What are the five special senses?
Vision, smell, taste, hearing and equilibrium (balance)
What are the two parts of the outer layer of the eye?
Sc
... [Show More] lera and cornea
What is included in the middle layer of the eye?
Choroid, the ciliary muscle and the iris.
The pupil is a hole in the ____.
Iris
The inner sensory layer is the _____.
Retina
What are the two types of photoreceptors and their functions?
The more numerous cells are rods which are stimulated in dim light. Rods are more sensitive to light but do not generate sharp or color images. The cones operate in bright light helping to generate sharp color images.
The interior of the eye (posterior to the lens) is filled with_____.
Vitreous fluid
True or False: The vision pathway begins as the optic tracts, crosses at the optic chiasm and then moves through the optic nerve.
False
Where is the LGN located?
Thalamus
True or False: The nasal visual field is the visual field on the lateral sides of each eye.
False
What allows for 3-D vision?
Overlapping information in the nasal visual fields allows for 3-D vision, called the binocular visual field.
True or false: Only the medial fibers cross at the optic chiasm.
True
The left side of the brain receives information from the _________ of the left eye and the ________ of the right eye.
The left side of the brain receives information from the medial side of the left eye and the lateral side of the right eye (bilateral right visual fields).
On a piece of paper, draw the visual pathway using two different colors. Note one comment below about what you learned about the vision pathway:
The medial rectus turns the eye _____. The medial rectus is controlled by CN _____.
Medially, CN III, oculomotor
Review all the extrinsic eye muscle locations.
What is a cataract?
Cataracts are lenses that slowly become hardened and cloudy over time.
What does diplopia mean?
Double vision
What is the purpose of the auricle?
The auricle (Figure 1) is shaped to funnel sound waves into the external acoustic canal so that sounds can be detected.
What is the purpose of cerumen?
Earwax which serves to trap foreign materials.
The inner end of the external acoustic meatus terminates at the _____.
Tympanic membrane
What bone touches the inner ear to transmit vibrations?
Stapes
The semicircular canals contribute in this way to the body's_____ sense.
Vestibular sense
The ______ is the sense organ for the auditory system.
Organ of Corti
The movement of the stereocilia stimulates the neurons to send impulses through the _____ nerve to the _______ lobe of the brain.
Cochlear nerve; temporal lobe.
What is unique about the way the auditory pathway travels to the brain?
The auditory pathway is a unique sensory pathway because the ascending pathways cross in addition to sending signals to the same side of the brain. The result is that sounds from each ear are equally interpreted on the left and right sides of the brain.
What is the difference between nerve deafness vs. conduction deafness?
Conduction deafness occurs from damage to the outer or middle ear structures. Nerve deafness occurs from damage to the nerve pathway.
Review all figures in the auditory and vestibular systems.
Olfactory nerves contain what type of receptor cells?
Bipolar receptor cells
The olfactory nerves travel through what bone?
Ethmoid (cribriform plate)
What is the order of the olfactory nerve pathway?
Olfactory nerves → olfactory bulbs → olfactory tracts→ temporal lobes
What is smell?
Smell is defined as a combination of a limited number of primary odors that are detectable by the brain.
Label all olfactory landmarks.
What is the anatomical word for taste?
Gustation (gustatory system)
True or false: The apex of the tongue is located on the anterior aspect of the mouth.
True
What is a bolus?
A compact mass of food, prepared by the tongue and teeth.
What type of papillae contain taste buds?
Circumvallate and fungiform papillae both contain taste buds
True or false: Gustatory cells are the chemoreceptors of the taste buds.
True
What is the purpose of basal cells?
Basal cells serve as stem cells, which divide and differentiate into new supporting cells which then form new gustatory cells.
True or false: The taste pathway sends signals via only one cranial nerve to the brain.
False (two nerves- facial and glossopharyngeal)
What is anosmia?
