The cochlear and vestibular nuclei sit dorsolaterally from the inferior pons to the superior medulla.Ĭlinical Relevance – Cerebellopontine Angle Syndrome Its fibres take an unusual course and loop around the abducens nucleus before exiting the brainstem through its ventrolateral surface. It controls the muscles of facial expression. It is located in the caudal pons, on the medial aspect of its dorsal surface.Īt the same level of the abducens nucleus, the facial nucleus is located more anteriorly and laterally. The abducens nucleus controls the abducens nerve, which innervates the ipsilateral lateral rectus muscle. Mesencephalic nucleus – extends rostrally all the way to the midbrain.Spinal trigeminal nucleus – extends caudally towards the medulla.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. ![]()
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