Ch. 15 - Special Senses Flashcards
Medial rectus
- Moves eye medially
- Oculomotor III
- muscle responsible for crossing ones eyes
Superior rectus
- elevates eye
- Oculomotor III
- muscle responsible for looking up
Inferior rectus
- Depresses eye
* Oculomotor III
Inferior oblique
- Elevates eye and turns it laterally
* Oculomotor III
Superior oblique
- Depresses Eye And turns it laterally
- Trochlea IV
- damage to Trochlear nerve causes inability to contract this muscle
Lateral rectus
- Moves eye laterally
- Abducens VI
- damage to cranial nerve VI causes inability to contract this muscle
- inability for eyeball to look right would indicate dysfunction of this muscle
Optic chiasm
- point where optic nerves are connected to each other just inside the cranial cavity and anterior to the pituitary gland
- area where medial ganglion cell axons cross over and project to opposite side of brain
- Half of the fibers of each optic nerve decussate here before reaching the visual cortex
Fovea centralis
• The portion of the retina with the greatest visual acuity
Vitreous humor
• A jelly like substance in the posterior cavity of the eye
Optic tract
- track that extends from the optic chiasma to the lateral geniculate nucleus of the thalamus
- The route of the ganglionic axons beyond the chiasma
Visual cortex
- Area in the occipital lobe of the cerebral cortex that integrates visual information and produces the sensation of vision
- The cerebral area that integrates messages from retina
Cataract
- increased cloudiness of the lens resulting in decreased vision or loss of vision
- treatment involves removal of the lens
Macula degeneration
- acute loss of vision; both eyes are typically involved
* Central vision is affected, while peripheral vision remains intact
Myopia
- difficulty seeing distant objects
- nearsighted
- eyeball is too long and the focal point is in front of the retina
Astigmatism
- cornea or lens is not uniformly curved, so images not sharply focused
- a type of refractory error
- The cornea or the lens is elliptically rather then spherically curved
Glaucoma
- increased intraocular pressure that can lead to loss of vision
- A state of elevated pressure with in the eye that occurs when the scleral venous sinus is obstructed so the aqueous humor is not reabsorbed as fast as it is secreted
- maybe caused by increased aqueous humor fluid production or failure to drain
- excessive pressure build up in aqueous humor; may destroy retina or optic nerve, resulting in blindness
Auditory ossicles
- tiny bones in the middle ear
* malleus, incus, stapes
Organ of corti
• structure in the cochlea in which hair cells transduce movements from soundwaves into electrochemical signals
Endolymph
• A fluid contained in the membranous labyrinth of the inner ear
Perilymph
• fluid between the membranous and bony labyrinth
Auditory tube
• connects the middle ear to the pharynx
Oval window
- A membrane covered opening that leads from the middle ear to the vestibule of the inner ear
- ossicles connect the structure to eardrum
Conjunctivitis
- inflammation of conjunctiva, usually from bacterial infection
- pink eye is an example of this
Why does a persons nose run when he cries?
• tears drain into the nasal cavity via the nasolacrimal duct
Intrinsic eye muscles
- ciliary muscles
- sphincter pupillae
- dilator pupillae
Color vision
• is a function of cone cells
Vestibulocochlear nerve - CN VIII
• responsible for hearing and balance
Olfactory nerve - CN I
• responsible for sense of smell
Optic nerve - CN II
• responsible for vision
Oculomotor nerve - CN III
• responsible for eye movements by controlling for the extraocular muscles
Trochlear nerve - CN IV
• responsible for eye movement
Trigeminal nerve - CN V
• responsible for cutaneous sensations of the face and controlling the muscles of mastication
Abducens nerve - CN VI
• responsible for eye movement
Facial nerve - CN VII
• responsible for the muscles involved in facial expressions, as well as part of the sense of taste and production of saliva
Glossopharyngeal nerve - CN IX
- responsible for controlling muscles in the oral cavity and upper throat
- part of the sense of taste and the production of saliva
Vagus nerve - CN X
• responsible for contributing to homeostatic control of the organs of the thoracic and upper abdominal cavities
Accessory nerve - CN XI
• responsible for controlling the muscles of the neck along with cervical spinal nerves
Hypoglossal nerve - CN XII
• responsible for controlling the muscles of the lower throat and tongue
Optic disc (blind spot)
• nerve fibers from all regions of the retina converge here and exit the eye by way of the optic nerve
Refraction
• bending of a light ray when it passes from one medium into another of different density
Emmetropia
- The condition in which the lens is flattened so that nearly parallel rays from a distant object are focused on the retina
- The normal resting condition of the lens
Accommodation
- The shape of the lens changes, depending on whether the eye is focusing on an object that is near or farther away
- The process of changing the shape of the lens is referred to as this
- The adjustment made when you view objects close to the eye
- accommodation for near vision requires contraction of the ciliary muscles
Presbyopia
- The increase in the near point of vision that develops with age
- it occurs because the lens becomes less flexible with increasing age, and it is the reason some older people say they could read with no problem if only they had longer arms
Convergence
• A medial rotation of the eyes that is accomplished by a reflex that stimulates the medial rectus muscle of each eye
Vestibule
• structure in the inner ear involved in balance
Movement of hair cells in semicircular canals signal
•the velocity of movement? Or the direction of motion?
