THORAX AND THORACIC SEGMENTS AND THEIR APPENDAGES

• The thorax is the middle body region between the head and abdomen.
• The insect thorax has three segments:i.e. the prothorax, mesothorax, and metathorax.
• The anterior segment, closest to the head, is the prothorax; its major features are the first pair of legs and the pronotum.
• The middle segment is the mesothorax; its major features are the second pair of legs and the anterior wings, if any.
• The third, the posterior, thoracic segment, abutting the abdomen, is the metathorax, which bears the third pair of legs and the posterior wings.
• Each segment is delineated by an intersegmental suture. Each segment has four basic regions.

a) A thickened dorsal plate on each segment of the body of an insect is called the tergum (or notum) to distinguish it from the abdominal terga.

b) The two lateral regions are called the pleura (singular: pleuron) and the ventral aspect is called the sternum.

• In turn, the notum of the prothorax is called the pronotum, the notum for the mesothorax is called the mesonotum and the notum for the metathorax is called the metanotum.
• The legs arise on the leura and wings are articulated between the notal and pleural regions.
• There is also the mesopleura and metapleura, as well as the mesosternum and metasternum.