There are two other nuclei that receive sensory information from the trigeminal nerve: The main sensory nucleus receives somatosensory information from the face. The main sensory nucleus and the trigeminal motor nucleus are located in the midpons – at the level where the fibres originate from the lateral aspect of the pons. The pons houses important cranial nerve nuclei. Ascending spinothalamic tracts – responsible for pain and temperature sensation.Ascending medial lemniscus tracts – responsible for fine touch, vibration and proprioception.Descending corticobulbar tracts – responsible for voluntary motor control of face, head and neck.Descending corticospinal tracts – responsible for voluntary motor control of the body.The rest of the pons is made up of tracts passing through the pons including: Damage to this part of the pons may result in anosognosia for hemiplegia, where patients are unaware of their paralysis. The tegmentum is the evolutionarily older part of the pons which forms part of the reticular formation – a set of nuclei found throughout the brainstem that are responsible for arousal and attentiveness. Fibres from the pontine nuclei cross the midline and form the middle cerebellar peduncles on their way to the cerebellum. The ventral pons contains the pontine nuclei, which are responsible for coordinating movement. The pons is comprised of two major components – the ventral pons and the tegmentum. Here, the cerebellar flocculus, the ventricular choroid plexus and the emerging CNs VII and VIII surround the lateral apertures of the fourth ventricle (the foramen of Luschka). The angle formed at the junction of the pons, medulla, and cerebellum is another anatomical landmark and is named cerebellopontine angle. They mark the posterior border between the pons and the medulla. The stria medullaris of the fourth ventricle is a bundle of nerve fibres crossing transversely from the lateral aspect into the midline.The facial colliculus is a bulging formed by the fibres of the facial nerve looping around the abducens nucleus.The medial eminence marks the midline of the floor.There are some important anatomical landmarks here: The floor of the fourth ventricle is composed of the dorsal surface of the pons and the medulla. Removal of the cerebellum will reveal the underlying fourth ventricle. The pons is intimately related to the cerebellum and is connected to it by the middle cerebellar peduncles. Fig 2 – Ventral (anterior) surface of the pons.
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