Improved evaluation of back muscle SEMG characteristics by modelling R. Grassme, D. Arnold, Ch. Anders, J.P. van Dijk, D.F. Stegeman, W. Linß, I. Bradl, N.P. Schumann, H.Ch. Scholle  Pathophysiology  Volume 12, Issue 4, Pages 307-312 (December 2005) DOI: 10.1016/j.pathophys.2005.09.011 Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 1 Illustration of action potential propagation and correlation of bipolar SEMG channels. Muscle fibres have tendons T (causing non-propagating long range field components) and endplates E. Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 2 Positions of surface EMG electrodes in the back region. The electrode columns are positioned for investigations of E—m. erector spinae and L—m. latissimus. Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 3 Experimental SEMG cross correlation functions calculated from m. latissimus: (A) no filtering (more detailed: only high pass, fu=28Hz to suppress movement artefacts; CRC=1); (B) m. latissimus, high pass, fu=105Hz (CRC=1); (C) regions with possible EMG-sources (active fibre populations)—S1 and S2 lie anywhere in the areas A1 and A2, source S2 is stronger than S1. Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 4 Experimental SEMG cross correlation functions from m. erector spinae for different positions of the covariance reference channel (CRC) which are indicated by arrows: (A) CRC=14, (B) CRC=8, (C) CRC=2. High pass filtering only for suppression of movement artefacts, i.e., fu=28Hz. Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 5 SEMG cross correlation functions from m. erector spinae: (A) no high pass filtering (CRC=12); (B) high pass, fu=84Hz (CRC=12); (C) high pass, fu=140Hz (CRC=12). Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 6 Morphology of back muscles: (A) anatomy of musculus longissimus (m. erector spinae). An aponeurosis (ap) is located at the surface. (B) Scheme describing the substantial features of m. longissimus for our model. Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 7 Two simple models for groups of muscle fibres in musculus longissimus. (A) Fibres parallel to the axis of the electrode column. These fibres can be located superficial (model A-S) or deep (model A-D). (B) Fibres are inclined to the axis of the electrode column (26°). The fibre–tendon transition lies beneath the electrode column. Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 8 Simulated cross covariance functions (ccvf) with model A-D, for deep fibres. Simulation with 170 independent motor units (MUs) at random positions in z-direction. MU depth=3cm and length=12cm (z-direction and axes of the MUs are parallel to the vertebral column). Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 9 Simulated cross covariance functions (ccvf) with model A-S, for superficial fibres. Simulation with 170 independent motor units at random positions in z-direction. MU depth=0.5cm and length=12cm (z-direction and the axes of the MUs are parallel to the vertebral column). Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions

Fig. 10 Simulated cross covariance functions (ccvf) with model B, for superficial tendons. Simulation with 40 independent motor units at random positions in z-direction. MU depth=0.25cm and length=12cm (z-direction parallel to the vertebral column; angle to fibre axes=26°). Pathophysiology 2005 12, 307-312DOI: (10.1016/j.pathophys.2005.09.011) Copyright © 2005 Elsevier Ireland Ltd Terms and Conditions