Special Senses, Ch 15 Flashcards
Two thin folds that cover the anterior part of the orbit. Prevents foreign objects from entering the eye and distributes tears across the surface during blinking.
Eyelids
Palpaebrae
Each eyelid is stiffened by this piece of dense regular collagenous ct. Modified sebaceous glands are located within these, secreting oil to prevent the eyelids from sticking together.
Tarsal plate
Tarsal glands
The upper and lower eyelids meet at the edges of the orbit at what areas?
This fleshy structure is found in one area, contains sebaceous glands that secrete a whitish lubricating substance.
Medial and lateral commissures, also
Medial and lateral canthi
Lacrimal caruncle
A thin epithelial membrane that lines the posterior surface of the eyelids as this. Then turns back on itself as this to cover the anterior surface of the white part of the eye. Translucent, which permits the observation of blood vessels beneath it.
Conjunctiva
Posterior is palpebral, anterior is bulbar
Conjunctivitis, pink eye, viral or bacterial
Produces tears and drains them from the eye. Part of it is this gland, in the superolateral region of the orbit, just posterior to the conjunctiva. When stimulated by ANS, ducts release tears and mucus into the conjunctival sac to lubricate and wash away dust and debris.
Lacrimal apparatus
Lacrimal gland
Tears that have been swept across the eye first enter these tiny holes in the medial edge of each eyelid. They are continuous with these small ducts that empty into this sac. The sac is located in a small depression in the lacrimal bone and drains into a duct.
Lacrimal puncta
Lacrimal canaliculi
Lacrimal sac
The lacrimal sac drains into this duct, which travels through the lacrimal and maxillary bones to reach the inferior nasal meatus, just inferior to the inferior concha.
Nasolacrimal duct
Six skeletal muscles that have their origins on the walls of the orbit and insert into the outer layers of each eyeball. Produce very small, precise movements, so they are along the most highly innervated skeletal muscles in the body. Innervated by oculomotor (III), trochlear (IV), abducens (VI).
Superior, inferior, lateral, medial rectus
Superior oblique
Inferior oblique
Extrinsic muscles of the eye that extend from a common tendinous ring on the posterior wall of the orbit to their respective insertions on the eyeball.
Superior, inferior, lateral, medial rectus muscles
Extrinsic eye muscle that travels from the posterior orbit along the medial wall and through a fibrous loop before inserting on the superolateral part of the eyeball.
Superior oblique muscle
Trochlea
Extrinsic eye muscle that sweeps from the medial floor of the orbit to insert on the inferolateral part of the eyeball.
Inferior oblique muscle
What are the accessory structures of the eye?
Eyelids Eyebrows Eyelashes Conjunctiva Lacrimal apparatus Extrinsic eye muscles
If the eyes cannot move together, they send slightly different images to the brain, which is interpreted as blurred or double vision, called this. If present as birth, it’s known as what?
Diplopia
Strabismus, lazy eye
The outermost layer of the eyeball
The middle layer
The innermost layer
Fibrous layer
Vascular layer
Neural layer/retina
The white part of the eye, part of the fibrous tunic. 5/6ths of th eyeball. Numerous collagen fibers allow it to resist deformation from internal and external forces, maintaining its shape. The fibers arrange irregularly, making it opaque.
Sclera
Part of the fibrous tunic, but is translucent, allowing it to admitting and focusing light. This is because of the orderly parallel arrangement of collagen fibers, relative lack of water in the tissue, and absence of blood vessels. Avascular, getting O from fluid behind it as well as air. Many pain receptors, few touch.
Cornea
The most extensive component of the vascular layer, containing many capillaries as well as a pigment to reduce the scattering of light.
Choroid
Part of the vascular tunic, the choroid is continuous with this, which contains a ring of smooth muscle that surrounds the lens. Fine threads connect it to the lens. Contraction and relaxation of the smooth muscle changes the shape of the lens to focus light on the retina.
Ciliary body
Suspensory ligaments
The colored portion of the vascular layer just anterior to the ciliary body. Color is determined by the amount of melanin. Surrounds this circle, which is the opening through which light enters the eye.
Iris
Pupil
The iris contains these two muscles that protect the eye and improve vision by controlling how light enters. The first contracts following parasympathetic stimulation and constricts the pupil. The other contracts following sympathetic, with fibers in a radiating pattern that causes it to enlarge the pupil.
Pupillary sphincter
Pupillary dilator
In the retina, what are the two layers? What is the boundary between the anterior retina and the posterior edge of the ciliary body known as? Serrated line.
Superficial layer that is a thin, pigmented epithelium that reduces scattering of light and nourishes the photoreceptors.
Deep layer that contains photoreceptors and the cells that give rise to the optic nerve.
Ora serrata
An area in the retina that contains high density of photoreceptors relative to the rest of the retina. It allows for extremely detailed vision, enabling focus on a particular object. Located in the center of a yellowish region which also has a lot of the receptors.
Fovea centralis
Macula lutea
Area of the retina where the axons of the optic nerve gather, without any photoreceptors. Therefore it doesn’t capture an image and is a blind spot.
