Module 3 Flashcards
What are the Special Senses?
- Vision
- Smell
- Taste
- Hearing
- Equilibrium
What are the 2 parts of the outer eye?
- Sclera
- Cornea
Sclera
- Posterior portion
- “white of the eye”
Cornea
- Anterior portion
- Transparent part of eye
- Where light enters
Aqueous Humor
A clear fluid that fills the space between the cornea and the lens
What is included in the middle layer of the eye?
- Choroid
- Ciliary Body
- Iris
Choroid (4)
- Darkly-colored, posterior portion
- Prevents light from dispersing throughout the eye
- Highly vascular
- Supplies blood to the layers of the eye
Ciliary Body
- Anterior
- Muscles that attach to the lens to change the shape which allows it to focus
Iris
- Anterior to ciliary body
- Controls amount of light that enters pupil by using muscle fibers to contract or dilate based on environmental light
Pupil
Hole in the center of the iris
Lens
- Posterior to iris and pupil
- Circular ciliary muscles attach all the way around the lens
What is the inner (sensory) layer of the eye anatomy?
Retina
Retina
Contains photoreceptors; rods & cones
Rods
Sensitive to dim light, do not generate sharp or color images
Cones
Operate in bright light, help detect color images
What is the interior of the eye anatomy?
Vitreous Body
Vitreous Body
- Posterior to lens
- Chamber filled w/ vitreous fluid, helps to hold the retina firmly to choroid
Nasal Visual Fields
- Left & right eyes
- Closest to nose
- Overlapping visual fields allows for 3D vision (binocular)
Peripheral Visual Fields
Lateral side of each eye
Left Visual Fields
- Gathers info from left side of environment
- Eventually interpreted in right side of brain
Right Visual Fields
- Gathers info from right side of environment
- Eventually interpreted in left side of brain
Medial Rectus
- Turns eye medially
- Oculomotor Nerve (III)
Inferior Rectus
- Depresses eye
- Moves eye medially
- Oculomotor Nerve (III)
Superior Rectus
(2 + nerve)
- Elevates eye
- Moves eye medially
- Oculomotor Nerve (III)
Inferior Oblique
(3 + nerve)
- Elevates eye
- Moves eye laterally
- External rotation
- Oculomotor Nerve (III)
Superior Oblique
(3 + nerve)
- Internal rotation
- Depresses eye
- Moves laterally
- Trochlear Nerve (IV)
Lateral Rectus
- Turns eye laterally
- Abducens Nerve (VI)
Cataracts
- Lenses slowly become hardened and cloudy over time
- Vision looks blurry
- Light is unable to freely enter lens to be refracted onto retina
Diplopia
Double vision
What is the Auditory System / Ear
- The ear is a sensory organ for hearing
>External Ear
>Middle Ear
>Inner Ear
Auricle
- Shaped to funnel sound waves into the external acoustic canal so that sounds can be detected
- Can be seen externally
- Composed of elastic cartilage, covered with skin
- Helix (rim)
- Lobule (lacks cartilage)
The External Acoustic Canal (meatus)
- Tunnel between auricle and tympanic membrane
- Composed of elastic cartilage near auricle and becomes a cylinder through the temporal bone
- Lined with skin that has hairs & glands that secrete cerumen
Cerumen
Earwax; traps foreign material
Tympanic Membrane (4)
- Eardrum
- Canal terminates here
- Thin membrane of connective tissue
- Vibrates with sound, transmit sound energy to middle ear
Tympanic Cavity
- Air filled chamber
- 3 tiny bones
>malleus (hammer)
>incus (anvil)
>stapes (stirrup) - Malleus receives vibrations from tympanic membrane and conveys them towards inner ear
Bony Labyrinth
- Fluid filled
- 3 sections:
>vestibule
>semicircular canals
>cochlea
Vestibular System (3)
- 3 fluid filled semicircular canals
- Each canal contains equilibrium receptors
- Impulses sent along the vestibular portion of CN VIII
Cochlea (3)
- Spiral, bony chamber
- Contains the membranous endolymph-filled cochlear duct
- Houses Organ of Corti and terminates at cochlear nerve
Organ of Corti
- Sense organ of auditory system
- Contains tectorial membrane and tiny hairs (stereocilia)
- As fluid receives vibrations, membrane bends stereocilia and initiates action potential carried through cochlear nerve
Facial Nerve
- Located in inner ear
- Innervates stapedius; attaches to stapes
- Controls amnt of tension on bone, allowing for increased or decreased vibrations
- Controls intensity of sounds
