Fig 5.
Tracings of groups of muscle spindles, tendon organs and extrafusal muscle fibres teased from intrinsic hind-foot muscles of the cat, all drawn to the same scale. Colour code as in Fig.3. dl, deep lumbrical (flexor profundus); the tendon organ is a rare occurrence in this muscle; extrafusal muscle fibres (light brown) extend the full length of the fascicle alongside the group of spindles. sl, superficial lumbrical (flexor superficialis; two spindles partially in parallel shown above an extrafusal fascicle. adqm, abductor digiti quinti medius: one of the spindles is in series with a tendon organ. odq, opponens digiti quinti. qp, quadratus plantae; the short pole of the spindle is complete. calc, calcaneometatarsalis. fdb, flexor digitorum brevis. Note that the spindles are longer than the extrafusal muscle fibres in calc and fdb. Values of NA for each of these muscles are given on the right.