collective term for cell groups in the caudal midbrain and mid- to rostral pons, one of which (ventral tegmental nucleus) is associated with the mammillary nuclei by way of the mammillary peduncle and mammillotegmental tract. Neurons in these nuclei are acetylcholinesterase rich. The anterior tegmental nucleus [TA], also called the ventral tegmental nucleus [TAalt] (nucleus tegmentalis anterior [TA]), is located in the pontine tegmentum adjacent to the medial longitudinal fasciculus at the level of the trigeminal motor nucleus. The posterior tegmental nucleus [TA], also called the dorsal tegmental nucleus [TAalt], is located in the rostral pons in the area of the central gray substance. The lateroposterior tegmental nucleus [TA], also known as the laterodorsal tegmental nucleus [TAalt] (nucleus tegmentalis posterolateralis [TA]), is a larger cell group located partially in the central gray and partially ventrolateral to it at rostral pontine levels. The pedunculopontine tegmental nucleus [TA] (nucleus tegmentalis pedunculopontinus [TA]) is located in the rostral pons and caudal midbrain and consists of a compact part [TA] (pars compacta [TA] or compact subnucleus [TAalt]) and a dissipated part [TA] (pars dissipata [TA] or dissipated subnucleus [TAalt]). SYN: Gudden tegmental nuclei, nuclei tegmenti.