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Key human anatomy and physiology principles as they relate to rehabilitation engineering
Published in Alex Mihailidis, Roger Smith, Rehabilitation Engineering, 2023
Qussai Obiedat, Bhagwant S. Sindhu, Ying-Chih Wang
Another factor to consider is how many joints a muscle crosses in the body. Single-joint muscles are those that span only one joint, while multi-joint muscles span two or more joints. The importance of this factor is that the force magnitude and joint range of motion (ROM) will vary depending on the relative position of each joint in the multi-joint muscles. For example, try to make a fist and flex your wrist, note the ROM of your wrist. Now flex your wrist while your hand is open. You will notice that the ROM increased. The reason for this increase is due to the length of the extensor digitorum muscle. The extensor digitorum spans over the wrist and the finger joints and is responsible for the extensions of the fingers and assists in the wrist extension as well. When you are making a fist with your hand, the tendons of the extensor digitorum are stretched, thus minimizing the available ROM for wrist flexion. Major joints in the upper and lower limbs, movements in each joint, and the muscles responsible for each movement are summarized in Table 3.4.
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
Generally, the EMG signal of the three muscles matched the periodicity of the accelerometric measurements (Figure 4). Only data from selected test persons could be analysed due to an overall low SNR < 5 in many participants. During the shocks, electrical activity ranged between 25.9 and 26.3% MVIC for the triceps muscle, 13.7 and 85.0% MVIC for the extensor digitorum muscle, and 32.7 and 89.6% MVIC for the flexor carpi ulnaris muscle, as calculated with the help of acceleration-based activity integrals. Figure 5 shows the course of the mean activity integral, expressed in relation to the static force employed in the blank test with push force only. From the data available, an overall tendency of a higher EMG activity during the shocks could be described as compared to the activity integrals in random vibration.
Feedback Control to a Static Target Angle in the Middle Finger Metacarpophalangeal Joint Using Functional Electrical Stimulation
Published in International Journal of Human–Computer Interaction, 2020
Kyosuke Watanabe, Makoto Oka, Hirohiko Mori
Humans perform physical movements by controlling muscles in two manners. First, humans control the direction of joint movement by reciprocal innervation, which contracts the main muscle, which leads the movement, and relaxes the antagonist muscle located on the opposite side of the main muscle (Ito, 1986). Second, humans perform detailed physical movements via the co-contraction of antagonistic muscles which leads to an increase in the stiffness of the joint (Gribble et al., 2003). Atsuumi et al. (2018) defined the ratio of the electrical stimulation intensity to the flexor digitorum muscle and the extensor digitorum muscle as the muscle antagonist ratio, and the sum was the muscle activity, and modeled a system with the muscle antagonist ratio as input and the force of the fingertips as output. The force of the fingertips was well estimated using the model. Therefore, we adopted the two concepts of muscle antagonist ratio and muscle antagonistic sum, referring to the research by Atsuumi et al. (2018). Atsuumi et al. (2018) defined the muscle antagonistic ratio based on the electrical stimulation intensity to each muscle; however, as described in section 4.1, there is a non-linearity relationship between the input dead zone and the muscle contraction force increase zone. Therefore, we defined the muscle antagonistic ratio and muscle antagonistic sum based on the force acting on the middle finger MP joint generated via electrical stimulation to the muscles. A formula for calculating the muscle antagonist ratio is as follows: