Vestibular System – Cranial Nerve VIII PDF

Vestibular System – Cranial Nerve VIII Jean Marie Berliner, PT, DPT, PhD, NCS Neuroscience By the end of this session, the student will be able to: 1. 2. 3. Objectives 4. 5. 6. 7. 8. Understand and describe the basic ascending auditory pathway describe the three primary roles of the vestibular syste...

Vestibular System – Cranial Nerve VIII Jean Marie Berliner, PT, DPT, PhD, NCS Neuroscience By the end of this session, the student will be able to: 1. 2. 3. Objectives 4. 5. 6. 7. 8. Understand and describe the basic ascending auditory pathway describe the three primary roles of the vestibular system describe the components and functions of the peripheral vestibular receptor describe the course and location of the vestibular nerve and ganglion describe the location and function of the four primary vestibular nuclei identify major output and input pathways to the vestibular nuclei identify vascular supply to the vestibular receptor and nuclei explain the neural basis and significance of nystagmus The Auditory Pathway Starts at the cochlear nuclei Then to the superior olivary complex Inferior colliculus Medial geniculate nucleus Then projected to the auditory cortex. The Auditory Pathway https://youtu.be/1mcbqJtuqRU 4 Vestibular System 3 1 2 4 Vestibular System: 3-fold role 1 2 3: to provide conscious awareness of spatial orientation The sensory receptor – Hair Cell Semicircular canals Orientation of the Semicircular Canals Function of semi-circular canals Otolithic organs Utricle and saccule structure – the macula Benign Paroxysmal Positional Vertigo (BPPV) The vestibular nerve Vestibular nuclei Vestibulo-occular reflex Excitatory connections: red Inhibitory connections: black VOR Testing Nystagmus Defined by rhythmic, abnormal eye movements with a ”slow” phase driving the eye off a target followed by a second movement ”fast” phase that brings the eye back to the target. The movement can be horizontal, vertical, torsional, or a combination of these movements. Nystagmus Nystagmus Physiologic nystagmus: characteristic of normal oculomotor function (end range, optokinetic nystagmus, VOR, caloric nystagmus, and rotary nystagmus, etc. ) Pathological nystagmus: abnormal nystagmus from central or peripheral nervous system damage (vestibular hypofunction, central nervous system damage, positional nystagmus (BPPV), medication induces nystagmus) Optokinetic nystagmus Vestibulo-spinal reflex Vestibulo-collic reflex Break up into 2-3 students and answer the following question: Break up into 2-3 students and answer the following question: What is the purpose of vestibulo-ocular reflexes? Break up into 2-3 students and answer the following question: What vestibular organ is active (which side is hyperpolarizing and which side is depolarizing) during moving your head in left/right rotation? How about while on an elevator? How about on a train going in a straight direction?