Optic disc
How are the retina’s epithelium and photoreceptors nourished?
How are the deeper structures supplied?
Blood vessels in the choroid.
Branches of the retinal artery, which enters the eye through the optic nerve.
The blood vessels are visible through the pupil.
A slightly flattened sphere located posterior to the iris and pupil that focuses light on the retina from objects near the eye. Surrounded by the ciliary body and connected to it by suspensory ligaments. Contains cells known as ____ fibers that lack nuclei and are tightly packed to make them transparent.
Lens
Maintains shape through elastic fibers found in its capsule.
The large posterior cavity of the eyeball is filled with this gelatinous material, which presses the retina against the choroid and helps maintain shape. Mostly water and collagen, very few cells. Hyaloid canal passes through from the lens to the optic nerve.
Vitreous humor
The anterior cavity of the eyeball consists of two smaller cavities, one between the lens and iris, and one between the iris and cornea. These are filled with this, secreted by the ciliary body. Flows from the back through the pupil to the front, and then into a blood vessel that circles the anterior edge of the iris.
Posterior chamber
Anterior chamber
Aqueous humor
Scleral venous sinus
The greatest degree of refraction, about two thirds of the eye’s refractive power, occurs how? It has a refractive index like what?
Occurs as light passes through the cornea
Like water
Additional refraction occurs how? It has a refraction index like that? What does this part of the provide for?
As light passes through the lens
Like the aqueous humor
Fine refractive adjustments
When the eye is relaxed and focusing on a distant object, what state of the eye is this? The cornea provides most of the needed refraction, and the lens in its normal flattened shape provides the rest.
Emmetropic state of the eye
The ability of the lens to change its shape from flattened to round. In this state its curved surface refracts light to a greater extent and can focus it on the retina, because diverging rays from nearby objects require a greater degree of contraction beyond what the cornea can provide.
Accommodation
When viewing distant objects, what movement increases tension in the suspensory ligaments, flattens the lens, and reduces refraction?
The smooth muscle of the ciliary body relaxes, moving the ciliary body away from the lends.
When accommodation occurs in the viewing of nearby objects, what movement decreases tension on the suspensory ligaments, reducing their pull on the lens? This change in shape increases refraction and focuses light from nearby objects on the retina.
The ciliary muscle contracts and the ciliary body moves closer to the lens. The ligaments reduce their pull on the lens.
Two processes that must occur in order to focus on nearby objects, in addition to accommodation? In the first, pupils construct slightly to cover the edge of the lens, refracting further. Second, the eyeballs move medially.
Pupillary construction
Convergence
The closest point at which we can focus on an object is called?
The near point of accommodation.
As we age the lens gradually stiffens and cannot accommodate as well.
Difficulty with close activities.
Curvature of lens or cornea is irregular and rays are not evenly refracted
Presbyopia
Astigmatism
The length of the eyeball is normal in the anterior-posterior direction and the lens can focus light on the retina.
Emmetropia
The eyeball is too short or the cornea is too flat. The lens cannot round up enough, and the image focuses behind the retina, causing blurriness when viewing things up close. How is refraction increased?
Hyperopia
Refraction is increased by using a lens with convex surfaces
The distance between the cornea and the retina is too long, or the cornea curves too much. The lens cannot flatten enough, which focuses the light in front of the retina, and blurs the image when viewing distant objects. How is the refraction corrected?
Myopia
Corrected with a concave lens that diverges light before it strikes the lens of the eye.
Contains pigments that allow us to perceive color, and funciton best in bright light. 5 million cones, highly concentrated in the fovea centralis. None at the retina. Focusing on an object.
Cones
Cannot detect color, but they are very sensitive and capable of responding in less intense light. Ability to see at night. 100 million, none occur in the fovea centralis. Increases as you move away from the retina. Peripheral vision.
Rods
Cones and rods consist of cell bodies connected to these. One houses stacks of flattened discs that absorb light and are formed from segments of the plasma membrane. The other contains mitochondria and organelles, generate new discs for first ones.
Outer segments
Inner segments
What happens to retinals of rods in the dark?
It is bent into a configuration known as cis-retinal.
Each disc in a rod contains this pigment in its membrane, and do by distinguish between different wavelengths/colors of light. It’s composed of this protein and this pigment.
Rhodopsin
Protein opsin
Pigment retinol
Each disc in a cone, containing this pigment made of what components? It is similar to opsin but absorbs different wavelengths of light.
Iodopsin
Retinal
Protein photopsin
What does the outer ear consist of?
The middle?
The inner?
Outer: auricle and external auditory canal
Middle: hollow, air-filled chamber in the temporal bone lined with mucous membrane
Inner: cavity in the temporal bone divided into three regions
Elastic cartilage covered with skin, except for the fleshy lobule? It funnels sound waves into this, a slightly curved tunnel through the temporal bone that ends at what?
Auricle/pinna
External auditory canal/external acoustic meatus
Tympanic membrane/eardrum
What are the modified sweat glands that excrete ear wax, aka what?
