artificial limb

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artificial limb,

mechanical replacement for a missing limb. An artificial limb, called a prosthesis, must be light and flexible to permit easy movement, but must also be sufficiently sturdy to support the weight of the body or to manipulate objects. The materials used in artificial limbs include willow wood, laminated fibers and plastics, various metallic alloys, and carbon-fiber composites. More recently, 3D printers have been used to create much less expensive yet highly customizable, relatively easily produced prosthetics. One model of artificial leg is made of layers of stockinette cloth coated with plastic; it has duraluminum joints at the knee and ankle, rubber soles on the feet, and a leather cuff cushioning the stump. The cuff fits around the thigh like a corset, holding the artificial leg firmly in place, and connects to a leather belt around the waist. Often, spring joints are employed on foot pieces to give natural-looking movements. Microprocessors and an array of sensors are used to operate the mechanical and hydraulic system of some artifical legs, providing more natural locomotion. Sensors, microprocessors, and nerve stimulators can also be used to transmit stimulatory signals to nerve endings in the stump, allowing the amputee to feel more lifelike sensations from the artificial foot. Other artificial legs sacrifice a natural appearance to achieve greater mobility, such as the C-shaped carbon-fiber Flex-Foot used by amputees to participate in track-and-field sports. Artificial legs may also be secured by suction between socket and stump.

Artificial arms, not having to support the weight of the body, may be made of lighter metals and plastics. They are usually strapped to the trunk and controlled by a shoulder harness. Bionic arms have been developed that permit a person to use thought to control the limited movements of the motorized prosthesis. The commands are transmitted through chest muscle that has been surgically connected to the remaining nerves associated with the lost limb; electrodes linked to the artificial arm convert the sensed electrical signals of the muscle into arm movement. Tests with monkeys have shown that robotic arms can be controlled by the brain's electrical signals directly, using probes implanted in the brain and computer software to interpret the signals, and in laboratory experiments a person has similarly controlled a robotic arm.

Artificial hands vary in structure and utility; research and development has resulted in devices that are both cosmetic and functional. For example, an artificial hand has been devised that utilizes a split hook resembling a lobster claw; this is enclosed within a flexible plastic glove that can be made remarkably lifelike, even having fingerprints. The biceps muscle can be attached to the prosthesis by a surgical procedure called cineplasty, which permits grasping in the terminal device while dispensing with shoulder harnesses. A more recent artificial hand has separate motors for each finger, allowing for a more natural and useful grip and movement; the prosthesis is controlled by electrical signals generated by the arm muscles that normally control the hand. Software and electronics have improved sufficiently that some artificial hands can supply feedback to sensory nerves, enabling the user to feel the size, shape, and rigidity or flexibility of the object being handled.

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References in periodicals archive ?
He has been fitted with three different artificial limbs since
Adrian Cadiz ASSIUT, Upper Egypt - 2 May 2019: Assiut Governor Gamal Nour el Din and Indian Ambassador in Cairo Rahul Kulshreshth Thursday inaugurated a workshop for making artificial limbs to serve people with disabilities in the Upper Egypt.
Three-D printers make artificial limbs, "organs" so lifelike they appear to bleed and replacements for parts of jaw bones.
The writer seeks financial help of the government to arrange for him artificial limbs that could help him to work on computer as well.
Puri also presented artificial limbs to select beneficiaries," the Embassy added
Graham's artist's book Artificial Limbs. Image courtesy of the University of Victoria Libraries, Special Collections.
Furthermore, as many as 214 destitute children were provided wheel chairs, hearing aids, white canes and artificial limbs, besides financial assistance at a cost of Rs8.3 million.
A VETERAN who lost both legs in Afghanistan has called for a change in the law so he can donate his artificial limbs to other amputees in the UK.
A VETERAN who lost both his legs in a bomb blast in Afghanistan has called for a change to the law after being blocked from donating PS30,000 worth of artificial limbs to amputees in the UK.
MULTAN -- An 11-yearold who lost his limbs due to the power utility negligence in a locality of Karachi, has regained artificial limbs thanks to a Multan doctor, reported on Friday.
Damascus, SANA -- The Step Association for artificial limbs is preparing to launch a new project on the provision of 50 smart artificial upper limbs for children.

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