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The Nervous System of Cockroach can be Divisible into Three Parts:
(i) The central nervous system,
(ii) Peripheral nervous system,
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(iii) Visceral or sympathetic nervous system.
The central nervous system of cockroach (Fig. 1.2) consists of the supra-oesophageal or cerebral ganglia, sub-oesophageal ganglia and circum oesophageal connectives in the head and a double ganglionated ventral nerve cord in the thorax and abdomen. The brain or supra-oesophageal ganglia are a pair of large, closely apposed ganglia in the head.
From the lower side of the brain arises a pair of short, thick circum-oesophageal connective which run round the oesophagus and meet the sub-oesophageal ganglia. The sub- oesophageal ganglia are a pair of large ganglia present on the ventral side of oesophagus. The ventral nerve cord runs along the ventral wall of thorax and abdomen and possesses nine fused ganglia, out of which three are thoracic and six are abdominal in position.
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Out of the six abdominal ganglia, the First Five are present in the first five abdominal segments and the last one is present a little behind the sixth abdominal segment. The thoracic and abdominal ganglia are resulted due to the fusion of paired ganglia except the sixth abdominal ganglion which is formed by the fusion of several ganglia and hence largest in size.
The peripheral nervous system consists of nerves starting from the ganglia of central nervous system and supplying to various organs in the periphery. From the brain arises a pair of optic and antennary nerves supplying to eyes and antennae respectively. The suboesophageal ganglia supplies paired nerves to mandibles, maxillae and labium.
The thoracic and first five abdominal ganglia give off paired segmental nerves to appendages, muscles and other structures. From the sixth abdominal ganglion arise several nerves which are supplied to different parts of sixth and the remaining posterior segments. The sympathetic or visceral nervous system consists of a small frontal ganglion in front of the brain dorsal to pharynx, an oesophageal ganglion on the dorsal side of oesophagus and a large visceral ganglion on the dorsal surface of crop.
