Quiz I: CN I and II Flashcards
First order neurons of CN I (primary sensory neurons) are called what?
Olfactory neurons (bipolar cells)
Where are Olfactory Neurons located?
Olfactory epithelium lining superior part of the nasal cavity.
What covers the olfactory epithelium?
A thin layer of mucus.
What cells support the olfactory neurons?
“Supporting Cells”
What do olfactory “hairs” function as?
Receptors
Central processes (axons) collected into 10 to 20 olfactory nerves convey information to what?
Olfactory bulbs
Are Olfactory neuron axons myelinated?
No, however they are covered by Schwann cells
What bony feature do olfactory nerves pass through, and what bone is this feature found on?
- ) Cribriform Plate
2. ) Ethmoid bone
The olfactory nerves enter the olfactory bulb and synapse on dendrites of ____________ cells.
Mitral cells
_________ ___________ are formed at the synapses in the olfactory bulb.
Synaptic Glomeruli
What are the secondary sensory neurons of CN I called?
Mitral Cells
Where are mitral cell bodies located?
Olfactory Bulb
Where do mitral cells relay information?
Posterior via the olfactory tract
At the anterior perforated substance, the olfactory tract fibers split into medial and Lateral ______ ______.
Medial and Lateral Olfactory Striae
Medial stria fibers cross the midline via the ________ ___________ and travel to the opposite olfactory bulb.
Anterior Commissure
Lateral stria fibers carry information where? (3 places)
- ) Primary Olfactory Cortex
- ) Periamygdaloid Area
- ) Prepiriform Area (including the Uncus/ BM Area 34) on the medial aspect of the temporal lobe.
T/F Each nostril sends info to both hemispheres?
True
T/F Each hemisphere receives info from both nostrils?
True
T/F The Mitral cell synapses at the Thalamus.
False, nowhere in this pathway does synapse occur at the thalamus.
What is the loss of smell called?
Anosmia, this condition is rare
How can skull fractures lead to smell deficits?
Skull fractures can lead to damage of C.N. I, especially if the ethmoid is involved.
How can you determine CSF leakage with a patient?
Presents differently on paper (tissue paper), halo sign will form if CSF is present as the mucus separates from CSF.
What pathway travels from the nasal septum and is autonomic?
Terminal nerve
What pathway is poorly developed in humans but well developed in animals that track their prey?
Vomeronasal Nerve
What is the sensory organ of vision?
The Eye
How many layers is the eye composed of?
3
What is the outermost layer of the eye called?
Fibrous Tunic
What does the Fibrous Tunic consist of? (2 parts)
Sclera (white part) and Cornea (clear part)
What is the middle layer of the eye called?
Vascular Tunic
What does the Vascular Tunic consist of? (3 parts)
Ciliary Body, Iris (Colored part) and Choroid
What is the innermost layer of the eye called?
Retina
How many layers does the Retina Consist of?
10
What is the innermost layer of the Retina, adjacent to the Choroid?
Pigmented layer
What specific layer of the retina actually detaches when a patient is experiencing a detached retina?
The pigmented layer detaches from the choroid.
What is the second layer of the Retina (from External to Internal)?
Photosensitive outer segments of rods and cones.
What is the third layer of the Retina (from External to Internal)?
External limiting membrane
What is the fourth layer of the Retina (from External to Internal)?
Outer Nuclear Layer (contains rod and cone cell bodies)
What is the fifth layer of the Retina (from External to Internal)?
Outer Plexiform Layer (Rods and Cones synapse with bipolar cells here)
What is the sixth layer of the Retina (from External to Internal)?
Inner Nuclear Layer (Contains cell bodies of bipolar cells)
What is the seventh layer of the Retina (from External to Internal)?
Inner Plexiform Layer (Bipolar cells synapse with ganglion cells here)
What is the eighth layer of the Retina (from External to Internal)?
Ganglion cell Layer (Ganglion cell bodies)
What is the ninth layer of the Retina (from External to Internal)?
Nerve Fiber Layer (Retina ganglion cell axons are found here)
Are Retina Ganglion cells axons myelinated?
No
What is the tenth layer of the Retina (Innermost Layer)?
