Q.Describe nervous system of cockroach.

The cockroach's nervous system is ventral, solid and ganglionated, with three parts.

Step 1. Central Nervous System (CNS). A nerve ring in the head is formed by the paired supra-oesophageal (cerebral) ganglia — together called the brain, each fused from a protocerebrum, deutocerebrum and tritocerebrum — connected by circum-oesophageal connectives to the bilobed sub-oesophageal ganglion below the oesophagus. From the sub-oesophageal ganglion arises the ventral nerve cord, a double cord of nine pairs of segmental ganglia: three larger thoracic pairs, and six abdominal pairs (the sixth, in the seventh abdominal segment, is the largest; the sixth segment itself has no separate ganglion).

Step 2. Peripheral Nervous System (PNS). Nerves branch from these ganglia to the body's sense organs and muscles: six pairs from the cerebral ganglia to the eyes, antennae and labrum; nerves from the sub-oesophageal ganglion to the mandibles, maxillae and labium; nerves from the thoracic ganglia to the wings, legs and thoracic organs; and nerves from each abdominal ganglion to that segment's organs. …

Present the three named divisions (CNS, PNS, ANS) in turn, listing the g …

• Placing the ventral nerve cord's ganglia count wrong (it is nine pairs total: three thoracic + six abdominal, not ten segments' worth, since the sixth abdominal segment has no gang …