THE PLANTAR REFLEX - RePub

FIGURE 8
Relative dimen.riom and weights ( aft~::r Temoval of tendom) of extensor halluci.r longus and
extemor hallztcis brevi.r.
movement of the great toe that can be seen even in aged patients to the
tiny extensor hallucis brevis muscle. In a post-mortem study of one human
subject (adult of unknown age) the extensor hallucis longus weighed 30.7
grams, the extensor hallucis brevis 0.9 gram (figure 8).
Activity in the tibialis anterior always accompanied the Babinski sign.
This not only confirms that the Babinski sign is part of the flexion reflex,
it also implies that in patients the thresholds for both muscles are
comparable, in keeping with the findings of Landau and Clare (1959).
Concomitant action of the tibialis anterior might be a valuable criterion
when plantar responses are equivocal. It is well-known that reflex
dorsiflexion of the foot is not pathological on its own, and in this study the
tibialis anterior was activated in three of the 40 control subjects.
Mechanical and electrical stimuli
Equivalence of electrical and mechanical stimuli with regard to the
capacity to elicit normal or pathological activity in the toe muscles has been
assumed not only by Kugelberg et al. (1960) and Grimby (1963 a), but
much earlier by Lewy (1909 a) and Yoshimura (1909), who applied faradic
-currents to the lateral plantar border. Although Lewy (1909 a) reported a
few 'unexplained' upgoing toe signs with this method of prolonged
electrical stimulation, accordance with the results after mechanical stimulation
was satisfactory. This parallelism cannot be extended to the brief
electrical stimuli employed in the more recent studies: the extensor
hallucis longus is activated in many control subjects (one third in the
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