The loss of smell
Review all figures of the gustatory system.
medial rectus of eye
moves eye medially, controlling cranial nerve: 3 oculomotor
inferior rectus of eye
moves eye medially and depresses it, controlling cranial nerve: 3 oculomotor
superior rectus of eye
elevates eye and turns it medially, controlling cranial nerve: 3 occulomotor
inferior oblique of eye
elevates eye and turns it laterally, and external rotation. controlling cranial nerve: 3 occulomotor
superior oblique of eye
eye depression, lateral movement, and internal rotation, controlling cranial nerve: 4 trochlear nerve
lateral rectus of eye
moves eye laterally, controlling cranial nerve: 6 abducens
cataract
clouding and hardening of the lens of the eye, causing impairment of vision or blindness. Cataracts make vision look blurry because the light is unable to enter the lens clearly to be refracted onto the retina.
diplopia
double vision. Damage to the abducens nerve
ossicles of middle ear
malleus (hammer), incus (anvil), stapes (stirrup)
inner ear (labyrinth)
bony spaces within the temporal bone of the skull that contain the cochlea, the semicircular canals, and vestibule. The cochlea facilitates hearing. The semicircular canals and vestibule facilitate equilibrium and balance
conduction deafness
damage to the outer or middle ear structures. For example, a build up of cerumen can partially block sound waves entering the external acoustic meatus. Another cause of conduction deafness is if the ossicle bones fuse, decreasing the amount of vibrations transmitted to the inner ear
anosmia
loss of sense of smell
Ageusia
loss of the sensation of taste
seven primary odors
floral, musky, camphorous, pepperminty, etheral, pungent (stinging), putrid (rotten)
five primary tastes
sweet, sour, salty, bitter, umami
three types of papillae
filiform, fungiform, circumvallate
Papillae contain taste buds.
fungiform, circumvallate
gustatory cells
chemoreceptor cells inside the taste buds
basal cells of taste buds
serve as stem cells, which divide and differentiate into new supporting cells that then form new gustatory cells.
Innervation of the tongue: taste back 1/3
CN IX Glossopharyngeal
Innervation of the tongue: taste front 2/3, apex
CN VII Facial
Innervation of the tongue: general touch/pain back 1/3
CN IX Glossopharyngeal
Innervation of the tongue: general touch/pain front 2/3
CN V -- 3rd portion of Trigeminal
3 layers of the eye
external fibrous layer, middle vascular layer, inner sensory
external fibrous layer
scalera and cornea
Middle vascular layer of the eye
choroid, ciliary body, iris
internal (sensory) layer of the eye
Composed of retina. the retina consists of: rods and cones
Rods
retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don't respond
Cones
retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. The cones detect fine detail and give rise to color sensations.
One test for abducens nerve damage
have a person look left and right while keeping the head still. If the lateral rectus does not receive nervous signals from the abducens nerve, the eye is unable to rotate laterally when looking to the same side. The affected eye deviates medially when looking forward because of the imbalance in muscle tone between the medial and lateral recti.
The inner ear is composed of what?
bony and membranous labyrinths filled with fluid.
The bony labyrinth system is divided into three sections:
the vestibule, semicircular canals, and cochlea.
vestibule of ear
connects to three semicircular canals, which house receptors to provide the body's vestibular (equilibrium and balance) system.
stapedius muscle
Note that CNVII (facial nerve) is also located in the inner ear region. The facial nerve innervates a muscle called the stapedius, which is attached to the stapes. The stapedius controls the amount of tension on the bone, allowing for increased or decreased vibration to help control the intensity of sounds.
vestibular portion of CN VIII
Each semicircular canal contains equilibrium receptors, which cause action potentials in response to different types of motion (head movements or rotation). The action potentials are sent through the vestibular portion of CN VIII. The semicircular canals contribute in this way to the body's vestibular sense (balance and upright orientation)
cochlear portion of CN VIII
The mechanical movement of the stereocilia initiates an action potential in neurons that is transmitted through the cochlear nerve portion of CN VIII (Figure 3.11).
process of hearing in ear
The process of hearing happens in a series of events. First, sound waves are funneled into the external auditory canal causing the eardrum to vibrate. The vibrations transmit to the ossicles, which push against fluid inside the cochlear duct. The movement of the fluid causes movement of the stereocilia in the organ of Corti. The movement of the stereocilia then stimulates the neurons to send impulses through the cochlear nerve to the primary auditory cortex of the temporal lobe. The auditory pathway is a unique sensory pathway because the ascending pathways cross in addition to sending signals to the same side of the brain. The result is that sounds from each ear are equally interpreted on the left and right sides of the brain.
Conduction deafness is not complete because
Conduction deafness is not complete because the sound waves can be conducted through the cranial bones to move the organ of Corti. [Show Less]