Radial abduction

The Radial abduction is a bending movement of the hand or finger in the direction of the spoke, as it is performed in the proximal wrist by five hand muscles. The range for movement to the thumb side is up to 20 degrees. Radial abduction can be disturbed in muscle diseases.

What is radial abduction?

The movable connection between several bony skeletal elements is also known as a joint. Due to the joints, the human body parts and extremities have a wide range of motion with different forms and directions of motion.

The term anteversion means, for example, movements in the sagittal plane. The extension summarizes all active and passive stretching movements in a particular joint that straighten the associated body part. Flexion, on the other hand, describes the active and passive flexion movements in a joint.

With adduction, a part of the body is in turn brought to the center of the body or the longitudinal axis of the extremity and applied in this way. The opposite of this is abduction. This form of movement corresponds to a lateral continuation or spreading of body parts, which starts from the center of the body or the longitudinal axis. Abduction typically takes place in the frontal plane.

The radial abduction is therefore a removal of the fingers or hand in the direction of the radius. The term radius refers to the forearm bone, the spoke. This is a long bone at the end of the upper arm, which extends to the wrist. If the abduction is in the direction of the ulna, it is called an ulnar abduction.

Function & task

The radial abduction takes place in the carpal joint. As such, the distal and proximal wrist are combined. The proximal carpal joint is the articulated connection between the distal end of the spoke (facies articularis carpi radialis) and the three proximal carpal bones (ossa carpalia). The proximal carpal bones are the scaphoid bone (os scaphoideum), the moon bone (os lunatum) and the triangular bone (os triquetrum).

The intervertebral disc of the spoke-ulnar joint is involved in the formation of this carpal joint. The joint capsule of this joint is stabilized by radiating ligaments. From a functional point of view, the joint is an ellipsoid joint (Articulatio ellipsoidea) with two different degrees of freedom. In addition to flexing towards the palm and stretching towards the back of the hand, it can perform splaying movements towards the ulna and radius.

The flexion is up to 80 degrees and the dorsiflexion towards the back of the hand is up to 70 degrees. The spreading movements in this joint have a radius of around 20 degrees towards the spoke. The ulnar abduction towards the ulna is even up to 40 degrees. The distal carpal joint is significantly more restricted in its movements. As a result, the proximal carpal joint is particularly instrumental in the mobility of the hand and fingers.

Radial abduction in the proximal wrist is performed by various muscles. The most important of these muscles involved are the extensor carpi radialis longus, the abductor pollicis longus, and the extensor pollicis longus. However, the flexor pollicis longus muscle and the flexor carpi radialis muscle also play an important role in the radial abduction of the hand or fingers. The flexor pollicis longus muscle and the flexor carpi radialis muscle are so-called flexors. The extensor carpi radialis longus muscle, the abductor pollicis longus muscle and the extensor pollicis longus muscle, on the other hand, are known as extensors of the hand. Another name for extensor muscles is the term extensor. Flexors are also called flexors.

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Illnesses & ailments

The radial abduction of the hand or fingers can be restricted by a disease of the realizing muscles, cause pain or generally no longer possible. Muscle diseases, for example, can have inflammatory causes. In this context, tendonitis should be mentioned, which can cause severe pain. Tendonitis can occur, for example, as a result of overloading and may also affect the radial abduction of the hand in the muscles mentioned.

Arthrosis in the proximal carpal joint can also limit radial abduction. In osteoarthritis, the cartilage in the joint is broken down piece by piece. This phenomenon is often the result of a misalignment. However, overloads are also conceivable in this context. In the beginning, osteoarthritis pain is load-dependent. In the later process, permanent pain sets in, which can also be felt when the patient is resting. When the cartilage has been worn away, the joint surfaces rub against each other without protection and wear each other off in this way.

Carpal tunnel syndrome can also cause pain and restricted mobility in the proximal wrist. In this disease, compression of the carpal tunnel occurs along the median nerve. It is an anatomical structure made of bones and ligaments. The nerve irritation in this structure typically causes paresthesia and pain. Restrictions in mobility in the affected supply area only occur later.

Compression of the ulnar nerve near the wrist can also cause pain, sensory disturbances and loss of movement. This clinical picture is also known as Loge de Guyon syndrome and can later lead to atrophy of the fingers and hand muscles. Long-term, everyday compressions of the nerve are one of the most important causes of the phenomenon.

Tumors can also dent the nerve under certain circumstances. Loss of movement of the hand is caused by polyneuropathies or central nervous diseases much less frequently.