The ability to position the fingers and thumb in precise postures is vital for the highly coordinated use of the hand and the wrist has a significant role to play in this function. The shoulder blade and the shoulder perform the gross positioning of the arm, the elbow places the hand at varying distances from the body, the forearm dictates the angle of the wrist and the wrist performs the final positioning of the hand. The closer to the hand the body parts come the more precise and fine the movement becomes.
The wrist joint is placed between the hand and the forearm bones and is made up of a group of eight small bones which occur in two rows with articulations on one side with the radius and ulna and on the other side with the metacarpals. The metacarpals, the long bones in the palm of the hand, run from the further row of carpal bones down to the knuckles where they join the fingers. The metacarpals are arranged in an almost parallel pattern and are long and slim bones, giving them the ability to rotate around each other to some degree and improve grip.The Human Wrist Joint
Human hand function is a highly complex process as the thumb, fingers and hand are placed in a precise posture to suit the task being performed, with the wrist performing a pivotal role. The major, less precise, arm positioning is provided by the shoulder and shoulder blade, the body to hand distance is controlled by the elbow, the wrist angle is set by the forearm and the last adjustments of hand position are performed by the wrist. The movements become more precise the closer the joint becomes to the wrist.
The manoeuvrability of the thumb is one of the most amazing parts of the function of the hand. The "opposable thumb" that humans possess and which apes do not is one of the defining characteristics of precision movement and control. The metacarpal of the thumb on the outside of the hand is not inline with all the others but rotated inwards, having the ability to rotate further inwards to allow the end of the thumb to participate in grasping with one of the fingers. The thumb has a very specialised joint at the junction of the metacarpal and carpal, allowing the specialised movement.
The movements of the carpal bones can be in unison in small amounts as they move together to allow a movement to occur. As the hands move small amplitudes of movement occur between the individual carpal bones and the carpal rows. The metacarpals are able to rotate around their long axes which allows the palm to be curled into a cupped position. As the palm moulds round to assist gripping it also allows the fingers to align so that they can effectively grip at the correct angle. Any loss of the accessory movements of the carpals and metacarpals can reduce the ability of the hand to function adequately.
The heavy use of the hands in manual work such as lifting and moving large objects, manipulating heavy machines and pulling ropes can damage the function of the wrist. High mechanical forces are generated when the hand grips something hard, squeezing the wrist bones between the metacarpal bones and the radius and ulna of the forearm. This can allow a reduction of the accessory movements between the individual wrist bones. The lunate bone can be moved from its position with painful consequences if the wrist is extended with force.
A fall on the outstretched hand (FOOSH) is the most typical reason for the wrist to be extended forcibly and a Colles fracture is a common result where the break is located in the last inch of the radius and ulna near the wrist. Older women are most likely to suffer from this fracture and although most attention is concentrated on the fracture there is often a significant soft tissue injury of the wrist bones as well. The fracture will heal in five or six weeks but pain, weakness and functional difficulty may persist for much longer, related to some extent to the loss of individual movements between the carpal bones. - 14130
The wrist joint is placed between the hand and the forearm bones and is made up of a group of eight small bones which occur in two rows with articulations on one side with the radius and ulna and on the other side with the metacarpals. The metacarpals, the long bones in the palm of the hand, run from the further row of carpal bones down to the knuckles where they join the fingers. The metacarpals are arranged in an almost parallel pattern and are long and slim bones, giving them the ability to rotate around each other to some degree and improve grip.The Human Wrist Joint
Human hand function is a highly complex process as the thumb, fingers and hand are placed in a precise posture to suit the task being performed, with the wrist performing a pivotal role. The major, less precise, arm positioning is provided by the shoulder and shoulder blade, the body to hand distance is controlled by the elbow, the wrist angle is set by the forearm and the last adjustments of hand position are performed by the wrist. The movements become more precise the closer the joint becomes to the wrist.
The manoeuvrability of the thumb is one of the most amazing parts of the function of the hand. The "opposable thumb" that humans possess and which apes do not is one of the defining characteristics of precision movement and control. The metacarpal of the thumb on the outside of the hand is not inline with all the others but rotated inwards, having the ability to rotate further inwards to allow the end of the thumb to participate in grasping with one of the fingers. The thumb has a very specialised joint at the junction of the metacarpal and carpal, allowing the specialised movement.
The movements of the carpal bones can be in unison in small amounts as they move together to allow a movement to occur. As the hands move small amplitudes of movement occur between the individual carpal bones and the carpal rows. The metacarpals are able to rotate around their long axes which allows the palm to be curled into a cupped position. As the palm moulds round to assist gripping it also allows the fingers to align so that they can effectively grip at the correct angle. Any loss of the accessory movements of the carpals and metacarpals can reduce the ability of the hand to function adequately.
The heavy use of the hands in manual work such as lifting and moving large objects, manipulating heavy machines and pulling ropes can damage the function of the wrist. High mechanical forces are generated when the hand grips something hard, squeezing the wrist bones between the metacarpal bones and the radius and ulna of the forearm. This can allow a reduction of the accessory movements between the individual wrist bones. The lunate bone can be moved from its position with painful consequences if the wrist is extended with force.
A fall on the outstretched hand (FOOSH) is the most typical reason for the wrist to be extended forcibly and a Colles fracture is a common result where the break is located in the last inch of the radius and ulna near the wrist. Older women are most likely to suffer from this fracture and although most attention is concentrated on the fracture there is often a significant soft tissue injury of the wrist bones as well. The fracture will heal in five or six weeks but pain, weakness and functional difficulty may persist for much longer, related to some extent to the loss of individual movements between the carpal bones. - 14130
About the Author:
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about physiotherapy, physiotherapy, physiotherapists in Birmingham, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
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