Vision Flashcards
The act of seeing
Vision
More than ________ the sensory receptors in the human body are loacated in the eyes.
half
List the accessory structures of the eye
eyebrows
eyelashes
eyelids
lacrimal apparatus
extrinsic eye muscles
It protects the eyes from foreign objects, from perspiration and direct rays from the sun.
Eyebrows and eyelashes
It shades the eye during sleep. Also, it protect the eyes from excessive light and foreign objects, and spread lubricating secretions over the eyeballs.
Upper and lower eyelids (Palpebrae)
The space between the upper and lower eyelids that exposes the eyeball.
Palpebral fissure
What are the angles in the palpebral fissure?
Lateral commissure
Medial commissure
This angle in the palpebral fissure is narrower and closer to the temporal bone.
Lateral commissure
This angle in the palpebral fissure is broader and nearer the nasal bone.
Medial commissure
In the medial commissure is a small, reddish elevation, which contains sebaceous (oil) gland and sudoriferous (sweat) glands.
Lacrimal caruncle
A thick fold of connective tissue that gives form and support to the eyelids.
Tarsal plate
Is a row of elongated modified sebaceous glands that secrete a fluid that helps the eyelid from adhering to each other.
Tarsal glands or Meibomian glands
It is a thin, protective mucous membrane composed of nonkeratinized stratified squamous epithelium with numerous goblet cells that is supported by areolar connective tissue.
Conjunctiva
Lines the inner aspect of the eyelids.
Palpebral conjunctiva
Passes from the eyelids onto the surface of the eyeball, where it covers the sclera but not the cornea.
Bulbar conjunctiva
Group of structures that produces and drains lacrimal fluid or tears in a process called lacrimation
Lacrimal Apparatus
It is about the shape and size of an almond, secretes lacrimal fluid which drains into 6-12 excretory lacrimal ducts.
Lacrimal Gland
These are 2 small openings in each of the papilla of the eyelid at the midline commissure of the eye.
Lacrimal Puncta/punctum
These are 2 small ducts connected with to each lacrimal punctum.
Lacrimal Canals/ canaliculi
(superior & inferior lacrimal canal)
It is the expanded portion of the nasolacrimal duct.
Lacrimal Sac
It is the expanded portion of the nasolacrimal duct.
Lacrimal Sac
It carries the lacrimal fluid into the nasal cavity.
Nasolacrimal Duct
Flow of Tears
- LACRIMAL GLAND secretes tears into
- LACRIMAL DUCTS, which distribute tears over the surface of eyeball
- SUPERIOR OR INFERIOR LACRIMAL CANALICULI drain tears into
- LACRIMAL SAC, which drains tears into
- NASOLACRIMAL DUCT, which drains tears into
- Nasal Cavity
Composition of the lacrimal fluid or tears
Salts
Mucus
Lysozyme
What are the functions of the lacrimal fluid
Protection
Cleans
Lubricates
Moistens
How much lacrimal fluid is produced per day in each lacrimal gland.
1mL
What do you call the bony depressions of the skull wherein the eyes sit?
Orbits
Help protect the eyes, stabilize them in three dimensional space, and anchor them to the muscles that produce their essential movements.
Orbits
Th extrinsic eye muscles extend from the walls of the bony orbit to the sclera of the eye and are surrounded by a significant quantity of __________________.
Periorbital fat
What are the six extrinsic eye muscles?
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique
Extends from the walls of the bony orbit to sclera of the eye.
Extrinsic eye muscles
What supplies the six extrinsic eye muscles?
oculomotor (III)
trochlear (IV)
or abducens (VI) nerves
Turns the eye upward
Superior rectus
Turns the eye downward
Inferior rectus
Towards the midline
Medial rectus
Towards the lateral side
Lateral rectus
These muscles preserve the rotational stability of the eyeball.
Oblique muscles
Rotates the eyeball so the cornea turns in a downward and outward direction.
Superior Oblique
Rotates the eyeball so the cornea turns in a upward, outward direction.
Inferior Oblique
The diameter of eyeball
2.5 cm (1 inch)
Of the total surface of the eyeball, how much is exposed?
1/6
Bony pyramidal shaped cavity of the skull that holds the eyeball.
Orbit
Enumerate the 3 layers/tunics of the eyeball,
Fibrous tunic
Vascular tunic/Retina
Nervous tunic
The superficial layer of the eyeball and consists of the anterior cornea and posterior sclera outer later and it is AVASCULAR.
Fibrous tunic
It is a transparent coat that covers the colored iris. It is located on the anterior portion and has no capillaries.
Cornea
What composes the outer surface of the cornea?
Nonkeratinized stratified squamous epithelium
What composes the middle coat of the cornea?
collagen fibers and fibroblasts
What composes the inner surface of the inner surface of the cornea?
simple squamous epithelium
Permits light to enter the eye (bend/refracts light)
Cornea
The “white” of the eye, is a layer of dense connective tissue made up of collagen fibers and fibroblasts.
Sclera
Covers the entire eyeball except the cornea.
Sclera
It gives shape to the eyeball, makes it more rigid, protects its inner parts and serves as a site of attachment for the extrinsic eye muscles.
Sclera
What cranial nerve pierces the posterior portion of sclera?
Optic (CN II)
An opening located at the junction of the sclera and cornea. Aqueous humor (a fluid) drains into this sinus.
Canal of Schlemm or Scleral Venous Sinus
The middle layer of the eyeball. It contains lots of blood vessels.
Vascular tunic/ Uvea
What are the three parts of the vascular tunic?
Choroid
Ciliary body
Iris
It is the posterior portion of the vascular tunic, lines most of the internal surface of the sclera.
Choroid
Its numerous blood vessels provide nutrients to the posterior surface of the retina.
Choroid