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

Hu X, Suresh NL, Xue C, Rymer WZ - Front Physiol (2015)

Bottom Line: 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.We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction.Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

View Article: PubMed Central - PubMed

Affiliation: Sensory Motor Performance Program, Single Motor Unit Lab, Rehabilitation Institute of Chicago Chicago, IL, USA.

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.

No MeSH data available.


Related in: MedlinePlus

X and Y centroid locations of the RMS in different tasks. (A) The Y coordinate of the centroid in the longitudinal direction was calculated as a percentage of the forearm length from the olecranon process (0%) to the styloid process (100%) of the ulna. Error bars represent standard errors between subjects. (B) The X coordinate of the centroid in the circumferential direction was calculated as a percentage of forearm circumference from radial–flexor to ulnar–extensor (0% on the medial side of the forearm to flexor, then to extensor, and to 100% on the medial side of the forearm).
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Figure 4: X and Y centroid locations of the RMS in different tasks. (A) The Y coordinate of the centroid in the longitudinal direction was calculated as a percentage of the forearm length from the olecranon process (0%) to the styloid process (100%) of the ulna. Error bars represent standard errors between subjects. (B) The X coordinate of the centroid in the circumferential direction was calculated as a percentage of forearm circumference from radial–flexor to ulnar–extensor (0% on the medial side of the forearm to flexor, then to extensor, and to 100% on the medial side of the forearm).

Mentions: The locations of the centroid at different task conditions are illustrated in Figure 4. The Y coordinate of the centroid (Figure 4A) revealed that the centroid of the index finger was close to 60% from the olecranon process, whereas the centroid of the middle finger was ~30% from the olecranon process. The centroids of the ring and little fingers were 40–50% from the olecranon process. With a high contraction effort and dynamic contraction conditions, the centroids in the ring and little finger extension as well as the four-finger extension tended to shift toward the proximal end, whereas the centroid of the middle finger extension tended to shift toward the distal end. The Two-way ANOVA showed a significant finger × effort level interaction [F(4, 36) = 6.03, p = 0.001] and finger × constraint interaction [F(4, 36) = 2.93, p = 0.034]. The centroids of the index finger were significantly lower (more distal) than the rest of the fingers (p < 0.05), and the centroids of the middle finger were significantly higher (more proximal) than the rest of the fingers (p < 0.05). The centroids of the ring finger in the static conditions and dynamic low condition were higher than the centroids of the little finger (p < 0.05).


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

Hu X, Suresh NL, Xue C, Rymer WZ - Front Physiol (2015)

X and Y centroid locations of the RMS in different tasks. (A) The Y coordinate of the centroid in the longitudinal direction was calculated as a percentage of the forearm length from the olecranon process (0%) to the styloid process (100%) of the ulna. Error bars represent standard errors between subjects. (B) The X coordinate of the centroid in the circumferential direction was calculated as a percentage of forearm circumference from radial–flexor to ulnar–extensor (0% on the medial side of the forearm to flexor, then to extensor, and to 100% on the medial side of the forearm).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593961&req=5

Figure 4: X and Y centroid locations of the RMS in different tasks. (A) The Y coordinate of the centroid in the longitudinal direction was calculated as a percentage of the forearm length from the olecranon process (0%) to the styloid process (100%) of the ulna. Error bars represent standard errors between subjects. (B) The X coordinate of the centroid in the circumferential direction was calculated as a percentage of forearm circumference from radial–flexor to ulnar–extensor (0% on the medial side of the forearm to flexor, then to extensor, and to 100% on the medial side of the forearm).
Mentions: The locations of the centroid at different task conditions are illustrated in Figure 4. The Y coordinate of the centroid (Figure 4A) revealed that the centroid of the index finger was close to 60% from the olecranon process, whereas the centroid of the middle finger was ~30% from the olecranon process. The centroids of the ring and little fingers were 40–50% from the olecranon process. With a high contraction effort and dynamic contraction conditions, the centroids in the ring and little finger extension as well as the four-finger extension tended to shift toward the proximal end, whereas the centroid of the middle finger extension tended to shift toward the distal end. The Two-way ANOVA showed a significant finger × effort level interaction [F(4, 36) = 6.03, p = 0.001] and finger × constraint interaction [F(4, 36) = 2.93, p = 0.034]. The centroids of the index finger were significantly lower (more distal) than the rest of the fingers (p < 0.05), and the centroids of the middle finger were significantly higher (more proximal) than the rest of the fingers (p < 0.05). The centroids of the ring finger in the static conditions and dynamic low condition were higher than the centroids of the little finger (p < 0.05).

Bottom Line: 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.We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction.Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

View Article: PubMed Central - PubMed

Affiliation: Sensory Motor Performance Program, Single Motor Unit Lab, Rehabilitation Institute of Chicago Chicago, IL, USA.

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.

No MeSH data available.


Related in: MedlinePlus