- Nervous system in Arthropoda is as advance as in Annelida. There is dorsal brain again connected with nerve ring to ventrae nerve cord.
- The arthropod nervous system consists of a dorsal brain and a ventral, ganglionated longitudinal nerve cord (primitively paired) from which lateral nerves extend in each segment. The system is similar to that of annelid worms, from which arthropods may have evolved. The neuromuscular organization of arthropods is quite different from that of vertebrates, in which one neuron supplies a number of muscle cells, together forming a functional motor unit. The small size of the muscles prohibits such an organization in arthropods. Instead, the state of contraction of an arthropod muscle is determined by which of several different types of neurons supplying one muscle cell are fired.
Nervous system in common cockroach
As already mentioned the nervous system in cockroach carries (I) The Central (II) Peripheral and (III) Sympathetic nervous system.
1.Central nervous system : this system comprises brain along with ventral nerve cord and the ganglia. (i) Brain: is in form of supra-oesophageal ganglion (bilobed) situated in the head above esophagus. Three pair of ganglia are fused alltogether in head region. The brain is divided in to three subparts. (a) Protocerebrum (b) Deuterocerebrum and (c) Tritocerebrum There is present a ventral sub-oesophageal ganglion which is contacted to brain by circum-oesophageal commissure. (ii) Ventrae nerve cord: the ventral nerve cord is double cord and situated on mid- ventral location. This starts from suboesophageal ganglion and ends at the last abdominal ganglion. There are nine ganglia in ventral nerve cord out of which three are present in thorax and six are abdomen.
2. Peripheral nervous system : by this system nerves are distributed to all body parts from ganglia. Paired optic nerves to eyes are supplied from protocerebrum where as paired antennary nerves to antennae are supplied from deuteron-cerebrum in the same manner thoracic ganglia supply nerves to wing, leg/muscles and other thorasic and abdominal organs.
3. Sympathetic nervous system : some authors have also mentioned this system as stomogastric nervous system. There are total four ganglia namely (i) frontal ganglion (ii) hypocerebral ganglion (iii) ingluvial ganglion and (iv) proventriculuas ganglion. The nerves are supplied to pharyx, labrum and clypeus. Esophagus is supplied nerves from hypo-cerebral ganglion. Crop is supplied nerves from ingluvial ganglion.The proventricular gangalion is present on the surface of proventriculus. A retro-cerebral complex is also present above hyprocerebral ganglion. Two lobes called corpora cardiac and corpora allata are important part of this complex. Corpora cardiac is responsible for regulation of heart beats and peristalsis of foregut as well. Corpora allata is responsible for metamorphosis and also helps in reproduction through hormone secretion.