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The Orbit, Eye, and Lacrimal Apparatus
Eye, orbit, and lacrimal apparatus
49
Anatomy
Undergraduate 3
02/03/2014

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Cards

Term
What two things are located within the orbit?
Definition
1. The eye
2. The lacrimal apparatus
Term
Describe the shape of the orbit?
Definition
Similar to a circular pyramid
Term
What forms the base of the pyramid?
Definition
The upper, lower, medial and lateral borders of the orbit
Term
What makes up each border of the orbit?
Definition
1. Upper: the frontal bond
2. Medial: frontal bone, frontal eminence of maxilla, ethmoid and lacrimal bones
3. Lower: Maxilla and zygomatic bones (infraorbital margin)
4. Lateral: frontal process of zygomatic bone, and zygomatic process of frontal bone
Term
What makes up the roof, floor, medial and lateral walls of the orbit?
Definition
Roof: orbital plate of frontal bone
Floor: maxilla and zygomatic bones
Medial wall: frontal process of maxilla and lacrimal/ethmoid bones
Lateral wall: zygomatic bone and greater wing of sphenoid
Term
What are the 5 other features associated with the orbit?
Definition
1. Supra and infraorbital foramen
2. Optic canal
3. Superior and inferior optic fissures
Term
What is the organ of sight?
Definition
The eye
Term
What is the sensory component of the eye?
Definition
The retina
Term
How many layers, and cavities, are there in the eye? What separates the cavities?
Definition
3 layers, 2 channels; lens separates the compartments
Term
What is the function of the lens?
Definition
To focus light onto the retina
Term
Name the 3 layers of the eye, which is outermost and which is innermost
Definition
1. Cornea/Sclera - outermost
2. Choroid
3. Retina - innermost
Term
Which portion of the outer layer is anterior? Posterior?
Definition
Cornea = anterior clear portion, sclera = posterior white portion
Term
(T/F) The cornea has a smaller radius than the rest of the eye
Definition
True
Term
(T/F) These is innervation and blood supply to these layers
Definition
False
Term
What is contained within the choroid of the eye?
Definition
The blood supply to the eye
Term
What are the 4 prominent features of the choroid?
Definition
1. Blood supply
2. Pupil
3. Iris
4. Intraoccular muscles
Term
What is contained within the anterior portion of this layer? What is the function of this feature?
Definition
Pupil; opening that allows light into the eye
Term
(T/F) The retina is a complete layer
Definition
False, it is only on the posterior of the eye
Term
Describe its organization?
Definition
Ordered into 10 layers of rods and cones
Term
What is the macula lutea? Where is it found?
Definition
The most sensitive area of the eye; directly in line with the cornea and the lens, on the posterior of the eye
Term
What is the optic disc? Why does it exist?
Definition
The blind spot of the eye; it is where the nerve cells leave to join the optic nerve
Term
What nervous system controls the intraoccular eye muscles?
Definition
The ANS
Term
Name the 3 intraoccular muscles
Definition
1. Ciliary muscles
2. Sphincter pupillae
3. Dilator pupillae
Term
What is the function of the ciliary muscles?
Definition
Controls the thickness of the lens, therefore controlling its refractive power
Term
What is the function of the pupillae muscles?
Definition
Control the dilation of the pupil, therefore controlling the amount of light entering the eye
Term
Describe innervation of the cilliary muscles
Definition
PNS via CN III via ciliary ganglion
Term
Describe innervation of the sphincter pupillae
Definition
PNS via CN III via ciliary ganglion
Term
Describe innervation of the dilator pupillae
Definition
Sympathetic control
Term
Name the 7 extraoccular muscles
Definition
1. Superior, inferior, medial, and lateral rectae
2. Superior and inferior obliques
3. Levator papellbrae superioris
Term
What is the function of the LPS? What nerve innervates it?
Definition
Raises the eyelid; CN III
Term
Describe the origin, insertion, movement, and innervation of the superior rectus
Definition
O: Fibrous ring
I: Top of eye
F: Rotates eye upwards

Via CN III
Term
Describe the origin, insertion, movement, and innervation of the inferior rectus
Definition
O: Fibrous ring I: Bottom of eye F: Rotates eye downwards Via CN III
Term
Describe the origin, insertion, movement, and innervation of the medial rectus
Definition
O: Fibrous ring I: Medial side of eye F: Rotates eye medially Via CN III
Term
Describe the origin, insertion, movement, and innervation of the lateral rectus
Definition
O: Fibrous ring I: Lateral side of eye F: Rotates eye laterally Via CN VI
Term
Describe the origin, insertion, movement, and innervation of the superior oblique
Definition
O: Fibrous ring, through trochlea
I: Posterolateral superior surface of eye
F: Abducts and rotates eye downwards

Via CN IV
Term
Describe the origin, insertion, movement, and innervation of the inferior oblique
Definition
O: Middle of orbit floor
I: Posterolateral underside of eye
F: Abducts and rotates eye upwards

Via CN III
Term
What is the trochlea?
Definition
The "pulley" that the superior oblique runs through
Term
Describe sympathetic innervation of the eye, and what portions it controls
Definition
Controls: part of LPS, and the dilator pupillae
- Pregang leaves at T1, synapses in the superior cervical ganglion. Postgang fibres follow internal carotid to eventually reach their target
Term
Describe parasympathetic innervation of the eye, and what portions it controls
Definition
Controls: lacrimal gland and interior surface of eye (spincter and cilliary muscles)
- Lacrimal gland: CN VII synapse in the pterygopalantine ganglion, then travel to the lacrimal gland
- Eye muscles: CN III sends pregang to the ciliary ganglion, which then sends a subset of nerves to the sphincter muscles, while the rest goes to the ciliary muscles
Term
What are signs of inhibited SNS innervation of the eye
Definition
- Constricted pupil
- Droopy eyelid
Term
What are signs of inhibited PNS innervation of the eye
Definition
- Dilated pupil
Term
What is the conjunctiva?
Definition
The inner covering of the eyelids
Term
(T/F) It blends with the cornea
Definition
True
Term
What are the tarsal plates?
Definition
The thick fascial core of the eyelids
Term
What is the space between the eyelids called?
Definition
The Palpebral fissure
Term
Where are the lacrimal glands situated?
Definition
In the upper, outer orbit
Term
What structure do they connect to, and what does this allow?
Definition
Connect to the conjunctival sacs, which allows tears to enter the eye.
Term
What structure to the tears migrate to?
Definition
Migrate medially to the lacrimal duct
Term
What is the lacrimal punctum?
Definition
The structure that allows the tears to leave the eye and enter the lacrimal duct.
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