Nervous System VII Flashcards
What are the components and openings of the orbit?
Superior orbital fissure
-CN III, IV, V1, VI, superior ophthalmic
Inferior orbital fissure
-V2, zygomatic nerve, inferior ophthalmic v., infraorbital a. and v.
Optic canal
-CN II, ophthalmic a.
Nasolacrimal canal
-Nasolacrimal duct from lacrimal fossa to nasal cavity (inferior meatus)
What are the accessory structures of the eye?
Eyelids(palpebrae)
-Tarsal plate
-conjunctiva
Lacrimal apparatus
Describe the eyelids(palpebrae)
Tarsal plate
- Connective tissue plate
- supports eyelids
- tarsal (meibomian )glands
- modified sebaceous glands
- prevent eyelid adhesion
Conjunctiva
- mucous membrane
- non keratinized stratified squamous with goblet cells
- pelpebral conjunctiva
- lines inner aspect of eyelids
- bulbar conjunctiva
- passes from eyelids onto anterior surface of the eyeball
Describe the lacrimal apparatus
Lacrimal glands-
Produce and drains lacrimal fluid (tears)
-watery secretion
-protect, cleans, lubricates, & moistens the eyeball
-contains lysozyme
-protective bactericidal enzyme
Parasympathetic stimulation
What 8s the flow of tears?
- Lacrimal gland
- Lacrimal ducts
- Superior or inferior lacrimal canal
- Lacrimal sac
- Nasolacrimal duct
- Nasal cavity
What is the wall of the eyeball?
Three layers
Fibrous tunic
- outer layer
- avascular
- cornea
- sclera
Vascular tunic (uvea) Middle layer -choroid - ciliary body - iris
Retina
- inner layer
- pigmented layer
- neural layer
- photosensitive
What is the structure and function of the cornea?
3 layers
Outer: non keratinized stratified squamous epithelium
Middle layer: collagen fibers and fibroblasts
Inner: simple squamous epithelium
Function: focus light onto retina
What is the structure and function of the sclera?
Dense connective tissue- collagen and fibroblasts
Function : gives shape to the eyeball imparts its rigidity attachment site of the extrinsic eye muscles
What is the function of the iris?
Suspend between the cornea and lens
Radial muscles(dilator pupillae) - make the pupil larger
Circular muscles (constrictor muscles)- make the pupil smaller
Function: regulate the amount of light entering through the pupil
What is the function of the ciliary body?
Ciliary process- vascularized fold of the CB, secretes aqueous humor
Zonular fibers- suspensiry ligaments of the lens, extending from the ciliary process to the lens
Ciliary muscles- pulls on the zonular fibers - changes lens shape
What is the function of the choroid?
Provides nutrients to posterior retina
Melanin absorbs stray light
Summarize vascular tunic contents
The vascular tunic (uvea) contains blood vessels and melanocytes
Contains:
- Iris
- Ciliary body
- Choroid
Describe pupil
Autonomic reflexes regulate pupil diameter
Bright light
- parasympathetic neurons stimulate circular muscles (sphincter pupillae)
- decrease in size (constriction )
Dim light
- sympathetic neurons stimulate radial muscles (dilator pupillae)
- increase in size (dilation)
Describe the vitreous chamber
Vitreous body
- jelly-like substance
- contributes to intraocular pressure
- helps maintain shape of eye
- water, collagen fibers, hyaluronic acid
Describe the anterior cavity
-anterior chamber
+between cornea & iris
- Posterior chamber
- Behind iris and in front of zonular fibers & lens
- Filled with aqueous humor
- watery fluid
- nourishes lens and cornea
- main source or intra ocular pressure
