Special Senses Flashcards
(48 cards)
Define Emmetropic
A normal eye with no change occurring in the lens with distance vision
Define Myopic and how is it corrected?
Someone who is nearsighted or short-sighted, as the image falls in front of the retina as the eyeball is too long for the lens power. Corrected with concave lens.
Define Hyperopic and how is it corrected?
Someone who’s is far-sighted, as the image falls behind the retina. A convex lens is used to converge the light rays onto the retina.
What is Presbyopia?
The old age eye. People over 50, the lens no longer accommodates.
Define Canthi and what are they also known as?
The medial and lateral angles of the eye, where the two eyelids join in the corner of the eye.
Also known as medial and lateral commissure.
Define tarsal plates and their role
They are connective tissue that support eyelids internally and help to maintain firmness of the eyelids
What do tarsal glands do?
Produce oil secretion in the eyelid so the aqueous layer doesn’t dry out and the eyelid remains lubricated
What does the levator palpebrae supeioris do?
Elevates the eyelid
Name 3 associated lubricating glands?
- Tarsal glands
- Sebaceous glands
- Ciliary glands
What moves the eyebrows medically to form a frown?
Corrugator Supercilii
What does lacrimal fluid (tears) contain?
1.Mucous
2.Antibodies
3.Lysozyme
Describe the pathway lacrimal fluid follows
- Enter the superior lateral eye via excretory ducts
- Exit medically and drain into lateral punctum
- Drain into nasolacrimal duct
What condition is caused by the inflammation of the conjunctiva?
Conjunctivitis (pinkeye)
What is the annular ring and which rectus muscle originate from it?
It is the common tendinous attachment and the lateral, medial, superior and inferior rectus originate from it.
Define strabismus
Congenital weakness of the extrinsic eye muscles
What is the interval cavity of the eyeball filled with?
Fluids called humors
What is the role of the lens?
Separates the internal cavity into an anterior and posterior segment.
What is the anterior and posterior segment filled with?
Anterior - aqueous humor
Posterior - vitreous humor
What is the fibrous layer and what are its components?
It is the outermost layer of the eye and is composed of dense avascular tissue
Composed of sclera and cornea
What is the vascular layer and what is it composed of?
It is the middle layer called the uvea and is composed of:
- Choroid
- Ciliary body
- Iris
What is the choroid and what is it’s function?
It is a dark brown pigmented membrane that forms the posterior portion of the uvea and supplies blood to the eye tunics
What is the sphincter pupillae and what is it’s role?
It is a circular muscle surrounding the eye and when it contracts, it constricts the pupil, making it small
What is the dilator pupillae and what is it’s role?
It is a muscle and when it’s fibers radiate outwards, causes pupil to dilate
Describe how the eyes have a blind spot?
- Axons of ganglion cells converge, and exiting the eyeball via the optic disc, forming the optic nerve
- The optic disc is where the optic nerve leaves the eye so it is not covered by the sclera and lacks photoreceptors, thus the light focused on the optic disc cannot be seen