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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.
Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Musculus dorsal interossei consists of four muscles. Insertion: They are on adjacent sides of the metatarsal bones. They are distally inserted in this way: The first insertion is on the medial side of the proximal phalanx of the second toe. The other insertion is between all the proximal phalanges of the second to fourth toes. Action: They are abductors of the toes and they flex the toes. Innervation is assured by the lateral plantar nerve.
A New Dataset and Neural Networks Models to Estimate the Joint Coordinates of Human Hand from Electromyographic Signals
Published in Cybernetics and Systems, 2022
S. Kirchhofer, T. Chateau, C. Bouzgarrou, J.-J Lemaire
For each subject, five records were performed: The subject was asked to stay at rest. The motion measurement was turned on with the hand about 20 cm above the desk. This record might be used for a calibration. At rest means, the subject relaxes his fingers while keeping the hand slightly parallel to the table.The subject was asked to move with slow movement. The time to get the hand from open to close is about 2 s. Each subject was asked to perform the most various gestures he can do. This record highlights the hand synergies and feeds the database with natural motions. We can see some gestures shared by almost all the subject as the open/closing hand, opposition of the thumb, counting on fingers, and spinning of wrist.For the third record, the request is almost the same as the second but with a higher velocity. All the subjects used to move faster with noticeable different speed. The goal is to emphasize dynamic effects of finger and wrist motion.This record is realized with the subject wrist fixed. The subject moves his fingers while trying to keep his wrist at rest. This test will be used to focus the regression on the reconstruction of the interphalanx joint coordinates. Dorsal and palmar interossei muscles tend to uncouple the motion of fingers, but their activities are not recorded with EMG sensors. As a consequence, it seems logical that the reconstruction of the finger joints needs more data.The last record gets closer to other datasets. It consists of six gestures repeated several times: Flexion/extension and deviation radial/ulnar of the wrist, opening/closing of the hand. The subject performs each gesture several times and recovering at rest between.