Internal Limiting Membrane
What is a glial boundary separating the retina from the vitreous body?
The Internal Limiting Membrane
What is the distal end of a photoreceptor called?
The Outer Segment
Is the distal end of the photoreceptor closer to or further away from the choroid when compared with Rod and Cone Cell Bodies?
The distal end is closer to the Choroid than the cell bodies of the Rods and Cones
What photoreceptor is Cylindrical?
Rod
What photoreceptor is Tapered?
Cone
What are the three types of Cones?
Red, Green, Blue
What is the fovea centralis almost entirely composed of?
Cones
What do the cones require to function best?
Adequate Light
Where are the cones concentrated toward in the retina?
Toward the Center
What do rods sense?
Light vs. Dark
Are rods used to visualize objects clearly?
No, they are used for B&W vision and to visualize textures.
Where are rods rarely found?
In the Fovea Centralis
Where are rods usually found?
Periphery of Retina (almost entirely rods)
T/F Most forms of color blindness are sex-linked?
True
When depolarized, photoreceptors relay information to bipolar cells by synapsing in which layer?
Outer Plexiform Layer
Bipolar Cell Bodies are found in which layer?
Inner Nuclear Layer
Bipolar cells relay info to _________ cells.
Ganglion
Where do Bipolar cells relay info to ganglion cells?
Inner Plexiform Layer
Axons from ganglion cells are conveyed in the nerve fiber layer to the _______ _____.
Optic Disc
Is the Nerve Fiber Layer myelinated?
No
After leaving the eyeball, axons are carried in the ________ _______.
Optic Nerve
The optic nerves enter the skull through the ______ ______ and unite to form the ________ ________.
- ) Optic Canal
2. ) Optic Chiasma
Are Optic Nerve axons myelinated?
Yes
What cells form the myelin on the optic nerve?
Interfasicular Oligodendrocytes
T/F In the Optic chiasma the medial fibers cross.
True
T/F In the Optic chiasma the lateral fibers cross.
False
The Medial and Lateral fibers of the Optic Chiasma split to form the ______ ______.
Optic Tracts
The Optic tract travels around what?
Cerebral Peduncles
The optic tract fibers synapse on what?
On (one of three) nuclei of termination
What are the three nuclei of termination?
- ) Lateral Geniculate Body
- ) Superior Colliculus
- ) Pretectal Nucleus of Midbrain
Where do the majority of optic tract fibers synapse?
Lateral Geniculate Body (Nucleus of termination)
Where does the Lateral Geniculate Body relay info?
Cerebral Cortex in the Occipital Lobe
Where does the Superior Colliculus relay info?
Tectospinal Tract
What two muscles are influenced by the tectospinal tract?
SCM and Trapezius
What are the four (five) neurons in the pathway for vision?
- ) Rod/Cone
- ) Bipolar Cell
- ) Ganglion Cell
- ) Neuron from Lateral Geniculate Body to Occipital Lobe
* 5.) Cell (including cell body) in the Cerebral Cortex
*This is sometimes included in varying sources
What happens when a lesion occurs to the optic nerve?
You lose vision in one eye completely.
What happens when a lesion occurs to the decussating fibers in the optic chiasma?
You lose peripheral visual field (tunnel vision)
What happens when a lesion occurs in the optic tract?
You lose a side of your visual field (either entire right side is lost, or entire left side is lost)
Where does the neuron relayed to the occipital lobe specifically synapse?
BM Area 17 along calcarine sulcus
What does the pretectal nucleus of the brain deal with?
Light Reflexes
What happens with a direct reflex of the pupil?
Constriction
What happens with an indirect reflex of the pupil?
Constriction to a lesser extent
Is CN II responsible for the motor aspect of light reflexes?
No, it is a purely sensory CN. (There are more to these light reflexes than just CN II)
What is the term for transitioning from focusing on something far away to something close?
Accommodation Reflex
What happens to the lens when looking at something close up?
It becomes more convex.
What is the term for when something lightly touches the cornea, followed by that person blinking and pulling their cornea away quickly?
Corneal Reflex
What is the term for when the medial rectus is active on both sides to look at the tip of the nose?
Convergence
Can most people diverge their eyes?
No