lateral geniculate nucleus

Examples of lateral geniculate nucleus in the following topics:

• 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.

• 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.

• Oculomotor (III) Nerve

  • The oculomotor nucleus originates at the level of the superior colliculus.
  • The muscles it controls are the striated muscle in the levator palpebrae superioris and all extraocular muscles, except for the superior oblique muscle and the lateral rectus muscle.
  • The Edinger-Westphal nucleus supplies parasympathetic fibers to the eye via the ciliary ganglion, and controls the pupillae muscle (affecting pupil constriction) and the ciliary muscle (affecting accommodation).
  • It then runs along the lateral wall of the cavernous sinus, above the other orbital nerves, receiving in its course one or two filaments from the cavernous plexus of the sympathetic nervous system, and a communicating branch from the ophthalmic division of the trigeminal nerve.
  • It then divides into two branches that enter the orbit through the superior orbital fissure, between the two heads of the lateral rectus (a muscle on the lateral side of the eyeball in the orbit).

• Cartilaginous Joints: Symphyses

  • The discs consist of an outer annulus fibrosus that surrounds the inner nucleus pulposus.
  • The annulus fibrosus and the nucleus pulposus distribute pressure evenly across the disc.
  • The nucleus pulposus contains loose fibers suspended in a mucoprotein gel with the consistency of jelly.
  • The disc can be likened to a jelly doughnut with the annulus fibrosis as the dough and the nucleus pulposis as the jelly.
  • The lateral and superior view of an invertebral disc, including the vertebral body, intervertebral foramen, anulus fibrosis, and nucleus pulposus.

• Medulla Oblongata

  • A stroke can injure the pyramidal tract, medial lemniscus, and the hypoglossal nucleus.
  • 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.
  • The lower part of the medulla, immediately lateral to the fasciculus cuneatus, is marked by another longitudinal elevation known as the tuberculum cinereum.
  • It is caused by an underlying collection of gray matter known as the spinal nucleus of the trigeminal nerve.

• 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.
  • Further lesion of the lateral part of the ventromedial nucleus in the same animal produces complete cessation of food intake.
  • Some differences are apparent even in gross neuroanatomy, most notably is the sexually dimorphic nucleus within the preoptic area.

• Somatic Sensory Pathways to the Cerebellum

  • There it makes a synapse with the dendrites of two neurons that send their axons bilaterally to the ventral border of the lateral funiculi (transmit the contralateral corticospinal and spinothalamic tracts).
  • This is in contrast with the dorsal spinocerebellar tract (C8 - L2/L3), which only has one unilateral axon that has its cell body in Clarke's nucleus (only at the level of C8 - L2/L3).
  • Axons first cross midline in the spinal cord and run in the ventral border of the lateral funiculi.
  • These central processes travel through the dorsal horn where they synapse with second order neurons of Clarke's nucleus.
  • Axon fibers from Clarke's nucleus convey this proprioceptive information in the spinal cord to the peripheral region of the posterolateral funiculus ipsilaterally until it reaches the cerebellum, where unconscious proprioceptive information is processed.

• Reticular Formation

  • The medial reticular formation is large, has long ascending and descending fibers, and is surrounded by the lateral reticular formation.
  • The lateral reticular formation is close to the motor nuclei of the cranial nerves and mostly mediates their function.
  • 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.

• The Posterior Pituitary

  • The posterior pituitary stores two hormones secreted by the hypothalamus for later release:
  • Oxytocin, most of which is released from the paraventricular nucleus in the hypothalamus.
  • Antidiuretic hormone (ADH, also known as vasopressin), the majority of which is released from the supraoptic nucleus in the hypothalamus.