Extracting extensor digitorum communis activation patterns using high-density surface electromyography

Abstract

The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions. The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7 × 9) surface electromyogram (EMG) recordings. The muscle activation map (based on the root mean square of the EMG) was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic). Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal–distal direction than in the radial–ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

Activity patterns of extrinsic finger flexors and extensors during movements of instructed and non-instructed fingers

“…For the ED, the index and middle finger clusters showed the least amount of overlap. Yet even with this overlap the location of the extensor clusters was consistent with those reported in previous studies (Gallina and Botter, 2013;Gazzoni et al, 2014;Hu et al, 2015, Leijnse et al, 2008. The flexor muscle location has mainly been determined using ultrasound and cadaver studies.…”

“…The simultaneous activation of muscle regions corresponding to non-instructed fingers has been reported in several studies for the FDS, FDP and ED muscles (Butler et al, 2005;Darling and Cole, 1990;Hu et al, 2015;Leijnse et al, 2008;McIsaac and Fuglevand, 2007;Reilly and Schieber, 2003;van Duinen et al, 2009). One study looking at the FDP using intramuscular EMG showed that muscle activation of the non-instructed fingers was lower the larger the distance was to the instructed finger (Reilly and Schieber, 2003).…”

Single finger movements in the aging hand: changes in finger independence, muscle activation patterns and tendon displacement in older adults

“…was to identify the regions that correspond to the FDS muscle regions of the different fingers. Cluster positions generally corresponded to the underlying anatomy as described in the literature (Frohse and Frankel 1908) and were consistent with electrode placement reported in previous studies (Bickerton et al 1997;Leijnse et al 2008;Henzel et al 2010;Gallina and Botter 2013;Gazzoni et al 2014;Hu et al 2015).…”

Extracting and Classifying Spatial Muscle Activation Patterns in Forearm Flexor Muscles Using High-Density Electromyogram Recordings

“…The activation of the middle finger was located in the most radial region with some degree of overlap with the index and little fingers. Unlike the extensor digitorum muscle activation, 3,13 the activation patterns of flexors in the proximal-distal direction is less distinguishable, despite the elongated muscle orientation. Overall, the IZ distribution is more distinct across different fingers in comparison with the macro-level muscle activation (RMS map) patterns.…”

“…11,12 Using recently developed high-density (HD) EMG recording techniques with closely distributed electrode grid placed on the skin surface, several studies have quantified the overall patterns of muscle activation on different extrinsic finger extensor muscles. 13,14 However, the features of distinct activation patterns of forearm flexor muscles, which include both global muscle and localized motor unit activities during individual finger flexions, have not been fully investigated.…”