Table 1.
Directional tuning of wrist muscle afferents
| Active | Passive | ||||
|---|---|---|---|---|---|
| Muscle | Unit type | Phase(s) | Theta (deg) | Phase(s) | Theta (deg) |
| EDC [V] | Ia | MT, PH | 38, 42 | n.p. | — |
| [IV] | Ia | n.s. | — | n.p. | — |
| [III] | Ia | MT, PH | 17, 12 | MT, PH | 16, 12 |
| [III] | II | PH | 337 | n.p. | — |
| [II] | II | MT, PH | 69, 77 | n.p. | — |
| ECU | Ia | MT, PH | 107, 108 | MT, PH | 89, 90 |
| II | PH | 52 | MT, PH | 85, 95 | |
| ECR | Ia | MT (MT) | 286 (277) | MT, PH | 300, 301 |
| Ia | MT | 215 | n.p. | — | |
| Ia | MT | 307 | n.p. | — | |
| Ia | n.p. | — | MT, PH | 281, 277 | |
| Ia | n.p. | — | MT, PH | 289, 287 | |
| II | MT | 309 | n.p. | — | |
| II | MT | 267 | MT | 276 | |
| II | n.s. | — | n.p. | — | |
| II | n.s. | n.s. | n.p. | — | |
| Ib | MT, PH | 116, 123 | n.s. | — | |
The entries in the columns marked ‘Phase(s)’ give the codes for the phases with significant directional tuning, ‘n.s.’ indicates that significant tuning was not significant in all phases of the trial whereas ‘n.p.’ indicates the test was not performed. Unit type abbreviations: Ia, muscle spindle primary afferent; II, muscle spindle secondary afferent; Ib, Golgi tendon organ afferent. In the case of one ECR Ia afferent, trials to all eight targets were completed twice with the results from the second trial given in parentheses. Theta values are given in degrees with 0/360 deg being the direction of a pure flexion movement, 90 deg pure radial deviation, 180 deg pure extension and 270 deg a pure ulnar deviation movement as illustrated in Fig. 3.