medial geniculate nucleus

Examples of medial geniculate nucleus in the following topics:

• Thalamus

  • The thalamus derives its blood supply from four arteries including the polar artery (posterior communicating artery), paramedian thalamic-subthalamic arteries, inferolateral (thalamogeniculate) arteries, and posterior (medial and lateral) choroidal arteries.
  • In particular, every sensory system (with the exception of the olfactory system) has a thalamic nucleus that receives sensory signals and sends them to the associated primary cortical area.
  • For the visual system, for example, inputs from the retina are sent to the lateral geniculate nucleus of the thalamus, which in turn projects to the primary visual cortex in the occipital lobe.
  • Similarly, the medial geniculate nucleus acts as a key auditory relay between the inferior colliculus of the midbrain and the primary auditory cortex.
  • The ventral posterior nucleus is a key somatosensory relay, which sends touch and proprioceptive information to the primary somatosensory cortex.

• Facial (VII) Nerve

  • The motor part of the facial nerve arises from the facial nerve nucleus in the pons, while the sensory part of the facial nerve arises from the nervus intermedius.
  • The facial nerve forms the geniculate ganglion prior to entering the facial canal.

• Optic (II) Nerve

  • Most of the axons of the optic nerve terminate in the lateral geniculate nucleus (where information is relayed to the visual cortex), while other axons terminate in the pretectal nucleus and are involved in reflexive eye movements.

• Hypothalamus

  • The extreme lateral part of the ventromedial nucleus of the hypothalamus is responsible for control of food intake.
  • Medial parts of the nucleus have a controlling effect on the lateral part.
  • Bilateral lesion of the medial part of the ventromedial nucleus causes hyperphagia and obesity.
  • The medial zone of hypothalamus is part of a circuitry that controls motivated behaviors, such as defensive behaviors and social defeat.
  • Nuclei in the medial zone are also mobilized during an encounter with an aggressor.

• Medulla Oblongata

  • A stroke can injure the pyramidal tract, medial lemniscus, and the hypoglossal nucleus.
  • This causes a syndrome called medial medullary syndrome, a type of alternating hemiplegia characterized by recurrent episodes of paralysis on one side of the body.
  • These are the fasciculus gracilis, lying medially next to the midline, and the fasciculus cuneatus, lying laterally.
  • They are caused by masses of gray matter known as the nucleus gracilis and the nucleus cuneatus.
  • It is caused by an underlying collection of gray matter known as the spinal nucleus of the trigeminal nerve.

• Reticular Formation

  • The raphe nuclei form a ridge in the middle of the reticular formation, and directly to its periphery, there is a division called the medial reticular formation.
  • The medial reticular formation is large, has long ascending and descending fibers, and is surrounded by the lateral reticular formation.
  • The medial reticular formation and lateral reticular formation are two columns of neuronal nuclei with ill-defined boundaries that send projections through the medulla and into the mesencephalon (midbrain).
  • The magnocellular red nucleus is involved in motor coordination, and the parvocellular nucleus regulates exhalation.

• Parts of the Cerebellum

  • Excluding the flocculonodular lobe, which has distinct connections and functions, the cerebellum can be parsed functionally into a medial sector called the spinocerebellum and a larger lateral sector called the cerebrocerebellum.
  • The medial zone of the anterior and posterior lobes constitutes the spinocerebellum, also known as the paleocerebellum.
  • It receives input exclusively from the cerebral cortex (especially the parietal lobe) via the pontine nuclei (forming corticopontocerebellar pathways), and sends output mainly to the ventrolateral thalamus (in turn connected to motor areas of the premotor cortex and primary motor area of the cerebral cortex) and to the red nucleus.

• Functions of the Diencephalon

  • In particular, every sensory system (with the exception of the olfactory system) includes a thalamic nucleus that receives sensory signals and sends them to the associated primary cortical area.
  • The subthalamus connects to the globus pallidus, a basal nucleus of the telencephalon.

• Trigeminal (V) Nerve

  • Motor fibers pass through the trigeminal ganglion on their way to peripheral muscles, but their cell bodies are located in the nucleus of the trigeminal nerve, deep within the pons.
  • The motor component of the mandibular division (V3) of the trigeminal nerve controls the movement of eight muscles, including the four muscles of mastication: the masseter, the temporal, and the medial and lateral pterygoids.

• Somatic Sensory Pathways

  • In the case of touch and certain types of pain, the third neuron has its cell body in the ventral posterior nucleus of the thalamus and ends in the postcentral gyrus of the parietal lobe.
  • This is the target for neurons of the dorsal column–medial lemniscal pathway and the ventral spinothalamic pathway.