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Designing for Hand and Wrist Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Thenar muscles (at the base of the thumb) lie on the palmar side of the hand, along the first metacarpal. Feel the muscles by flexing your thumb to touch your index finger. Find the hypothenar muscles, a group of muscles on the palm, at the base of the little finger. They abduct the little finger and assist with little finger flexion. The interossei and lumbrical muscles abduct and adduct the fingers and help to stabilize their positions. These muscles are located in the deep spaces between the metacarpal bones in the palm. They are difficult to feel, except for the interosseous muscle between the thumb and the index finger. When you pinch the web space between the thumb and index finger, you can feel the 1st dorsal interosseous muscle on the dorsum of the hand as you move your thumb toward and then away from your index finger. All these muscles work together to stabilize and flex, extend, abduct, adduct, and oppose the digits. There are no muscle bellies in the fingers along the phalanges—only tendons arising from either the forearm’s extrinsic muscles or the intrinsic muscles of the hand. As with muscles throughout the body, the names of the muscles acting on the hand describe what they do, where they attach, and occasionally some other characteristic. For example, opponens pollicis, in the thenar group, is a muscle that moves the thumb (pollex) to oppose other fingers and flexor digiti minimi flexes the little finger.
Acute physiological and functional effects of repetitive shocks on the hand–arm system: a pilot study on healthy subjects
Published in International Journal of Occupational Safety and Ergonomics, 2023
Jonathan Witte, Alexandra Corominas, Benjamin Ernst, Uwe Kaulbars, Robert Wendlandt, Hans Lindell, Elke Ochsmann
Differences of ΔT between the exposed hand and the non-exposed hand could be demonstrated for the shock exposures, as opposed to the random vibration signal. This could be due to a central vasoconstrictor response mediated through the sympathetic system and/or local vasoactive substances which is observed with HAV [51–55]. Repetitive shocks of the same rms magnitude express much higher peak acceleration values that possibly additionally impact on the ipsilateral hand–arm system, e.g., wall shear stress on the endothelium [56] or microtraumas known from the aetiology of hypothenar hammer syndrome [57]. Last, it remains controversial whether skin temperature measurements can effectively depict acute vascular effects [58,59], the more so as thermography did not reach high levels of sensitivity or specificity for diagnosing HAVS [60]. Nonetheless, Thompson and Griffin [61] and Mirbod et al. [62] were able to correlate plethysmographic blood flow measurements with skin temperatures, concluding that these two parameters described the same vascular mechanism. With this, infrared thermography should be considered for use in occupational health prevention in the future, provided that confounders like room temperature or previous physical activity are well controlled.
Exposure to hand-arm vibrations in the workplace and the occurrence of hand-arm vibration syndrome, Dupuytren’s contracture, and hypothenar hammer syndrome: a systematic review and meta-analysis
Published in Journal of Occupational and Environmental Hygiene, 2023
Heike Gerger, Karen Søgaard, Erin M. Macri, Jennie A. Jackson, Roy G. Elbers, Rogier M. van Rijn, Bart Koes, Alessandro Chiarotto, Alex Burdorf
Musculoskeletal disorders of the hands and wrists are highly prevalent in many occupations. There is an indication that the use of hand-held vibrating tools is related to adverse effects on the hands and wrists of workers, including hand-arm vibration syndrome (HAVS, which includes vibration-induced white finger or VWF), Dupuytren’s contracture (DC), and hypothenar hammer syndrome (HHS) (Descatha et al. 2011; Nilsson et al. 2017; Mathieu et al. 2020). HAVS is a disorder of the hand affecting mostly the fingers and is composed of vascular, neurological, and muscular components (Burström et al. 1998; Ye et al. 2015). VWF presents as deteriorated peripheral blood circulation and may encompass disturbed function of nerves, soft tissue, and bones in the hand (Cherniack 1990) with symptoms such as numbness and tingling in the fingers, loss of hand or arm strength, whitening of the fingertips, and problems with precision finger tasks. DC is a slowly progressive and irreversible disabling flexion of the fingers (Picardo and Khan 2012) which results in deteriorated hand grip function. Finally, HHS is a condition of the hand with reduced blood flow to the hand and fingers (Cooke 2003).
Kinetic analysis of push-up exercises: a systematic review with practical recommendations
Published in Sports Biomechanics, 2022
Wissem Dhahbi, Helmi Chaabene, Anis Chaouachi, Johnny Padulo, David G Behm, Jodie Cochrane, Angus Burnett, Karim Chamari
The narrower hand position exhibited lower PF or axial elbow-joint force compared to the wider hand position (Donkers et al., 1993; Gouvali & Boudolos, 2005). The study of Chuckpaiwong and Harnroongroj (2009) revealed that a wider hand position generates a higher peak pressure on the medial side of the palm, whereas a narrower hand position induces a higher peak pressure on the lateral side of the palm. Therefore, a wider hand position may be the best choice when performing push-ups to prevent hypothenar pain, while a narrower hand position may be appropriate to prevent thenar or lunate pain (Table 5).