EYE AND ORBIT Flashcards
a pyramid-shaped bony recess in the anterior part of the skull
orbit
the orbit is lined by a periosteum called the ______
periorbital fascia
seven bones contribute to the framework of each orbit: ______, ______, ______, ______, ______, ______, and ______ bone
maxilla, zygomatic, frontal, ethmoid, lacrimal, sphenoid, palatine
contents of the orbit:
- ______ (organ associated with vision)
- ______ muscles
- ______, their branches, and ganglions that are associated with the eye and orbit
- ______ apparatus
Eye, Extrinsic, Nerves, Lacrimal
Bony boundaries of optic canal
Lesser Wing of Sphenoid
Structures Passing Through the optic canal
Optic Nerve
Ophthalmic Artery (a branch from the
internal carotid artery)
Bony boundaries of superior orbital fissure
Lesser Wing of Sphenoid
Greater Wing of Sphenoid
Structures Passing Through the superior orbital fissure
Ophthalmic Division of Trigeminal Nerve
(lacrimal, frontal, and nasociliary branches)
Oculomotor Nerve
Trochlear Nerve
Abducens Nerve
Superior and Inferior Ophthalmic Veins
Bony boundaries of inferior orbital fissure
Greater Wing of Sphenoid
Maxilla
Palatine Bones
Structures Passing Through the inferior orbital fissure
Zygomatic Nerve (branch of maxillary
division of trigeminal)
Infraorbital Nerve (branch of maxillary
division of trigeminal nerve)
Infraorbital Artery (branch of the
maxillary artery)
Infraorbital Vein (drains into pterygoid
plexus)
Branch of Inferior Ophthalmic Vein
Bony boundaries of supraorbital foramen
Frontal
Structures Passing Through the supraorbital foramen
Supraorbital Nerve (branch of
ophthalmic division of trigeminal)
Supraorbital Artery (branch of the
maxillary artery)
Supraorbital Vein (drains into
pterygoid plexus)
Bony boundaries of inferior groove and canal
Maxilla
Structures Passing Through the inferior groove and canal
Infraorbital Nerve (branch of ophthalmic
division of trigeminal)
Infraorbital Artery (branch of the maxillary
artery)
Infraorbital Vein (drains into pterygoid
plexus)
bony boundaries of zygomatic foramen
Zygomatic
Structures Passing Through the zygomatic foramen
Zygomaticotemporal Nerve (branch of
maxillary division of trigeminal)
Zygomaticofacial Nerve (branch of
maxillary division of trigeminal)
bony boundaries of nasolacrimal canal
Lacrimal
Structures Passing Through the nasolacrimal canal
Nasolacrimal Duct
bony boundaries of anterior ethmoidal foramen
Frontal
Ethmoid
Structures Passing Through the anterior ethmoidal foramen
Anterior Ethmoidal Nerve (branch of
ophthalmic division of trigeminal)
Anterior Ethmoidal Artery (branch of
ophthalmic artery)
Anterior Ethmoidal Vein (drains into
ophthalmic vein)
bony boundaries of posterior ethmoidal foramen
Frontal
Ethmoid
Structures Passing Through the posterior ethmoidal foramen
Posterior Ethmoidal Nerve (branch of
ophthalmic division of trigeminal)
Posterior Ethmoidal Artery (branch of
ophthalmic artery)
Posterior Ethmoidal Vein (drains into
ophthalmic vein)
OSTEOLOGY:
WALLS OF THE ORBIT
SUPERIORLY
Frontal (orbital plate)
Lesser wing of the sphenoid
STEOLOGY:
WALLS OF THE ORBIT
INFERIORLY
Maxilla
Zygomatic
Palatine (orbital process)
OSTEOLOGY:
WALLS OF THE ORBIT
MEDIALLY
Ethmoid (lamina papyracea)
Lacrimal
Sphenoid
Maxilla
OSTEOLOGY:
WALLS OF THE ORBIT
LATERALLY
Zygomatic
Greater wing of the sphenoid
A spherical globe with a diameter of approximately 2.5 cm that lies in the orbit’s anterior portion.
EYE
The eye is Surrounded by a thin capsule called the ______ (______):
•Provides support
•Allows for movement
fascia bulbi, Tenon’s capsule
The eye is Composed of 3 coats:
•______
•______
•______
Sclera, Uveal tract, Retina
what segment of the eye
Filled with aqueous humor
ANTERIOR SEGMENT
what segment of the eye
Separated into anterior and posterior chambers by the iris
ANTERIOR SEGMENT
what segment of the eye
Contains aqueous humor secreted by the ciliary body and drained through a trabeculated network eventually into the superior ophthalmic vein
ANTERIOR SEGMENT
what segment of the eye
Intraocular pressure is measured, normally 10 to 20 mm Hg
ANTERIOR SEGMENT
what segment of the eye
Filled with vitreous fluid
POSTERIOR SEGMENT
what segment of the eye
Called the vitreous cavity
POSTERIOR SEGMENT
The outermost layer, very fibrous
SCLERA
White along the periphery, except for the anterior portion –the cornea, which is transparent
SCLERA
Composed of choroid layer, ciliary body, and iris
UVEAL TRACT
The pigmented vascular layer between the sclera and the retina
Choroid
Extends posteriorly from the region of the optic nerve
anteriorly, where it is continuous with the ciliary body
near the ora serrata (anterior margin of the retina)
Choroid
Located between the choroid and the iris
Ciliary Body
Ring-shaped; has a series of transparent fibers that form the suspensory ligament of the lens
Ciliary Body
With in it is the ciliary muscle, which changes the shape of the lens
Ciliary Body
A thin disc like structure with a central opening–the pupil.
