Taste & Smell Flashcards
Location of taste buds
mostly on fungiform and circumvallate/vallate papillae
also on foliate papillae, palate (posterior), epiglottis
SA of tongue
VII to anterior 2/3 of tongue and soft palate
IX to posterior 1/3 of tongue
X to epiglottis
GSA/GVA of tongue
GSA: V Anterior 2/3 of tongue, hard and soft palate
GVA: IX posterior 1/3 of tongue, palatine tonsils, pharynx
GVA: X epiglottis
Firing of taste receptor cell
molecule activates taste receptor cell
depol of cell
increase intracellular Ca via VG-Ca channels
release NT
transmit signal to CNS to nucleus solitarius
Taste pathway (4) ipsilateral or contralateral?
1) CN VII, IX, or X to nucleus solitarius
- central tegmental tract
2) VPM (ventral posteromedial nucleus)
- posterior limb of internal capsule
3) gustatory cortex
IPSILATERAL
Gustatory cortex location
- in insula and medial surface of frontal operculum
- in depths of lateral sulcus near base of central sulcus
CN I special feature
only sensory system with no precortical relay to thalmus. (goes to cortex before thalmus)
Olfactory epithelium
- pseudostratified columnar
- bipolar
- olfactory receptor cells (neurons), basal cells and support cells
- bowman’s mucus producing glands
- replaced 1-2 months
Location of olfractory receptors
unmyelinated neurons form olfactory filia bundles through cribiform plate, non-motile cilia with odorant receptors extend into mucus layer
Where does CN I leave brainstem, reside in skull and where does it exit?
- does not join brainstem
- in anterior cranial fossa
- exit via cribiform plate in ethmoid bone
Olfactory tract fibers terminate in (4)
ipsilateral or contralateral termination?
from olfactory bulb:
- anterior olfactory nucleus (contralateral)
- olfactory tubercle (ipsilateral)
- amygdala (ipsilateral)
- primary olfactory cortex (ipsilateral)
Tract to anterior olfactory nucleus
-cross to side via anterior commisure, to contralateral olfactory bulb
Primary olfactory cortex
location, components
- in uncus of temporal lobe
- composed of:
- piriform cortex (adjacent to lateral olf tract)
- periamygdaloid cortex
- anterior parahippocampal gyrus
Primary olfactory cortex projects to:
- thalamus (dorsomedial nucleus): after afferents reach primary olf cortex but before association cortex/orbitofrontal cortex
- hippocampus: learning/feeding
- hypothalamus: feeding behaviors
Integration/Convergence
- gustatory, somatosensory, olfactory, visual cortical areas, amygdala project to ORBITOFRONTAL CORTEX
- involved in perception of flavour
