The buccal nervous system ofoctopus

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Abstract
The operations of killing and eating food by an octopus are under the control of a series of nervous centres. The poison centre lies most posteriorly and is probably activated first, since it lies close to endings of fibres from the arms. The fibres of the nerves to the posterior salivary gland run without synapse from the superior buccal lobe to the glands, passing first far forward and then back along the duct. There is thus no peripheral synapse on this path, perhaps because no continuing rhythmic operations are involved in the secretion, and no reflex guidance is needed. The actual injection of the poison by the salivary papilla is controlled through the subradular ganglia. The cerebro-subradular connectives arise from the front of the superior buccal ganglia, near the entrance of the labial nerves, and run direct to the subradular ganglia, bypassing the inferior buccal ganglion. The interbuccal connectives also arise from the front of the superior buccal lobe and run to the inferior buccal ganglion. The inferior buccal ganglion sends nerves to the muscles of the jaws and radula and to the anterior salivary glands, buccal palps and oesophagus. Through the sympathetic nerve it communicates with the gastric ganglion. The inferior buccal ganglion has a complicated internal structure. From its outer surface arise numerous strands of the juxtaganglionic tissue, which end at the surfaces of the buccal sinus. The proportion of large cells decreases in the sequence posterior buccal, superior buccal, inferior buccal, subradular and gastric ganglia.

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