➡️direction of motion
Hyperopia
- farsightedness
- ability to see distant but not close objects
- caused when cornea is too flat or lens has two little refractive power relative to length of eye
- eyeball is too short and the focal point is behind the retina
Ansomia
•loss of smell
Color blindness
- inherited trait
* A result of lack of one type of photopigment or cone type
Otosclerosis
• affects the auditory ossicles by an overgrowth of the bones causing deafness
Nervous tunic
Retina
Vascular tunic
- ciliary body
- choroid
- iris
Fibrous tunic
- cornea
* sclera
Cornea
• an avascular, transparent structure that permits light to enter the eye and bends that light as part of the eyes focusing system
External ear structures
- auricle (pinna)
- external auditory canal
- tympanic membrane
Inner ear structures
- bony labyrinth
- cochlea
- vestibule
- semicircular canals
Middle ear structures
- malleus
- incus
- stapes
- auditory tube
- chorda tympani
Filiform papillae
• have no taste buds but are the most numerous papillae on the surface of the tongue
Vallate papillae
- largest papillae but least numerous
* contain taste buds
Fungiform papillae
- mushroom shaped; scattered irregularly over the surface of the tongue
- look like small red dots
- have taste buds
Foliate papillae
- Leaf shaped
- in folds on the sides of the tongue
- contain most sensitive taste buds
- decrease in number with age
Anterior chamber of the eye
- lies between the cornea and Iris, and the smaller posterior chamber lies between the iris in the lens
- Chambers are filled with aqueous humor which helps maintain intraocular pressure
When does the lens of the eye thicken?
• when ciliary muscles contract
Visual sensations from images focused on the side of the retina are blurred because
• there are more rods than cones in this region
Arnold enters a darkened movie theater on a sunny summer afternoon. It takes many minutes for his eyes to adapt to the darkness because
• it takes some time for the retina to rebuild it’s rhodopsin stores from opsin and retinene
If a person’s right visual cortex is damaged, the injury will most likely affect vision from the
• nasal side of one eye and the temporal side of the other eye
Causes of smell and taste disorders
- A side effect of a drug
- infections that clog the nose
- A head injury
- allergies
A cochlear implant treats
Sensorineural deafness
The primary olfactory cortex is located
Temporal lobe
Adjustment to close range of vision involves
- extrinsic muscles of the eye activity
- change in the curvature of the lens
- constriction of the pupil
- ciliary muscle activity
Which auditory ossicles attached to the tympanic membrane?
•malleus
Farsightedness after the age of 45 is most likely caused by
Loss of lens capsule elasticity
Sclera venous sinus
- venous ring at the base of the cornea that drains the aqueous humor in the eye
- if obstructed can cause glaucoma
Structures of inner ear in order of transmission of action potential from spiral organ to temporal lobe:
1) hair cells
2) cochlea nerve fibers
3) cochlea nucleus
4) superior olivary nucleus
5) inferior colliculus
6) medial geniculate nucleus
7) auditory cortex
Eyebrows
• help shade eye from direct sunlight
Eyelids
• help keep eye lubricated by spreading tears over surface
conjunctiva
• thin transparent mucous membrane protecting inner surface of eyelid and anterior surface of sclera
Lacrimal apparatus
• production of tears
Extrinsic eye muscles
• movement of eyes
Structures of ear in order for transmission and interpretation of sound waves from external to inner ear:
1) auricle
2) external auditory canal
3) tympanic membrane
4) malleus
5) incus
6) stapes
7) oval window
8) Perilymph of scala vestibuli
9) vestibular membrane
10) Endolymph
11) basilar membrane
12) hair cells
The only major sense that does not pass through the thalamus on its way to the cerebral cortex
Olfaction
Structures within the external auditory canal that prevent foreign objects from reaching tympanic membrane
- hair
* cerumen
Structures in order as vibrations pass from external to inner ear
1) tympanic membrane
2) malleus
3) incus
4) stapes
5) oval window
Lens
• transparent, biconvex structure in the eye
_____ contain the photoreceptive molecule rhodopsin and ______ contain the photoreceptive molecule iodopsin.
Rods; cones
The white outer layer that protects the internal structures of the eye, maintains the shape of the eye, and provides an attachment point for the extrinsic muscles of the eye
• sclera
