spinal trigeminal nucleus

Examples of spinal trigeminal nucleus in the following topics:

• Vagus (X) Nerve

  • The dorsal nucleus of vagus nerve: Sends parasympathetic output to the viscera, especially the intestines.
  • The nucleus ambiguus: Sends parasympathetic output to the heart (slowing it down).
  • The solitary nucleus: Receives afferent taste information and primary afferents from visceral organs.
  • The spinal trigeminal nucleus: Receives information about deep/crude touch, pain, and temperature of the outer ear, the dura of the posterior cranial fossa, and the mucosa of the larynx.

• Medulla Oblongata

  • A stroke can injure the pyramidal tract, medial lemniscus, and the hypoglossal nucleus.
  • 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.
  • The gray matter of this nucleus is covered by a layer of nerve fibers that form the spinal tract of the trigeminal nerve.
  • The base of the medulla is defined by the commissural fibers, crossing over from the ipsilateral side in the spinal cord to the contralateral side in the brain stem; below this is the spinal cord.

• Trigeminal (V) Nerve

  • The trigeminal nerve is the largest of the cranial nerves.
  • Its name, trigeminal, means three twins.
  • The three branches converge on the trigeminal ganglion that is located within the trigeminal cave in the brain; it contains the cell bodies of incoming sensory nerve fibers.
  • The trigeminal ganglion is analogous to the dorsal root ganglia of the spinal cord, which contain the cell bodies of incoming sensory fibers from the rest of the body.
  • 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.

• Pons

  • Within the pons is the pneumotaxic center, a nucleus that regulates the change from inspiration to expiration.
  • The alar plate produces sensory neuroblasts, which will give rise to the solitary nucleus and its special visceral afferent column, the cochlear and vestibular nuclei (which form the special somatic afferent fibers of the vestibulocochlear nerve), the spinal and principal trigeminal nerve nuclei (which form the general somatic afferent column of the trigeminal nerve), and the pontine nuclei, which is involved in motor activity.
  • Basal plate neuroblasts give rise to the abducens nucleus (forms the general somatic efferent fibers), the facial and motor trigeminal nuclei (form the special visceral efferent column), and the superior salivatory nucleus, which forms the general visceral efferent fibers of the facial nerve.
  • The chief or pontine nucleus of the trigeminal nerve sensory nucleus (V)- mid-pons

• Parts of the Cerebellum

  • It receives proprioception input from the dorsal columns of the spinal cord (including the spinocerebellar tract) and from the trigeminal nerve, as well as from visual and auditory systems.
  • 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.

• General Organization of the Somatosensory System

  • The cell body of the primary neuron is housed in the dorsal root ganglion of a spinal nerve or, if sensation is in the head or neck, the ganglia of the trigeminal or cranial nerves.
  • The secondary neuron acts as a relay and is located in either the spinal cord or the brainstem.
  • This neuron's ascending axons will cross, or decussate, to the opposite side of the spinal cord or brainstem and travel up the spinal cord to the brain, where most will terminate in either the thalamus or the cerebellum.
  • The somatosensory system functions in the body’s periphery, spinal cord, and the brain.
  • Spinal cord: Afferent pathways in the spinal cord serve to pass information from the periphery and the rest of the body to the brain.

• Brief Overview of Cranial Nerves

  • In contrast, spinal nerves emerge from segments of the spinal cord.
  • Spinal nerves emerge sequentially from the spinal cord with the spinal nerve closest to the head (C1) emerging in the space above the first cervical vertebra.
  • The trigeminal nerve (V): This is responsible for sensation and motor function in the face and mouth.
  • The spinal accessory (XI): This nerve controls specific muscles of the shoulder and neck.

• Spinal Cord White Matter

  • The white matter of the spinal cord is composed of bundles of myelinated axons.
  • Projection tracts extend vertically between higher and lower brain and spinal cord centers.
  • The cortico spinal tracts, for example, carry motor signals from the cerebrum to the brainstem and spinal cord.
  • The cerebellum is structured in a similar manner as the cerebrum, with a superficial mantle of cerebellar cortex, deep cerebellar white matter (called the "arbor vitae") and aggregates of grey matter surrounded by deep cerebellar white matter (dentate nucleus, globose nucleus, emboliform nucleus, and fastigial nucleus).
  • The spinal cord diagram showing location of the white matter surrounding grey matter.

• Oculomotor (III) Nerve

  • The oculomotor nucleus originates at the level of the superior colliculus.
  • 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.

• Subdivisions of the Nervous System

  • The CNS includes the brain and spinal cord, while the PNS is a network of nerves linking the body to the brain and spinal cord.
  • White matter includes all of the nerves of the PNS and much of the interior of the brain and spinal cord.
  • By convention, a cluster of neuron cell bodies in the gray matter of the brain or spinal cord is called a nucleus, whereas a cluster of neuron cell bodies in the periphery is called a ganglion.
  • The central nervous system (2) is a combination of the brain (1) and the spinal cord (3).
  • The brain and the spinal cord are the central nervous system (CNS) (shown in yellow).