trigeminal nerve

Examples of trigeminal nerve in the following topics:

• Trigeminal (V) Nerve

  • The trigeminal nerve is the fifth cranial nerve and it is responsible for sensation and motor function in the face and mouth.
  • The trigeminal nerve (cranial nerve V), and it contains both sensory and motor fibers.
  • The trigeminal nerve is the largest of the cranial nerves.
  • 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.
  • 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

  • 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.
  • A number of cranial nerve nuclei are present in the pons:
  • The chief or pontine nucleus of the trigeminal nerve sensory nucleus (V)- mid-pons
  • The functions of the four nerves of the pons include sensory roles in hearing, equilibrium, taste, and facial sensations such as touch and pain.

• Temporomandibular Joint Syndrome (TMJ)

  • On average, the symptoms will involve more than one of the numerous TMJ components: muscles, nerves, tendons, ligaments, bones, connective tissue, and the teeth.
  • The pain, therefore, originates from one of the surrounding soft tissues, or from the trigeminal nerve itself, which runs through the joint area.
  • However, inflammation of the joints or damage to the trigeminal nerve can cause constant pain, even without movement of the jaw.

• Oculomotor (III) Nerve

  • The oculomoter nerve (cranial nerve III) controls eye movement, such as constriction of the pupil and open eyelids.
  • The oculomotor nerve is the third paired cranial nerve.
  • 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.
  • Here the nerve is placed below the trochlear nerve and the frontal and lacrimal branches of the ophthalmic nerve, while the nasociliary nerve is placed between its two rami (the superior and inferior branch of oculomotor nerve).
  • Image of cranial nerves showing the position of the oculomotor nerve.

• Brief Overview of Cranial Nerves

  • Cranial nerves are the nerves that emerge directly from the brain (including the brainstem).
  • The terminal nerves, olfactory nerves (I) and optic nerves (II) emerge from the cerebrum or forebrain, and the remaining ten pairs arise from the brainstem, which is the lower part of the brain.
  • The optic nerve (II): This nerve carries visual information from the retina of the eye to the brain.
  • The trigeminal nerve (V): This is responsible for sensation and motor function in the face and mouth.
  • The hypoglossal nerve (XII): This nerve controls the tongue movements of speech, food manipulation, and swallowing.

• Facial (VII) Nerve

  • The facial nerve (cranial nerve VII) determines facial expressions and the taste sensations of the tongue.
  • The facial nerve is the seventh (cranial nerve VII) of the 12, paired cranial nerves.
  • 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.
  • In regards to the corneal reflex, the afferent arc is mediated by the general sensory afferents of the trigeminal nerve.
  • The efferent arc occurs via the facial nerve.

• Medulla Oblongata

  • 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.

• 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.

• Postganglionic Neurons

  • Presynaptic nerves' axons terminate in either the paravertebral ganglia or prevertebral ganglia.
  • In all cases, the axon enters the paravertebral ganglion at the level of its originating spinal nerve.
  • As a result, the postsynaptic parasympathetic nerve fibers are very short.
  • From these four ganglia the postsynaptic fibers complete their journey to target tissues via Cranial nerve V (trigeminal) (ophthalmic, maxillary, mandibular branches ).
  • The postganglionic nerve then releases ACh to stimulate the muscarinic receptors of the target organ.

• Vagus (X) Nerve

  • The vagus nerve (cranial nerve X) is responsible for parasympathetic output to the heart and visceral organs.
  • The vagus nerve, also known as the pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves.
  • Eighty to 90% of the nerve fibers in the vagus nerve are afferent (sensory) nerves that communicate the state of the viscera to the brain.
  • The vagus nerve includes axons that emerge from or converge onto four nuclei of the medulla.
  • 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.