The term palmar flexion is used on the human body exclusively for a movement of the hand. It is involved in many everyday and athletic movements.
What is palmar flexion?
Palmar flexion is a flexion that is in the direction of the palm. It involves the palm of the hand approaching the forearm. Like its countermovement, dorsiflexion, palmar flexion is a movement that occurs in the wrist. The term ‘flexion’ (‘bending’), otherwise commonly used in other joints, is given a directional suffix in this case. Palmar is derived from the anatomical term ‘palma manus’ (‘palm’). Accordingly, palmar flexion is a flexion that runs in the direction of the palm. The palm approaches the forearm in the process. The movement takes place in the wrist as the proximal carpal row rotates as a convex joint partner in the socket of the radius about an imaginary axis of motion that runs transversely through the joint. The amplitudes of motion of palmar flexion and dorsiflexion are approximately equal but depend on the position of the fingers. When the middle and end joints are extended, palmar flexion normally reaches 85°. With flexion, it is about 20° – 30° less. This is due to the fact that the finger extensors, whose tendons run along the back of the hand and fingers, have almost exhausted their extension possibilities due to flexion and limit further movement.
Function and task
Finger position also plays an important role in the many activities in daily life and sports in which palmar flexion is involved. The force development that occurs from palmar flexion alone is significantly less with flexed fingers than with extended fingers. In impact sports such as tennis, squash and badminton, racket position and technical execution are important for this reason. In forehand and smash strokes, when executed correctly, power is generated from the combination of palmar flexion and supination (outward rotation) or pronation (inward rotation). In smash strokes or indications in volleyball, the finger joints are extended and full power development is achieved via explosive folding of the hand. This is the main component of the acceleration of the ball, other movements have only an additional function. The same circumstance can also be illustrated in everyday activities. especially when grasping, holding and transporting objects. Whenever a relatively large amount of force is needed to hold on to something, the so-called functional position of the hand is used. While the fingers are closed tightly around the object, the wrist is set in a slight dorsiflexion, as this makes the efficiency of the finger flexors more powerful. The situation is different when light objects, for example when eating, are picked up and brought to the mouth. Here, palmar flexion is used as an important component because it brings the hand closer to the object and the mouth. The functional position of the hand with the slight dorsiflexion can be broken by conscious processes. A typical activity in which this occurs is the uppercut in boxing. The momentum coming from the shoulder and elbow joints is transferred to the opponent through the wrist, fixed in palmar flexion, without much loss of power.
Diseases and complaints
Injuries that can negatively affect palmar flexion include all fractures in this area. The distal radius fracture is the most significant and affects all movements of the wrist. Usually, this trauma is treated surgically or conservatively, which in both cases is accompanied by temporary immobilization. As a result, movement restrictions and muscle atrophy set in, significantly impairing hand function. Although the negative effects on dorsiflexion are greater, palmar flexion functions are also affected. Tendinitis is a typical overuse syndrome that often affects people who perform monotonous movements or holding work of the forearm muscles for long periods of time. The finger extensors and flexors are affected, with their long tendons running from the forearm through the wrist to the end phalanges of the fingers. The leading symptom is acute pain during use and stretching of the affected muscles with a reactive sparing behavior.If the extensors of the fingers are affected, palmar flexion is also impaired in addition to finger flexion. Active palmar flexion may be reduced or completely absent if the nerve structures supplying it are damaged. In that case, this is the median nerve. Injuries in the area of the upper arm or near the elbow can lead to such a nerve lesion. Conversely, the so-called drop hand, which occurs as a result of damage to the [[radial nerve[[, is characterized by the fact that the hand cannot be actively brought out of palmar flexion. All other neurological conditions and traumas in which flaccid paralysis of the arm and hand muscles may occur also affect the palmar flexors. These conditions include spinal cord injuries at the level of the cervical spine as well as polyneuropathy. Stroke often has just the opposite consequences. The spastic pattern of the hand that often develops has the combination of palmar flexion, pronation, and flexion of all finger joints as components. With severe hypertonus, affected individuals are unable to open the hand and extend and raise the arm. Massive, irreversible contractures develop. An autoimmune disease that preferentially affects the hand and fingers in the early stages is chronic polyarthritis (rheumatoid arthritis). This progressive disease directly attacks the joints, which are increasingly destroyed. The subsequent degradation and remodeling processes lead to impairment of all movements of the hand and fingers. Both overmovement and stiffening can occur in the joints.
