Neuro Anatomy 2

• olfactory mucusa
• olfactory N
• olfactory bulbs
• olfactory tracts
• olfactory cortex

• in sphenoethmoid recess
• PSCC epithelium
• contains olfactory (bowman's) glands- secrete fluid
• olfactory cells-olfactory receptors, bipolar, constantly replaced, unmyelinated

• axons of olfactory cells
• enter cranial cavity thru cribiform foramina of ethmoid bone
• terminate in olfactory bulb as glomeruli

• extension of the brain
• made mainly of mitral cells- innervate glomeruli
• few tufted cells-also innervate glomeruli

• mostly mitral cells, few tufted
• most lead thru lateral olfactory stria, few to anterior perforated surface

• input thru lateral olfactory stria, makes primary olfactory area
• uncus- anterior parahippocampal gyrus)
• limen insula
• amygdala
• allows you to experience smells

• alows identification of odors
• adjacent to primary olfactory cortex

• between lateral and medial olfactory stria
• neurons connect to limbic structures
• not incolved in concious olfaction

• olfactory neurons project to areas of cerebral cortex, hypothalamus, and reticular system
• influence emotional and visceral status of an individual

• each nostil should be tested separately
• use recognizable odor
• non-irritative odor, otherwise you would be testing pain receptors

anosmia

• fractures of ethmoid bone
• meningioma in floor of anterior cranial fossa
• olfactory hallucinations

• convulsive movements of lips and tongue
• disagreable olfactory hallucinations
• confusion

• pinna- auricula
• external auditory meatus- bony
• external auditory canal- fleshy + bony
• collects air vibrations and transmits them to the tympanic membrane

• tympanic membrane
• malleus
• incus
• stapes
• oval window
• round window
• vibrations transferred thru ossicular chain to oval window

• tensor tympani (trigeminal N)
• stapedius (facial N)
• dampen loud noises/vibrations

• tunnels in the petris temporal bone
• filled with perilymph
• semicircular canals- posterior part
• vestibule- middle part
• cochlea- anterior part (2 ³/₄) turns

• membrane tubes in osseous labyrinth
• filled with enodlymph
• semicircular ducts- within semicircular canals
• utricle- connects to semicircular ducts
• saccule- connects to cochlear ducts via ductus reunions
• cochlear duct

• scala media- cochlear duct, middle space
• scala vestibuli-- superior to scala media, filled with perilymph, continuous with oval window
• scala tympani- inferior to scala media, filled with perilymph, continuous with scala vestibuli at helicotreme, continous with round window

• scala media
• vestibular membrane- b/t scala media and vestibuli
• stria vascularis- epithelial lining over vasculature, outer wall, produces endolymph
• basilar membrane- b/t scala media and tympani, includes organ of corti

• mechanoreceptor
• support cells- border cells, phalangeal cells, pillar cells, and cells of hensen
• tectorial membrane- gelatinous membrane along organ of corti, tips of hair cells embedded here
• sensory cells

• single row
• attached to chochlear nerve
• principal sensory cells

• three rows at basal turn increasing to five rows at apex
• innervated by chochlear nerve

• high pitch- along basal turn
• low pitch- apical end

• cell bodies in spiral ganglia
• peripheral processes innervate hair cells
• central processes make cochlear division of VIII N, terminate in cochlear nucleus

• cell bodies in cochlear nuclei
• processes project thru central auditory pathway

• axons project to contralateral side of pons
• -form the trapezoid body
• -some terminate in superior olivary nucleus
• -ascending fibers form lateral lemniscus, terminate in inferior colliculus, thru inferior brachium, into medial geniculate body of thalamus. axons thru internal capsule to form auditory radiations in primary auditory cortex

• secondary neurons in cochlear nucleus project to ipsilateral suprior olivary nucleus
• thru ipsilateral lateral lemnisculs, inferior colliculus, inferior brachium, medial geniculate body, and auditory radiations

• primary auditory cortex in floor of the lateral sulcus
• Heschl's gyrus- hears sounds, in transverse temporal gyrus
• brodmann's area 41, 42
• high hertz= medial
• low hertz= lateral

• temporal lobe surrounding heschl's gyrus
• brodmann's area 22
• recognition and interpretation of sounds

unilateral damage above cochlear nuclei results in decresed hearing in both ears, but not total loss of hearing

• maintain body equilibrium- posture and balance
• coordinate eye movements

• parts of membranous labyrinth filled with endolymph
• each contains a macula- sensory epithelium, mechanoreceptors

• hair cells- stereocilia projections with a single kinocilium embedded into the otolithic membrane
• otolithic membrane- gelatinous membrane with otolithes- crystals of protein and calcium carbonate
• dendrites of primary vestibular neurons- cell bodies in vestibular ganglion

tilting movements in a linear plane

vertical

30 degrees to the horizontal

• dilation at end of duct
• lateral semicircular duct has anterior ampulla
• contains crista ampullaris

• mechanoreceptor for angular/rotational movement
• hair cells- stereocilia with single kinocilium embedded in cupula
• vestibular neurons in vestibular gangion

flow toward the ampulla from the duct

flow away from the ampulla thru the duct

• ampullopedal movemnt facilitates crista
• ampullofugal movement inhibits crista

no net movement of endolymph so discharge returns to static rate

• major motor control pathway
• ipsilateral
• terminates on interneurons or motor neurons

• ipsilateral and contralateral (bilateral)
• most terminate in cervical segments to influence neck muscles

• permits visual fixation on stationary targets
• ipsilateral and contralateral
• influence cranial nerves VI, IV, and III
• allows both eyes to move together

• posture and balance
• neurons to vestibular nuclear complex, to vestibulospinal tract

• eyes slowly drift to the left (fixation on a target)- mediated by MLF
• eyes quickly move to the right (fixation on a new target)- not vestibular driven

fast-slow eye movements

• patient seated, head tilted forward 30 degrees, rotate at a constant velocity to the RIGHT
• continue until crista reach static discharge, stop chair and have patient stand and focus on stationary object
• eyes should display left nystagmus, patient will fall to the right, past point to the right of the object

• patient tilts head backwards 60 degrees
• irrigate external auditory meatus with warm or cool water
• response is COWS
• cool water= fast drift to opposite side
• warm water= fast drift to same side