9 Springer-Verlag 1991 Functionally complex muscles of the cat hindlimb I. Patterns of activation across sartorius

Summary. The cat sartorius (SA) can be divided func-tionally into an anterior (SAa), knee extensor portion and a medial (SAm), knee flexor portion; it can be further subdivided anatomically by multiple nerve branches into parallel longitudinal columns that termi-nate in a distributed insertion at the knee with a con-tinuous range of moment arms. Thus, SA may be con-trolled by a discrete number of motoneuron task groups reflecting a small number of central command signals or by a continuum of activation patterns associated with a continuum of moment arms. To resolve this question, the activation patterns across the width of the SA were recorded with an electrode array during three kinemati-cally different movements- treadmill locomotion, scratching and paw shaking, in awake, unrestrained cats