What is the abduction?Abduction is the opposite of adduction and means the lateral contraction of limbs or hand and foot members.
In abduction, a body part is moved laterally from the body. It is thus spread from the body center or extremities of the longitudinal axis of the respective limb. The executive level of the abduction movement is also called the frontal plane.
The opposite of abduction is the so-called adduction, which also takes place on the frontal level, but continues in the opposite direction. A part of the body is thus introduced laterally to the middle of the body or the longitudinal axis of extremities during the adduction than in the case of abduction. This movement is also called mooring.
The two opposing movements are performed by different muscles. The abducting muscles are called abductors. Those for adduction are analogously referred to as adductors. The innervation of both muscle types occurs through peripheral motor nerves, which receive their commands from the central nervous system. Like adduction, abduction can also take place in the context of voluntary motor skills as well as involuntary reflex motor skills.
Function & Task
The mobility of the human limbs is outstanding and includes movement directions such as abduction and adduction. In addition to the legs, human toes, arms, hands, toes and thumbs are capable of abduction in the sense of a spreading movement.
For example, the hand knows two different types of abduction: radial abduction and ulnar abduction. In ulnar abduction, the hand or fingers move in the direction of the elbow. So they are bent to the little finger side. The carpal joint is moved by various muscles, especially the extensor carpi ulnaris, the flexor carpi ulnaris and the extensor digiti minimi. Radial abduction the opposite direction. The fingers or the hand do not move in the direction of the spine but in the direction of the spokes. So they are bent to the thumb side. In addition to the carpal joint, this abduction movement involves the muscles extensor carpi radialis longus, the abductor pollicis longus, the extensor pollicis longus, the flexor pollicis longus, and the flexor carpi radialis muscles.
Abductions are correspondingly complex movements and result from an ideal interaction of different muscles, tendons and joints. In order to initiate the movements and thus to move the relevant joint, the muscular abductors contract.
Abductions are crucial for various movements and activities of everyday life. As you walk, abduction from one leg, for example, takes you one step to the side. Even if the arm has to be lifted out, abduction is needed. The same applies to the spreading movements of the fingers.
Abduction usually takes place actively, but can also be initiated passively during investigations. For example, the doctor can check the mobility of certain limbs, even if the patient can not actively move them. The abduction is given in degrees. Depending on the limb, different ranges are considered physiological.
Diseases & complaints
If a limb abduction is no longer possible, only limited or only possible in pain, this has either muscular or neuronal causes. Sometimes, more difficult abduction is also associated with joint conditions such as osteoarthritis, which cause pain during exercise. Stiffening of joints or muscles can in turn completely prevent abduction. The same applies to muscle fiber tears or tendon tears.
The neuronal causes of difficult abduction are wide-ranging. For example, polyneuropathies of the peripheral nervous system can be considered, as they can be due to malnutrition, various infections or poisoning.
In polyneuropathies, the nerves of the peripheral nervous system are no longer conductive enough to initiate certain movements. However, the problem can also be in the central or motor nervous system. In the brain and spinal cord lie the so-called motor neurons. They are the central switching point for voluntary motor skills, so that their damage can lead to various signs of paralysis.
In direct contact with the motor neurons are the efferent pyramidal tracts that pass through the spinal cord and connect the first to the second motor neuron. When the pyramidal tracts are damaged, movement impulses from the central nervous system no longer reach the second motoneuron and can not be transmitted from the control center to the skeletal muscles. In consequence, the abduction can be completely absent.
Lesions of the central motoneurons or the pyramidal tract may occur in the context of various neurological diseases. In addition to inflammatory diseases such as multiple sclerosis, strokes, hypoxia or degenerative diseases such as ALS can cause discomfort in the motor system and thus in the abduction.
If the abduction of a particular part of the body is limited, the physician will check the motor deficit and indicate the remaining range of the abduction. In the course of therapy, this process is repeated regularly to assess the success of the treatment or possible worsening of the symptoms.