16-general sensory pathways of the face area, taste ......the vestibular nuclei/pathway •location...
TRANSCRIPT
General Sensory Pathways of the Face Area, Taste Pathways
and Hearing Pathways
Lecture Objectives
• Describe pathways for general sensations (pain, temperature, touch and proprioception) from the face area.
• Describe taste pathways.• Describe hearing pathways.
Sensory Innervation of Head
• Most of the sensory innervation of the head region is supplied by some cranial nerves • Trigeminal, facial, glossopharyngeal & vagus
• Spinal nerves (C1‐C3) participate in the sensory innervation of the head
Cranial Nerves Innervating Head
Sensory Innervation: Modalities and Territories
Trigeminal nerve (V)
• GSA Trigeminal ganglion• Skin of face and head• Mucus membrane
• Nasal cavity• Oral cavity• Paranasal sinuses
• Eye • External ear• Dura matter• TMJ• Teeth
Facial Nerve (VII)
Geniculate ganglion• GSA
• External ear & mastoid
• SVA • Taste from tongue (anterior ⅔)
• GVA • Soft palate • Floor of the mouth• Pharynx
Glossopharyngeal Nerve (IX)
• GSA• External earSuperior ganglion
• SVA • Taste from tongue (posterior ⅓) Inferior ganglion
• GVA • Tongue (posterior ⅓)• Fauces• Pharynx• Middle ear• Carotid sinus baroreceptors• Carotid body chemoreceptors Inferior ganglion
Vagus Nerve (X)• GSA
• External earSuperior jagular ganglion
• SVA • Taste (epiglottis & base of tongue)Inferior nodose ganglion
• GVA• Pharynx• Larynx• Other visceraInferior nodose ganglion
Sensory Innervation of HeadSummary
• Trigeminal nerve • GSA
• Skin of face and head• Mucus membrane
• Facial nerve• GSA – external ear & mastoid• SVA – taste from tongue (anterior ⅔)• GVA – soft palate , floor of the mouth, pharynx
• Glossopharyngeal nerve• GSA – external ear• SVA – taste from tongue (posterior ⅓)• GVA – tongue (posterior ⅓), fauces, pharynx, middle ear
• Vagus nerve• GSA – external ear• SVA – taste (epiglottis & base of tongue)• GVA – pharynx, larynx, other viscera
• Spinal nerves (C2‐C3) • GSA – scalp & dura mater
Sensory Innervation of HeadSummary
• 1st order neurons• Trigeminal nerve
• Trigeminal ganglion (V) – GSA • Facial nerve
• Geniculate ganglion (VII) – GSA, GVA, SVA• Glossopharyngeal nerve
• Superior ganglion (IX) – GSA • Inferior ganglion (IX) – SVA, GVA
• Vagus nerve• Superior jugular ganglion (V) – GSA • Inferior nodose ganglion (V) – GVA, SVA
• Spinal nerves• Dorsal root ganglion (C1‐C3)
Cranial Nerve Innervating Head
Central Sensory Component
Brainstem Sensory Nuclei
• Nucleus of tractus solitarius(GVA, SVA)
• Trigeminal sensory complex (GSA)• Spinal nucleus• Main sensory nucleus• Mesencephalic nucleus
Nucleus of Tractus Solitarius
• GVA, SVA• Sensory nucleus for
• Facial nerve• Glossopharyngeal nerve• Vagus nerve
• Contains 2nd order neurons• Axons cross midline
• 3rd order neuron – PVM of thalamus• Axons → internal capsule → corona radiata→ cortex (postcentral gyrus)
Facial Nerve
Glossopharyngeal Nerve
Vagus Nerve
Trigeminal System
• Most of the sensory information from head are carried by the trigeminal nerve• Face, oral & nasal cavities, cornea, meninges and cranial blood vessels
• Small sensory components (GSA) of cranial nerve VII, IX, X• All GSA information is processed by trigeminal nuclei
Trigeminal Nerve Sensory Nuclei• Mesencephalic nucleus (GSA)
• Unconscious proprioception • Location, Extension
• Main sensory nucleus (GSA)• Touch & pressure
• Spinal nucleus* (GSA)• Pain & temperature• Extensions
• Medulla – C2• Somatotopic organisation
• Ophthalmic – most caudal• Mandibular – most rostral
*receive GSA from V, IX, X
Trigeminal Nerve Sensory Nuclei• Spinal nucleus parts
• Pars caudalisBelow pyramidal decussation• Pain & temperature• Receive fibers from: C1‐C3, GSA from IIV, IX, V, cerebral blood vessels
• Pars interpolarisBelow rostral third of the inferior olivarynucleus
• Pain sensation from teeth• Light touch
• Pars oralis• Light touch• Discriminative touch
• Main sensory nucleus• Light touch• Discriminative touch
Trigeminal Nerve Sensory Nuclei• 1st order neurons
• Trigeminal ganglion• 2nd order neurons
• Trigeminal nerve sensory nuclei
• Except mesencephalicnucleus• Contains 1st order neurons
• Central axons cross midline• Form trigeminal lemniscus
• 3rd order neurons • VPM nucleus of thalamus• Internal capsule
Trigemino‐cervical Complex
• Upper cervical afferents converge to the pars caudalis of spinal trigeminal nucleus
• Cervical headache (cervicogenicheadache)• Pain referred from cervical origin to the head structures
Trigemino‐vascular system
• Cerebral vessels and meningeal vessels are innervated by trigeminal nerve
• Pain afferents converge to the spinal trigeminal nucleus
• Migraine
Vestibulocochlear Nerve (VIII)• Formerly called the acoustic or auditory nerve
• Brainstem (between pons & medulla) → Internal acoustic meatus
• Mainly a sensory nerve
• Consists of two branches:
Cochlear branch• Associated with hearing• Receptors in the spiral organ in the cochlea • The cell bodies in the spiral ganglion• Axons travel to nuclei in the medulla• if damaged deafness or tinnitus (ringing) is
produced
Auditory Nuclei/Pathway• 1st order neuron – spiral ganglion• 2nd order neurons
• Cochlear nuclei• Anterior & posterior
• Location• Relations – inferior cerebellar
peduncles• Axons cross and uncross midline
• 3rd order neurons • Posterior nucleus of trapezoid body & superior olivary nucleus
• Axons – lateral lemniscus• 4th order neurons
• Inferior colliculus• Medial geniculate body (5th) → internal capsule → auditory cortex (superior temporal gyrus)
Vestibulocochlear Nerve (VIII)
Vestibular branch• Associated with equilibrium• Receptors in the semicircular canals, saccule, and utricle
• The cell bodies in vestibular ganglion
• Axons travel to nuclei in the thalamus; some fibers also travel to the cerebellum
• Lesion results in disequilibrium, vertigo, nystagmus, ataxia
The Vestibular Nuclei/Pathway
• Location – 4th ventricle• Vestibular nuclei (2nd order neurons)• Lateral → vistibulospinal tract• Superior• Medial• Inferior
• Inputs from cerebellum• Axons To spinal cordTo eye muscles nerves (III, IV, VI)To thalamus (VP) → vestibular area in cerebral cortex (postcentral gyrus)