後大脳は脳でもっとも小さな領域で特徴的な構造をもつ神経叢は見られない．後大脳は縦連合により後方の食道下神経節とつながり，また前額神経節は，心臓や消化管の内臓筋を支配する口胃神経系の中枢であり，回帰神経を経て食道下神経節とつながる．
Tritocerebrum
The tritocerebrum is the smallest region and little studied. In the primitive insect ground plan, the tritocerebrum is connected to the suboesophageal ganglian by a pair of circumoesophageal connectives (for example in locusts, crickets, cockroaches), in more derived groups, the tritocerebrum, the posterior part of the deutocerebrum, and the suboesophageal ganglion are fused such that it can be difficult to determine the borders between them. The tritocerebrum contains at least two commissures, one of which is running above the oesophagus in the primitive ground plan. The tritocerebrum receives sensory inputs from the labrum through the labral nerve, from the tegument through the tegumentary nerve, and at least in some insects also direct sensory input from the mouthparts (mandible, maxilla, and labium). The frontal nerves of the tritocerebra on each side run to the frontal ganglion that connects the brain and the stomatogastic system, lying dorsal with respect to the oesophagus and innervating cardiac and gastrointestinal muscles. The frontal ganglion is connected to the hypocerebral ganglion thourgh the recurrent nerve.In some insects (honeybee), the frontal and labral nerves are fused at the root to form a labro-frontal nerve. Tritocerebrum is connected to suboesophageal ganglion through a pair of connective. Frontal ganglion is center of stomatogastric ganglion innervating cardiac and gastrointestinal muscle and is connected to suboesophageal ganglion via recurrent nerve.