Sense Organ - The Eyes ( Finals ) Flashcards
develops as a neuroectodermal outgrowth of the embryonic prosencephalon that contacts surface ectoderm and is enveloped by induced mesodermal and neural crest mesenchyme.
eye (the organ for vision)
The definitive 1. ? and its 2. ? are contained within an orbit that is only partly bony.
- eye
- adnexa
Associated with the bulb of the eye what are the muscle that move eye
extraocular muscles
What surround and cushion the eye
periorbital fascia and fat
What protects the eye
eyelids and conjunctiva
What keeps the eye’s surface moist, provides the first barrier to infection, and helps to nourish the cornea
lacrimal apparatus
As a consequence of its dual origin, the eye has both what neural elements?
central and
peripheral neural elements.
What nerve is a central nervous system structure with myelin
formed by oligodendroglial cells
optic nerve
nerves of the 1. ? and 2. ? are peripheral nervous system structures with lemmocyte (Schwann cell) sheaths for myelin
- extraocular muscles
- iris
What are the two tunics that surrounds the optic nerve are homologous to the meninges surrounding the brain and spinal cord
vascular and fibrous tunics
What space of the optic nerve is continuous with the subarachnoid space of the brain and contains cerebrospinal fluid
intervaginal space
intervaginal space of the optic nerve is continuous with the subarachnoid space of the brain and contains what fluid?
cerebrospinal fluid
The eye includes the following:
• Orbit
• The eyeball or Globe
• Adnexa
•deep bony cavity in the rostral surface of the skull
•it houses the globe and adnexa
ORBIT
• Composed of very dense collagenous and elastic
tissue and fibrocytes
FIBROUS TUNIC
These are the functions of what part of Globe(Eyeball)?
Functions:
– gives the eyes its shape and stiffness by resisting pressure of internal fluid
– protects internal vascular and light sensitive portions of the eye from environment
– refracts (bends) the light and conducts light to retina
– provide site for attachment of extraocular muscles
FIBROUS TUNIC
– Opaque/white portion of the eye, approximately 75 % of the globes surface
– consists of a dense network of collagen and elastic fibers and their fibrocytes
sclera
– Transparent/clear portion of the eye, approximately 25% of anterior segment of fibrous tunic
– avascular, nutrients arrive thru the capillary loops at the limbus
– innervation: long ciliary nerves enters the cornea at the limbus
cornea
border where sclera and cornea meets
Limbus corneae
• Lies internal to fibrous tunic
• Extremely vascular and heavily pigmented
VASCULAR TUNIC
VASCULAR TUNIC referred to as?
“uvea”
VASCULAR TUNIC Three regions:
• Choroid
• Ciliary body
• iris
• Posterior part of vascular tunic, consists of dense meshwork of blood vessels
CHOROID
Which part of vascular tunic are these functions?
Functions:
– provide nutrient and oxygen to retina
– limits light scatter
– improves vision in low-light situations
Choriod
– structure adapted to increase light intensity under low-lighting situations
– avascular region of choroid
– contains rod shaped crystals that refract incoming light
Tapetum Lucidum
Tapetum Lucidum present in all domestic mammals except the?
pigs
• forms from thickening of choroid that is raised inward into posterior chamber of the eye
• suspends the lens within the eyes
• acts to change the thickness of the lens (accommodation)
CILIARY BODY
are smooth muscle bundles that originate on the sclera and attach to the base of the ciliary body
ciliary muscles
• Most anterior, smallest segment of vascular tunic
• Thin, flat circular structure attached to ciliary body
IRIS
– responsible for eye coloration
Melanin granules
– is the only pigment present in the iris
Melanin
central opening in the iris; round in dogs; has set of smooth muscles
Pupil
• radially arranged; draws pupil open and admits more light; sympathetic
pupillary dilator
• circumferentially arranged; draws the pupil closed; parasympathetic
pupillary constrictor (sphincter)
– inner most layer of the eye
Retina
Retina – inner most layer; having 3 parts and a divisionary zone, what are those 3?
– Optic - visual
– Ciliary – non-visual
– Iridial - non-visual