Chapter 6: Special Senses Flashcards
What are the accessory structures of the eye?
- Eyelids
- Eye lashes
- Lacrimal apparatus
- Extrinsic eye movement
___________ - is a thin protective mucous membrane with numerous goblet cells.
Conjunctiva
Functions of Eyelids (upper/lower lids).True or False:
- Shade the eyes during sleep.
- Protect the eye from excessive light and foreign objects.
- Spread lubricating secretions over eyeball.
True
__________ - project from the border of each eyelid.
Eyelashes
__________ - Help protect the eyeballs from foreign objects, sweat and the direct rays of the sun.
Eyebrows
What Produce and drains tears?
Lacrimal Apparatus
Tears then pass medially over the anterior surface of the eyeball, to enter two small openings called ___________ .
lacrimal puncta
How many ducts does Lacrimal glands have?
6-12 excretory lacrimal ducts
Size of lacrimal glands is compared to a size of :
size of an almond
Flow of tears: True or False:
Lacrimal glands – Excretory lacrimal ducts – superior/inferior lacrimal canal – lacrimal sac – nasolacrimal duct – nasal cavity.
True
It is known as lacrimal fluid .
Tears
What is the function of Tears?
protects, cleans, lubricates and moistens the eyeball.
Water solution, which contains salts, some mucus and lysozymes.
Lacrimal fluid ( Tears )
What composes the Extrinsic eye muscles?
Six in total Innervation from CN III, IV and VI
- Superior rectus
- Inferior rectus
- Lateral rectus
- Medial rectus
- Superior oblique
- Inferior oblique
______________ - Contains the eyeball, optic nerve, ocular muscle, fascia, nerves, vessels, fat, lacrimal gland and sac.
The Orbit of the eye
What are the Three Layers of eyeball?
- Outer fibrous layer
- The middle vascular layer (pigmented)
- The inner layer
Layer of eyeball that is composed of the retina, consisting of optic and non-visual parts.
The inner layer
Layer of eyeball that is composed of the sclera and cornea.
Outer fibrous layer
Layer of eyeball that is composed of the choroid, ciliary body and iris.
The middle vascular layer (pigmented)
_________ - is the opaque part of the fibrous coat of the eyeball.
Sclera
Sclera covers the ____________ of the eyeball.
posterior 5/6
The anterior part of sclera is known as:
” white of the eye “
____________ is the transparent part of the fibrous coat, covering the anterior 1/6 of the eyeball.
cornea
A mucous membrane lines the eyelids and covers the sclera in front.
conjunctiva
The conjunctiva is kept moist by tears, formed in the ________ .
lacrimal gland
__________ - Posterior portion of the vascular tunic. It is the brown membrane between the sclera and retina which prevents the scattering of incoming light rays.
choroid
___________ - is the anterior portion of the vascular tunic and is very muscular. It connects the choroid with the circumference of the Iris.
ciliary body
_________ - is the coloured portion of the eyeball and lies around the anterior surface of the lens which lies directly behind the pupil.
Iris
_________ - is for transmitting light, may vary in size, and regulating amount of light entering the eye.
Pupil
When we look at distant objects, the ciliary muscle is ______ and the lens has a slightly __________ . To focus on near objects the ciliary muscle ________ . it causes the lens to _________ even more.
relaxed
curved shape
contracts
bulge and curve
True statement regarding Cataract. Except:
- Over-exposed to UV radiation from sunlight, the lens may become hard and lose its transparency and become milky in appearance (cataract).
- Cataracts will not lead to blindness if untreated.
- The cataract can be removed surgically and replaced with an implant.
2
Contains microscopic photoreceptor cells called ___________ (due to their shape).
rods and cones
Photoreceptor cells that do not provide colored vision.
Rods
Photoreceptor cells that provide colored vision.
cones
What will happen if there is a Loss of cone system?
Loss of cone system produces legal blindness.
It is the stimulus that results in vision.
Light
Light enters the eye through the ______ and is refracted or bent, so that it is focused on the _______ .
pupil
retina
Light as stimulus – pupil – retina – rods and cones synapse – Nervous signals — optic nerve – brain — visual cortex of the occipital lobe (visual interpretation) which results in seeing.
Visual pathway
The Structure of eyeball are:
Fibrous tunic
Vascular tunic
Retina
Lens
Fibrous tunic is composed of :
i. Cornea
ii. Sclera
Vascular tunic is composed of :
i. Iris
ii. Ciliary body
iii. Choroid
________ - Provides vision blood supply and absorbs scattered light.
Choroid
_______ - regulates amount of light that enters eyeball.
Iris
__________ - alters the shape of the lens for near and far vision.
Ciliary body
It receives light and converts it into receptor potentials and nerve impulses.
Retina
The function is to Refracts light.
Lens
_________ - has functions for hearing, equilibrium and balance.
ear
What are the three parts of the ear?
- External ear
- Middle ear
- Inner ear
There are two parts to the external ear :
- auricle
- external auditory canal
It is a curving tube about 1 inch in length. It extends into the temporal bone and ends at the eardrum.
external auditory canal
The rim of the auricle is called the _______ and the inferior portion is the ______. .
helix
lobule
It is a thin semitransparent partition between the external auditory canal and middle ear.
eardrum
The skin of the canal contains short hairs and ______________ (produce cerumen or earwax).
ceruminous glands
True or False:
The cerumen may block the canal and impair hearing. Sound waves travelling through the canal, strike the eardrum and cause it to vibrate.
True
____________ is a cavity hollowed out of the temporal bone, lined with thin epithelium.
middle ear
The middle ear houses three tiny bones these are:
malleus, incus and stapes.
The window that separates the middle ear from the inner ear.
oval window
The handle of the malleus attached to the inside of the _______ . The head of the malleus attached to the _______ . The incus attached to the ______ .
eardrum
incus
stapes
True or False:
When sound waves are transmitted and amplified by ear bones, it passes through the middle ear. The movement of the stapes against the window, causes movement of fluid in the inner ear.
True
______________ connects the middle ear with the nasopharynx. If this tube becomes blocked, it can lead to a middle ear infection.
Auditory (eustachian) tube
Activation of mechanoreceptors in the ________ , generates nervous impulses that result in hearing and equilibrium.
inner ear
The inner ear consists of three spaces in the temporal bone, assembled in a complex maze called the __________ .
bony labyrinth
This labyrinth is filled with a watery fluid called _________ .
perilymph
The bony labyrinth is divided into the ________ , semicircular canals and the _________.
vestibule
cochlea
There is a membranous labyrinth that follows the shape of the bony labyrinth and is filled with a thicker fluid called __________ .
endolymph
Specialized mechanoreceptors for balance and equilibrium are located in the three _____________ and the __________ .
semicircular canals
vestibule
Within each semicircular canal, there is a dilated area ( _______ ) which contains a specialized receptor called _____________.
ampulla
crista ampullary
Nerves from the vestibule join nerves from the semicircular canals, to form the ____________ .
vestibular nerve
Organ of hearing that lies in the cochlea:
organ of corti
___________ - Is a membranous tube within the bony cochlea.
cochlear duct
Specialized hair cells on the ____________ , generate nerve impulses, when movement of endolymph sets in motion, any sound waves bends them. The impulses are sent through the ___________ .
Organ of Corti
cochlear nerve
Nerve that are combine to form the acoustic nerve or CN VIII which eventually reaches the cerebellum and medulla and parts of the cerebral cortex.
The vestibular nerve and the cochlear nerve