Iris
Separates the aqueous humor in to the anterior chamber (anterior to the iris) and the posterior chamber (between the iris and the lens).
Iris
Contains the sphincter and dilator pupillae muscles, which change the pupil’s shape in response to light.
Iris
Located posterior to the iris.
LENS
A transparent biconcave structure responsible for focusing.
LENS
Connected to the ciliary body by the suspensory ligaments.
LENS
The innermost coat of the eye.
RETINA
Thin and highly vascular.
RETINA
3 areas located on the retina’s posterior portion :
- ______
- ______
- ______
Optic disc, Macula lutea, Fovea centralis
Area where the optic nerve enters the retina is called the “blind spot”.
Optic Disc
Retina’s central artery enters the eye through the ______ and divides into superior and inferior branches.
optic disc
lateral to the optic disc
A depressed, yellow-appearing area that contains the fovea centralis in its center
Macula lutea
area of highest visual acuity and contains high concentration of cone photoreceptors.
Fovea Centralis
is the visual area seen by an eye at a given instant
FIELD OF VISION
is the area seen to the nasal side
NASAL FIELD
is the area seen to the lateral side
TEMPORAL FIELD
The ______ can be divided roughly into an old system to the midbrain and base of the forebrain and a new system for direct transmission of visual signals into the visual cortex located in the occipital lobes.
visual pathways
New System of Visual Pathway
- The visual nerve signals leave the retinas through the ______.
- At the ______, the optic nerve fibers from the nasal halves/field of the retinas cross to the opposite sides, where they join the fibers from the opposite temporal retinas to form the ______.
- The fibers of each optic tract then synapse in the ______.
- From there, geniculocalcarine fibers pass by way of the ______ (also called the geniculocalcarine tract) to the ______ in the calcarine fissure area of the medial occipital lobe.
optic nerves
optic chiasm, optic tracts
dorsal lateral geniculate nucleus of the thalamus
optic radiation, primary visual cortex
New System of Visual Pathway
The ______ lies in the calcarine fissure area, extending forward from the occipital pole on the medial aspect of each occipital cortex. This area is the terminus of direct visual signals from the eyes.
primary visual cortex
New System of Visual Pathway
The ______, also called visual association areas, lie lateral, anterior, superior, and inferior to the primary visual cortex. Secondary signals are transmitted to these areas for analysis of
visual meanings. It has different visual areas that
have specific designations.
Secondary Visual Areas of the Cortex
Old System of Visual Pathway
Visual fibers also pass to several older areas of the brain:
- from the optic tracts to the ______ of the hypothalamus, presumably to control circadian rhythms that synchronize various physiological changes of the body with night and day;
- into the ______ in the midbrain, to elicit reflex movements of the eyes to focus on objects of importance and to activate the pupillary light reflex;
- into the ______, to control rapid directional movements of the two eyes; and
- into the ______ of the thalamus and surrounding basal regions of the brain, presumably to help control some of the body’s behavioral functions.
suprachiasmatic nucleus
pretectal nuclei
superior colliculus
ventral lateral geniculate nucleus
In humans, the ______ is responsible for perception of virtually all aspects of visual form, colors, and other conscious vision.
Conversely, in many primitive animals, even visual form is detected by the ______, using the superior colliculus in the same manner that the visual cortex is used in mammals.
new system, older system
Perhaps the most important movements of the eyes are those that cause the eyes to “______” on a discrete portion of the field of vision.
fix
Fixation movements are controlled by two neuronal mechanisms: ______ and ______.
voluntary, involuntary
______ fixation mechanism — the mechanism that allows a person to move the eyes voluntarily to find the object on which he or she wants to fix the vision.
Voluntary
______ fixation mechanism — the mechanism that holds the eyes firmly on the object once it has been found.
Involuntary
To summarize, posterior “______” occipital cortical eye fields automatically “lock” the eyes on a given spot of the visual field and thereby prevent movement of the image across the retinas.
To unlock this visual fixation, voluntary signals must be transmitted from cortical “______” eye fields located in the frontal cortices.
involuntary, voluntary
In the same manner that a glass lens can focus an image on a sheet of paper, the lens system of the eye can focus an image on the retina. The image is ______ and ______ with respect to the object.
However, the mind perceives objects in the ______ position despite the upside-down orientation on the retina because the brain is trained to consider an inverted image as normal.
inverted, reversed, upright
Extrinsic muscles of the orbit
Levator palpebrae superioris
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique
INTRINSIC MUSCLES OF THE ORBIT
Ciliary
Sphincter pupillae
Dilator pupillae
Origin of Levator palpebrae superiors
Origin: Sphenoid (Lesser wing)
Insertion of Levator palpebrae superioris
Insertion: Skin of the upper eyelid
