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Musculoskeletal system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The wrist is placed on the examination table with the hand supinated. The probe is placed on the palmar aspect of the wrist in the transverse plane, just proximal to the carpal tunnel (Fig. 3.4c), whose key anatomical structure is the flexor retinaculum. This contains the flexor pollicis longus tendon, the four flexor digitorum profundus tendons, the four flexor digitorum superficialis tendons and the median nerve.
Kinetic analysis of the wrist and fingers during fastball and curveball pitches
Published in European Journal of Sport Science, 2022
Shohei Shibata, Masahiro Kageyama, Yuki Inaba, Shinsuke Yoshioka, Senshi Fukashiro
The second objective of this study was to examine timing control between the wrist torque and finger torque. In this study, complete synchronization of the wrist flexion torque and finger flexion torque during a fastball pitch was found. This result is consistent with a part of the second hypothesis that the wrist torque (flexion and ulnar) and finger torque (flexion and adduction) during fastball and curveball pitches would synchronize completely. It was considered that synchronization of the wrist flexion torque and finger flexion torque could be because the extrinsic finger muscles cross the wrist. Werremeyer and Cole (1997) found that during wrist flexion movement when grasping an object, the timing of the initial peak in grip force roughly coincided with the timing of peak wrist acceleration. They explained that extrinsic finger flexors (i.e. flexor digitorum superficialis) were recruited to assist the intended wrist action. This seems to have enabled the wrist flexors (i.e. flexor carpi radialis) to overcome any loss in muscle force, whereas extrinsic finger flexors shorten during wrist flexion (Werremeyer & Cole, 1997). In addition, the hand inertia parameter is relatively small compared with those of other segments (de Leva, 1996). As a result, the influence of hand inertia on the joint torque is small, and the influence of segment acceleration on the joint torque is large. Shibata et al. (2018) reported that the influence of ball acceleration on the finger flexion torque was the largest of all parameters (finger length, ball acceleration, and finger inertia parameter). In other words, adjacent palm and finger segments have a small inertia, and they are apt to have a similar torque pattern. These results seem to demonstrate that the main reason for the similarity in peak torque timing is the anatomical arrangement of extrinsic finger muscles and the inertia characteristics of the palm and fingers.