Rotational motion occurs as a movement on the human body, including the foot and forearm. It plays a significant role in walking and in important daily activities of the hand.
What is the rotary motion?
Rotational motion occurs as a movement on the human body at the foot and forearm, among other places. In the foot, the motion occurs in the anterior chamber of the lower ankle joint, which is formed by three tarsal bones. One of the three, the os naviculare rotates around the other two during this movement, so that the inner edge of the foot is rotated upwards. This process is purely descriptive. A pure rotation cannot be actively performed in this joint, because the executing muscles are not able to do so due to their course. Therefore, other movement components are always coupled to the rotational movement. Isolated rotation can be performed passively by fixation of the two tarsal bones close to the body, for example during motion studies. The rotational motion at the upper extremity is a motion between the two forearm bones. The radius rotates around the ulna so that the two bones are parallel in the final position. During the opposite motion, pronation, a strong crossover occurs. Due to the coupling of the wrist and the carpal bones, the rotation of the forearm bones carries the hand along. During rotation, the palm increasingly points toward the body; during pronation, the back of the hand points toward the body.
Function and task
Rotation at the foot is involved in all free movements that are directed inward. It is an important component of the swing leg phase. The stronger the orientation to the center of the body and the faster the execution, the greater its importance. In many sports activities, such activities occur. A typical example is the movements in martial arts, where the aim is to get the opponent off his feet with a leg swing or a diagonal kick. In soccer, a pass or cross with the instep is very much characterized by the rotation and power development of the executing muscles, the supinators. The spin that the ball gets is mainly a transfer of the energy of the supinator foot position to the ball movement. All activities of the hand directed towards the body, which take place in the upper and front area, are functionally possible only through the involvement of the rotational movement. Its interaction with adduction and flexion in the shoulder joint and flexion in the elbow allow the hand to reach almost any point of the head and upper trunk. Perhaps the most important activity performed this way is eating. But other actions in the daily routine, such as washing hair, blowing nose, scratching the head or neck, as well as picking up objects and pulling them towards the body, are also characterized by these movement components. In sports, movements of the arms that are performed from the bottom outside to the top inside are often associated with a rotation. Characteristic movement sequences with these components are the forehand strokes of the racket sports tennis, squash and badminton. In badminton in particular, the rotation provides the decisive movement impulse for accelerating the ball. The same trajectory with a strong supination component of the hand can also be observed in boxing when uppercuts are hit. The biceps, as the flexor and strongest supinator, is used to its full strength. All lunging movements of the arm and hand above the head involve rotation as a pre-extension component for the following hitting or throwing motion, such as throwing a stone or smashing in volleyball.
Diseases and ailments
As with all movements, rotation can be affected by a decrease in muscle activity or other processes that limit the amplitude of movement. The impact on vital functions such as eating and walking is often striking. Affected individuals can no longer fully perform these movements, if at all, and thus lose their independence. In addition to systemic diseases such as muscular dystrophies or amyotrophic lateral sclerosis, it is often specific injuries and conditions that hinder functions. In the foot, these can be fractures in the tarsal bones or ligament injuries. They often occur as a result of awkward movements due to the action of external forces.A typical mechanism of injury is the so-called supination trauma, in which the foot twists inward, often resulting in bone fractures and tears of the external ligaments. Herniated discs or peripheral nerve lesions can lead to a condition called foot jack weakness. Rotation is affected when the tibial nerve is damaged. A special form of impairment of movement in the foot typically develops as a result of a stroke. Hemiplegia develops on the affected side with spasticity of the leg with a strong tendency to extend and supinate. When walking, the leg is very strongly guided inward via a circular movement in the hip joint and the foot cannot be placed properly. This results in the so-called Wernicke-Mann gait pattern. In the upper extremity, damage to arm nerves can negatively influence the functions in the hand. In addition to herniated discs in the cervical spine, peripheral damage to the median nerve or radial nerve is often responsible for negative effects on rotational movement. Bone fractures in the forearm have a direct impact on the range of motion of the forearm bones. Typical injuries of this type include wrist fractures involving the ulna and radius and fracture or dislocation of the proximal radial head. Rotational motion as rotational motion is not possible even after medical treatment, or is not allowed until the bone is fully consolidated.
