Bio 168 special senses
Rods
110-130 million, function in dim light and peripheral vision, distributed throughout retina. Multiple rods synapse with a single bipolar cell, which synapse with a single ganglion
Cones
5-7 million, function in bright light, color vision, greatest concentration in fovea central. Usually synapse with single bipolar cell, which synapses with a single ganglion
Gustatory pathway
Anterior 2/3 transmitted to CN VII facial; posterior 1/3 transmitted to CN IX glossopharyngeal
Middle ear
Auditory ossicles: malleus, incus and stapes. Pharyngotympanic tube
Scala tympani
Bottom opening in cochlea, terminates at round window
Internal ear
Cochlea, semicircular canals, vestibule
Scala media
Cochlear duct
Iris
Colored portion of eye, contains circular and radial muscles that regulate size of pupil
Retina- neural layer
Consists of rods and cones, lines posterior chamber of eye
Ciliary body
Controls shape of lens
Diplopia
Double vision
Orbicularis oculi m.
Encircles eye
Anterior segment
Includes anterior chamber and posterior chamber, aqueous humor
Optic disc
Lacks photoreceptors, blond spot
Posterior segment
Larger segment filled with vitreous humor
Vallate
Largest and least numerous, back of tongue
Maculae
Linear speed and direction, within vestibule of inner ear
Vision
Most important 70% of sensory receptirs, nearly half of cerebral cortex involved
Filiform
Most numerous, lack taste buds
Fungiform
Mushroom-shaped, throughout the tongue
Retina- pigmented layer
Pigment absorbs light to prevent light from scattering within eye
External ear
Pinna, external acoustic meatus, and tympanic membrane
Olfactory epithelium
Pseudo stratified epithelium, roof of nasal cavity. CN I
Close vision/bright light
Pupil constricts to reduce amount of light entering eye
Dim light/ distant vision
Pupil opens to allow more light to enter
Lacrimal gland
Releases dilute saline solution; contains mucus, antibodies and lysozyme
Foliate
Ridges along lateral sides of tongue
Superior oblique
Rotates eye downwards and laterally; CN IV tendon passes through trochlea
Inferior rectus
Rotates eye downwards and medially; CN III
Lateral rectus
Rotates eye laterally; CN VI
Medial rectus
Rotates eye medially; CN III
Inferior oblique
Rotates eye upwards and laterally; CN III
Superior rectus
Rotates eye upwards and medially; CN III
Basilar membrane
Separates Scala tympani from cochlear duct, associated with spiral organ
Vestibular membrane
Separates Scala vestibui from cochlear duct
Tarsal plates
Supportive CT sheets within eyelids
Otoliths
Tiny deposits of calcium carbonate that increase the weight of the membrane
Scala vestibuli
Top opening in cochlea, receives vibrations via oval window
Cornea
Transparent, innervated but avascular
Choroid
Vascular and pigmented
Sclera
Whites of yes
