequently in the wrist area. A biceps tendon tear (biceps tendon rupture) does not always cause severe pain.
Conclusion
Overall, the elbow and forearm form a functional unit in which the elbow joint connects the humerus to the bones of the forearm. The anatomy of the elbow shows that three bones—namely, the ulna, the radius, and the humerus—work together and, as the Articulatio cubiti, consist of three partial joints. The structure of the elbow allows for flexion and extension as well as pronation and supination, resulting in a complex rotational movement.
In this process, the radius performs a rotational movement around the ulna, allowing the hand to move flexibly. This movement enables the palm to be turned downward or the arm to be extended and flexed. The ligaments of the elbow joint and the joint capsule stabilize the two bones, while blood supply and innervation ensure proper function.
The inner side of the elbow, particularly in the area of the sulcus nervi ulnaris, is sensitive and can cause discomfort when pressure is applied. Elbow pain is often caused by painful inflammation or by conditions and injuries such as epicondylitis. An elbow injury resulting from a fall onto an outstretched arm can also lead to a fracture, dislocation, or subluxation.
Typical examples include elbow dislocations or problems with the head of the radius, which can limit the mobility of the hand. Elbow extension, as well as flexion and extension, are essential for everyday movements, and the back of the upper arm plays an important role in this. Overall, it is clear that the elbow joint is one of the most complex joints, as it must enable finely coordinated movements both internally and externally while simultaneously providing stability.
FAQ
What is the elbow joint?
The elbow joint is a joint that connects the upper arm to the forearm. It consists of three sub-joints and enables complex movements of the arm.
Which bones make up the elbow?
The elbow consists of the humerus, the ulna, and the radius. Together, these three bones form the elbow joint.
What movements are possible at the elbow?
The elbow allows for flexion and extension, as well as pronation and supination of the forearm. This enables the hand to be rotated and moved.
What are common elbow conditions?
The most common conditions include tennis elbow and golfer’s elbow. These are caused by overuse and lead to painful inflammation.
What happens when the elbow is injured?
An elbow injury can result in fractures, dislocations, or ligament injuries. This can severely limit the mobility and function of the arm.