Ceruminous glands
Cerumen
The middle ear is connected to the nasopharynx by what, which serves to equalize air pressure on both sides of the tempanic membrane?
Pharyngitympanic tube
How is pressure related to the pharyngotympanic tube and the tympanic membrane?
Air pressure in the external auditory canal changes relative to that in the middle ear. Pressure difference causes eardrum to stretch and bulge inward or outward. Excess tension reduces the ability of it to vibrate.
The middle ear contains these three small bones, which are connected by synovial joints and together form a bridge extending across the middle ear.
Auditory ossicles
Malleus, hammer
Incus, anvil
Stapes, stirrup
The boundary between the air-filled middle ear and fluid-filled inner ear, attached to the stapes in the medial wall, which is attached to the eardrum and the malleus.
Oval window
Small skeletal muscles that attach to the ossicles. One inserts on the malleus to pull the eardrum medially and tense it. The other inserts on the stapes to reduce movement of the ossicles as a unit.
Tensor tympani
Stapedius
Within the membranous labyrinth of the inner ear, there’s fluid with a higher concentration of K than Na, ICF-like. Between the walls of the bony and membranous is a fluid with more K than Na, ECF-like.
Endolymph
Perilymph
Located medial to the inner ear, its wall containing the membranous oval window. Houses these two portions of the labyrinth filled with endolymph, which contain receptor cells that convey stimuli about head tilting and movement.
Vestibule
Utricle
Saccule
The receptors transmit the stimuli to neurons that form the vestibular portion of the Vestibulocochlear nerve.
The utricle is continuous with three tubes of membranous labyrinth called what, which are enclosed by what? Detect rotational movement of the head in any plane.
Semicircular ducts
Semicircular canals
At the base of each semicircular duct is this swollen bulb that contains receptor cells innervated by the vestibular portion of the vestibulocochlear nerve. Within each are this cluster of hair cells and supporting cells.
Ampulla
Crista ampullaris
Gelatinous mass called cupula
This bony part features a membrane-covered opening called what, that separates the middle and inner ear?
Cochlea
Round window
Within the cochlea we find this spiral-shaped portion of the membranous labyrinth known as what, which is connected to the saccule and filled with endolymph.
Cochlear duct, scala media
Two chambers that spiral through the cochlea, filled with perilymph.
Superior scala vestibuli
Inferior scala tympani
Epithelium that forms the boundary between the cochlear duct and the scala vestibuli, separating the endolymph and perilymph. Serves as a diffusion barrier to maintain concentrations of ions.
Vestibular membrane
Collagenous connective tissue that is connected to a shelf of bone, separating the cochlear duct and the scala tympani. Narrow and stiff near base of the cochlea, but widens and becomes more flexible near tip.
Basilar membrane
Supported by the basilar membrane, this organ contains receptor cells for hearing. Located within the cochlear duct and is where energy from sound waves is transited into neural impulses.
Spiral organ
Organ of Corti
Pressure waves from what sounds travel a short distance causing the basilar membrane to vibrate where it is narrow and stiff?
Travel farther into the cochlea and cause the membrane to vibrate where it is wide and flexible?
High frequency
Low frequency
For very low frequency vibrations we cannot hear, the travel to the tip of the cochlea, where the scala vestibuli connects with the scala tympani at this opening?
Helicotrema
They they travel back to the vestibule via the tympani where they cause movement of the round window.
The spinal organ of the ear contains these receptor cells. They are grouped into a single row of? And three rows of?
Hair cells
Inner hair cellls, detect sound
Outer hair cells
Each hair cell of the ear has this microvilli which project from the cell into the endolymph of the cochlear duct?
Stereocilia
Vary in length and are arranged from tallest to shortest
How is sound transmitted to the inner ear?
The basilar membrane moves up toward the tectorial, bending the steriocilia toward the tallest one. This opens K ion channels that depolarize the hair cell. This releases neurotransmitters, triggering potentials in the cochlear nerve.
For very low frequency vibrations we cannot hear, the travel to the tip of the cochlea, where the scala vestibuli connects with the scala tympani at this opening?
Helicotrema
They they travel back to the vestibule via the tympani where they cause movement of the round window.
A stiff membrane that extends over the stereocilia hair cells and sandwiches them between the basilar membrane and this one. The cilia on the outer had cells contact it, the inner do not.
Tectorial membrane
The sense of equilibrium depends on input from three sources?
The visual system
The proprioceptors in muscles and joints
The vestibular system
Both the utricle and saccule have structures known as what, located in the epithelium lining its wall? Contains the receptor cells for head position and movement.
Macula
Receptor cells in the macula contain steriocilia and one true cilium, which is taller than the stereocilia?
These are embedded in a gelatinous mass which is suspended in the endolymph of the chambers, which has crystals.
Kinocilium
Otolithic membrane
Otoliths are crystals of calcium carbonate that increase the membranes density
In the utricle, the stereocilia do what when the head is upright and stationary? And what when the head tilts or bends?
In the saccule they do what?
Point vertically, bend
Horizontally, bend
They release glutamate for equilibrium when bent