Conduction Deafness
- Damage to outer or middle ear structures
- Cerumen build up
- Ossicle bone fusion
- Almost always partial
Nerve Deafness
- Damage to nerve pathway; receptor cells, cochlear nerve, or brain
- Can be partial or complete
Olfaction
One of the chemical senses (smell)
Olfactory Receptors
Activated by airborne chemical substances dissolved in fluid from mucous membrane
Olfactory Nerves (CN I)
(3)
- Bipolar receptor cells
- Found in the olfactory epithelium
- Travel through ethmoid bone at the cribriform plate
Olfactory Bulbs (3)
- Dendrites terminate here
- Masses of gray matter
- Synapse w/ other neurons in the pathway
Olfactory Tracts
Carry info to temporal lobes
Smell
- Combination of a limited number of primary odors detectable by the brain
>floral
>ethereal
>camphorates
>musky
>peppermint
>pungent
>putrid
Anosmia
- Loss of smell
- Due to:
>TBI
>Temporary or permanent
>Gradual or sudden
Gustatory System
Responsible for the special sense of taste
Taste (3)
- Gustation (anatomical word for taste)
- Chemical sense
- Activated by chemical substances dissolved in saliva
Tongue (4)
- Grips food
- Repositions food in the teeth
- Forms bolus of compact food
- Assists in swallowing
Tongue Anatomy
- Apex
- Root
- Frenulum
- Papillae
Tongue Papillae
Raised bumps on the tongue
3 Types of Tongue Papillae
- Circumvallate
- Fungiform
>both contain taste buds - Filiform
Taste Buds (2)
- Contain chemical receptors stimulated by chemicals in food
- Found on tongue, surface of mouth, and wall of pharynx
Gustatory Cells (2)
- Chemoreceptor cells of taste buds
- Terminates in a gustatory hair which projects into saliva
Supporting Cells (3)
- Forms bulk of taste bud
- Separate taste receptor cells from each other
- Help maintain gustatory cells
Basal Cells
- Stem cells
- Divide and differentiate into new support cells, then to new gustatory cells
Nociceptors
Pain receptors
Thermoreceptors
Temperature receptors
Taste Pathway
- Food chemicals contact gustatory hairs
- Generate action potential in dendrites wrapped around gustatory cells
- Facial nerve:
>taste on anterior 2/3 of tongue - Glossopharyngeal nerve:
>taste on posterior 1/3 of tongue - Thalamus
- Parietal lobe
Ageusia
- Loss of taste
>TBI
>Brain tumor - Also impacted by loss of smell
>Nasal congestion
The interior of the eye (posterior to the lens) is filled with ___.
Vitreous fluid
Vitreous Fluid
A gel-like fluid that fills the eye and helps to hold the retina firmly to choroid
True or False: the vision pathway begins at the optic tracts, crosses at the optic chiasm, and then moves through the optic nerve
False; the pathway begins at the optic nerves, crosses at the optic chiasm, and then moves through the optic tracts
Where is the LGN located?
Thalamus
Lateral Geniculate Nucleus
The region where the optic tracts terminate in the thalamus
True or False: the nasal visual field is the visual field on the lateral sides of each eye
False; the peripheral visual fields is the visual field on the lateral sides of each eye
What allows for 3D vision?
Overlapping information in the nasal visual fields allows for 3D 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
Medial side
Lateral side
(bilateral right visual fields)
The medial rectus turns the eye _____. The medial rectus is controlled by CN _____.
The medial rectus turns the eye medially. The medial rectus is controlled by CN III, oculomotor
What bone touches the inner ear to transmit vibrations?
Stapes
The semicircular canals contribute in this way to the body’s _____ sense.
Vestibular
The movement of the stereocilia stimulates the neurons to send impulses through the _____ nerve to the _______ lobe of the brain.
Cochlear
Temporal
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.
Olfactory nerves contain what type of receptor cells?
Bipolar receptor cells
The olfactory nerves travel through what bone?
Ethmoid bone at the cribriform plate
What is the order of the olfactory nerve pathway?
Olfactory nerves → olfactory bulbs → olfactory tracts→ temporal lobes
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
True or False: The taste pathway sends signals via only one cranial nerve to the brain
False; two nerves - facial and glossopharyngeal
