THE INNERVATION AND PHYSIOLOGY OF THE EXTRINSIC BUCCAL RETRACTOR MUSCLES OF PHILINE APERTA (LINNAEUS)

Publisher Website
Google Scholar
Abstract
Two buccal mass retractor muscles of Philine are innervated by at least 4 excitatory motoneurons, whose cell bodies lie in the buccal and the cerebral ganglia. The muscle fibres respond to action potentials generated in the motoneurons or their axons with excitatory junction potentials (ejps), each of which is followed by a small twitch-like contraction. Both the electrical and mechanical responses facilitate and summate with repetitive stimulation. A large ventrally located cerebral neuron (VGC) inhibits tension development in the muscle by reducing the amplitude of the excitatory junction potentials from and identified buccal motoneuron. Acetylcholine reversibly depolarises and causes tonic contraction of the muscles. This action is partially antagonised by hexamethonium, which also blocks the ejps from two axons in the buccal and one in the pedal nerve 9. 5-Hydroxytryptamine potentiates the ejp from the identified buccal motoneuron and enhances the rate of relaxation. Histamine reduces the amplitude of the presumed cholinergic buccal nerve ejps, but does not affect the hexamethonium sensitive ejp in the pedal nerve 9. In this respect its action resembles that of the ventral giant cell.

This publication has 0 references indexed in Scilit: