Motor Unit Number Estimation of the Second Lumbrical Muscle in Human Hand

Ya Zong; Zhiyuan Lu; Maoqi Chen; Lianfu Deng; Qin Xie; Ping Zhou

doi:10.3389/fphys.2022.854385

Motor Unit Number Estimation of the Second Lumbrical Muscle in Human Hand

Front Physiol. 2022 Feb 22:13:854385. doi: 10.3389/fphys.2022.854385. eCollection 2022.

Authors

Ya Zong¹, Zhiyuan Lu², Maoqi Chen², Lianfu Deng³, Qin Xie¹, Ping Zhou²

Affiliations

¹ Department of Rehabilitation Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
² Faculty of Rehabilitation Engineering, University of Health and Rehabilitation Sciences, Qingdao, China.
³ Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases, Department of Orthopaedics, Shanghai Institute of Traumatology and Orthopaedics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

Abstract

The number of motor units of the lumbrical muscles in human hand has not been explored. The objective of this study was to fill this gap by estimating the number of motor units in the second lumbrical muscle. Compound muscle action potential scan of the second lumbrical muscle was performed in 12 healthy subjects, with 10 of them being tested on two separate occasions. Motor unit number estimation (MUNE) was derived from the MScanFit program. The average MUNE of the second lumbrical muscle was 41.6 ± 2.1 (mean ± standard error) from 12 subjects in the first test, and 42.0 ± 2.2 from 10 of the 12 subjects in the retest, demonstrating excellent measurement reliability. Findings of the study provide novel information about the motor unit number of the second lumbrical muscle in human hand. The relatively low motor unit number in the muscle can facilitate motor unit investigations, especially at high level muscle activation.

Keywords: CMAP scan; MScanFit; compound muscle action potential; motor unit number estimation; second lumbrical muscle.