The pontine tegmentum, or dorsal pons, is located within the brainstem, and is one of two parts of the pons, the other being the ventral pons or basilar part of the pons. The pontine tegmentum can be defined in contrast to the basilar pons: basilar pons contains the corticospinal tract running craniocaudally and can be considered the rostral extension of the ventral medulla oblongata; however, basilar pons is distinguished from ventral medulla oblongata in that it contains additional transverse pontine fibres that continue laterally to become the middle cerebellar peduncle. The pontine tegmentum is all the material dorsal from the basilar pons to the fourth ventricle. Along with the dorsal surface of the medulla, it forms part of the rhomboid fossa – the floor of the fourth ventricle. The pontine tegmentum contains nuclei of the cranial nerves (trigeminal (5th), abducens (6th), facial (7th), and vestibulocochlear (8th) cranial nerve nuclei) and their associated fibre tracts, the tegmental pontine reticular nucleus, the mesopontine cholinergic system comprising the pedunculopontine nucleus and the laterodorsal tegmental nucleus, and in the respiratory center the pontine respiratory group – the pneumotaxic centre and the apneustic centre. Nearby important structures include the cranial nerve nuclei of the oculomotor (3rd) and trochlear (4th) nerve nuclei, which are located in the midbrain, the pontine nuclei, which are located within the basilar pons, and the raphe nucleus and the locus ceruleus, nuclei of cranial nerves 9-12, and the dorsal respiratory group, which are located further caudally in the brainstem. The dorsal respiratory group are connected to the pneumotaxic and apneustic centres of the pontine tegmentum. Function Thanks to the number of different nuclei located within the pontine tegmentum, it is a region associated with a range of functions including sensory and motor functions (due to the cranial nuclei and fiber tracts), control of stages of sleep and levels of arousal and vigilance (due to the ascending cholinergic systems), and some aspects of respiratory control. Functions of the cranial nerve nuclei The pontine tegmentum contains nuclei of several cranial nerves and consequently has a role in several groups of sensory and motor processes. The principal sensory nucleus of the trigeminal nerve represents touch and position information of the head and face, but not the neck or back of the head, which are innervated by the cervical nerves. Pain and temperature information is also not represented within the principle nucleus, but rather in