Central Nervous System of Cockroach / Grasshopper
I. Brain or Supra Oesophageal Ganglion:
It is anterior most ganglionic mass above the oesophagus between the supporting apodermes of the tentorium. It comprises of the following components.
1. Protocerebrum: Represent the fused ganglia of the acron and preantennal segment. It is the anterior most and largest part of the brain consists of protocerebral lobes and optic lobes. It innervates the compound eyes and ocelli.
2. Deutocerebrum: It is the second or central part of the brain. Represent the fused ganglia of the antennal segment. It innervates antennae.
3. Tritocerebrum: It is the posterior part of the brain formed by the ganglia of the third or intercalary segment of the head. Innervates labrum and unite the brain with forntal ganglion.
Circum-oesophagus and joining supra-oesophageal ganglion with sub-oesophageal ganglion
II. Sub-oesophageal Ganglion: It is oval shaped, lines below the oesophagus in the head region. It is formed by the fusion of the ganglia of the Mandibular, maxillary and labial segments. It gives off paired nerves supplying their respective appendages.
III. The Ventral Nerve Cord: Consists of series of ganglia lying on the floor of thorax and abdomen.
1. Thoracic ganglia: The first three ganglia are situated one in each of the thoracic segment called thoracic ganglia. It controls the locomotory organ. Each ganglion gives off two pairs of principal nerves, one of which supplies the general musculature of the segment and the other innervates the muscles of the legs and wings.
2. Abdominal Ganglia: Six in number, lie in the abdomen. Each abdominal ganglion gives off a pair of principal nerves to the muscles of its segment.
3. Connective: These are two longitudinal cords, joining one pair of ganglia with those preceding and succeeding it.
4. Commissures: These are the transverse fibers; unite the pair of ganglia of the system.