Cranial Nerve 2. Flashcards
How many layers make up the eye?
3
What are the layers of the eye?
- Fibrous Tunic
- Vascular Tunic
- Retina
What is everything in the Fibrous Tunic?
Sclera-white part
Cornea- clear; primary refractory structure
What is all in the Vascular Tunic?
- Ciliary body
- Iris
- Choroid
How many layers are in the Retina?
10
What are the layers of the Retina?
- Pigmented layer
- Photosensitive outer segment
- External limiting layer
- Outer nuclear layer
- Outer plexiform layer
- Inner nuclear layer
- Inner. Plexiform layer
- Ganglion layer
- Nerve fiber layer
- Internal limiting membrane
What layer is adjacent to the choroid
Pigmented layer
What layer has segments of rods and cones?
Photosensitive outer segments
What layer contains cell bodies of rods and cones?
Outer nuclear layer
What layer does rods and cones synapse with bipolar cells?
Outer plexiform layer
What layer contains cell bodies of bipolar cells
Inner nuclear layer
What layer has bipolar cells synapsids with ganglion cells?
Inner plexiform layer
What layer has ganglion cell bodies here?
Ganglion cell layer?
What layer is a glial boundary separating the Retina from the vitreous body?
Internal limiting membrane
True or False
The proximal end of the photoreceptor is either cylindrical or tapered?
False
Distal end
What is the other word for rod shaped?
Cylindrical
What is the other name for cone shaped?
Tapered
What are the three colors that cones receive?
Red, Green, and Blue
What do cones require to function at their best?
Require adequate light
True or False
Cones are most concentrated near the fovea
True
What is the job of rods
Sense light vs. dark
What area in the eye is completely composed of rods
Periphery of Retina
True or False
Rods are concentrated near center of fovea?
False
Where do polarized photoreceptors relay information?
To bipolar cells
Synapsing in outer plexiform layer
What does bipolar cells relay information to?
Ganglion cells
By synapsing in the inner plexiform layer
Nerves from nerve fiber layer relay information toward what structure?
Optic Disc
What nerve are axons carried in when they leave the eyeball?
Optic Nerve
What canal does the optic nerve travel thru when entering the skull?
Optic canal
When the 2 optic nerves unite what do they form?
Optic chiasma?
True or False
The optic nerve is myelinated.
True
What cells myelinated the optic nerve?
Interfasicular oligodendrocytes
In the optic chiasma what side of the Retina will cross?
Medial side
Nasal
In the optic chiasma what side of the Retina will not cross?
Lateral side
When the 2 optic nerves split up again they form what?
Optic tract
What structure does the optic tract travel around to get to one of the nuclei of termination?
Cerebral peduncles
What are the nuclei of termination for C.N.2?
- Lateral Geniculate Body
- Sup. Colliculus
- Pretectal nucleus of the midbrain
Where does the majority of the optic tract information go to terminate?
The lateral geniculate body
Where does the lateral geniculate body relay information to?
Cerebral cortex in the occipital lobe
What brdmn area does the lateral geniculate body send information to?
17
Where does the Sup. Collicus relay information to?
Tectospinal tract
What muscles are influenced by the tectospinal tract?
- SCM
2. Trapezius
Nuclei of termination is for sensory or motor
Sensory
Nuclei of origin is for sensory or motor?
Motor
Pretectal nuclues of the midbrain deal with what?
Light reflexes
How many neurons are in the C.N.2 pathway?
4
5 if counting the relay neuron
What the signs and symptoms associated with a lesion of the optic nerve?
Loss of depth perception
What are the signs and symptoms associated with a lesion of the optic chiasma?
Tunnel vision
What are the signs and symptoms associated with a lesion in the optic tract?
Loss of 1/2 the visual field
What is the process of the direct and consensual light reflex?
Shine light in one eye having a piece of paper at the bridge of their nose so other eye does not see this light
Ipsilateral eye constricts
Contralateral eye constricts (just not as much)
What is the accommodation reflex?
When you look at something near you like a book, then look up at something far away out a window
(Accomadation of near vision to far vision)
What is the process of the corneal reflex?
Use a cotton ball and touch the eye.
Patient should pull away
What is convergence?
Eyes both moving medially
