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Work-Related Ill Health
Published in Céline McKeown, Office Ergonomics and Human Factors, 2018
If the movement of the tendon within the sheath is restricted, the condition is referred to as stenosing tenosynovitis. The sufferer may be aware of a clicking or pulling sensation when trying to extend the fingers or thumb. This condition is often associated with overuse of the wrist during work activities. De Quervain’s tenosynovitis involves the abductor pollicis longus and extensor pollicis brevis tendons, which form the ‘anatomical snuffbox’, or small indent, clearly visible at the base of the thumb. Prolonged or repeated effort and unaccustomed work have been associated with the development of this condition, particularly when forceful gripping is combined with deviation of the wrist. Heavy reliance on the use of the thumb when completing an activity is also highlighted as precipitating the onset of this disorder, more so if the gripping action requires the thumb to be moved away from the main body of the hand, such as when spanning a large object with the fingers and thumb or using a tool like scissors. If the tendons of the finger flexors are compromised through overuse, the individual will be diagnosed as suffering from trigger finger. The finger flexors are responsible for closing the fingers to bring the fingertips in contact with the palm. If the tendon sheath becomes swollen, the tendon will not be able to move smoothly and will only be able to make jerky movements. This condition is often associated with overuse of the fingers and with repetitive or extended gripping of an object with a hard or sharp edge.
Work-Related III Health
Published in Céline McKeown, Office Ergonomics, 2007
If the movement of the tendon within the sheath is restricted, the condition is referred to as stenosing tenosynovitis. The sufferer may be aware of a clicking or pulling sensation when trying to extend the fingers or thumb. This condition is often associated with overuse of the wrist during work activities (Moore 1997). De Quervain’s tenosynovitis involves the abductor pollicis longus and extensor pollicis brevis tendons, which form the “anatomical snuffbox” or small indent clearly visible at the base of the thumb. Prolonged or repeated effort and unaccustomed work have been associated with the development of this condition, particularly when forceful gripping is combined with deviation of the wrist. Heavy reliance on the use of the thumb when completing an activity is also highlighted as precipitating the onset of this disorder, more so if the gripping action requires the thumb to be moved away from the main body of the hand, such as when spanning a large object with the fingers and thumb or using a tool like scissors. If the tendons of the finger flexors are compromised through overuse, the individual will be diagnosed as suffering from trigger finger. The finger flexors are responsible for closing the fingers to bring the fingertips in contact with the palm. If the tendon sheath becomes swollen, the tendon will not be able to move smoothly and will only be able to make jerky movements. This condition is often associated with overuse of the fingers and with repetitive or extended gripping of an object with a hard or sharp edge.
Remote Deictic Communication: Simulating Deictic Pointing Gestures across Distances Using Electro Muscle Stimulation
Published in International Journal of Human–Computer Interaction, 2020
Samuel Navas Medrano, Max Pfeiffer, Christian Kray
The next step in remotely communicating gestures between two parties was to induce a posture in the recipient that was approximately the same as the sender’s. More specifically, our aim was to induce a posture in recipient’s hand that approximated the position of the sender’s hand. For that purpose, we had to investigate which muscles to actuate and where to place the electrodes on the recipient’s body in order to achieve our goal. In an initial research stage, we tested lifting the recipient’s whole arm using EMS. The resulting movements were rough and imprecise as well as uncomfortable and invasive for the recipient users as several electrodes had to be placed around the shoulders and necks. For this reason, we decided to only focus on the hand instead, based on the ‘follow the force approach’ O. B. Kaul et al. (2016b). The ‘follow the force’ approach suggests to place four pairs of electrodes onto the user’s arm. By placing the electrodes on the positions described in the paper, a specific set of muscle can be activated in order to perform a specific set of movement: hand-up (activating musculus extensor digitorum), hand-down (activating musculus palmaris longus), hand-left (we performed radial abduction by activating musculus abductor pollicis longus and musculus extensor pollicis brevis), and hand-right (performing ulnar abduction by activating musculus flexor carpi ulnaris and musculus extensor carpi ulnaris). We aimed to place the electrodes in the positions suggested by the ’follow the force’ approach (as depicted in Figure 7) in order to achieve the same mapping of muscles and hand movements on users. However, we realized that individual physiological differences of participants were making it difficult to always stimulate the same muscle and achieve the same movement in different participants. Therefore, we established an individual calibration approach after having initially placed the electrodes as described above. It consisted of the experimenter using an exploratory trial-and-error strategy with each participant, where he adjusted the position of the electrodes until all four electrodes were able to activate muscles showing a clear up, down, left, and right hand movements.