CN 1 + 2 Flashcards
Cranial Nerve One
olfactory nerve
CN I: sensory or motor?
sensory
Where are olfactory neurons located?
olfactory epithelium lining superior part of the nasal cavity
Myelination status of olfactory neurons
unmyelinated, but cover by Schwann cells
Olfactory nerves pass through which bone to reach the olfactory bulb?
cribriform plate of the ethmoid bone
Secondary sensory neurons located in the olfactory bulb
mitral cells
Where are mitral cells located?
olfactory bulb
Olfactory nerves enter the bulb and synapse on mitral cells. What is the name of this synapse?
synaptic glomerulus
Mitral cells relay information _____(posterior or anterior) via the olfactory tract
posterior
Where does the olfactory tract split into medial and lateral olfactory striae?
anterior perforated substance
At the anterior perforated substance the olfactory splits into which two striae?
medial and lateral
What is the path of the medial olfactory striae?
cross midline at the anterior commissure and travel to the opposite olfactory bulb
Where do the lateral olfactory striae carry information?
primary olfactory cortex; the periamygdaloid and prepiriform area, including uncus(Bdmn 34)
Do we segregate smell?
no
Does the olfactory pathway synapse on the thalamus?
no
Automatic nerve from nasal septum
terminal nerve
Nerve important in tracking prey, poorly developed in humans
vomeronasal nerve
Loss of smell
anosmia
Cranial Nerve Two
optic nerve
Sensory organ of vision
eyes
Three tunics of the eye
1) fibrous tunic
2) vascular tunic
3) nervous tunic/retina
What makes up the fibrous tunic?
sclera and cornea
What makes up the vascular tunic?
ciliary body, iris, and choroid
How many layers makes up the nervous tunic/retina?
10 layers
Name the 10 layers of the nervous tunic/retina
1) pigmented layer
2) photosensitive outer segment
3) external limiting membrane
4) outer nuclear layer
5) outer plexiform layer
6) inner nuclear layer
7) inner plexiform layer
8) ganglion layer
9) nerve fiber layer
10) internal limiting membrane
In which layer of the nervous tunic/retina does a detached retina occur?
pigmented layer
Myelination status of the nerve fiber layer of the nervous tunic/retina
not myelinated
Three types of cones
red, green, and blue
In which layer of the nervous tunic/retina are the photoreceptors located?
outer segment
Point of clearest vision
fovea centralis
What to rod sense?
light and dark
Where are no rods found?
fovea centralis
Where is the greatest concentration of rods?
periphery of retina
Bipolar cell bodies are found in which layer?
inner nuclear
What layer is the synapse between bipolar cells and ganglion cells found?
inner plexiform
Are optic nerve axons myelinated?
yes (part of CNS)
What forms the myelin around the optic nerve axons?
interfascicular oligodendrocytes
In the optic chiasma fibers from the ____(medial or lateral) side of each retina cross, while _____(medial or lateral) fibers do not.
medial; lateral
3 nuclei of termination of the optic tract
1) lateral geniculate body
2) superior colliculus
3) pretectal nucleus of the midbrain
2 muscles influenced by the tectospinal tract
sternocleidomastoid and trapezius
Signs and symptoms associated with a lesion of the optic nerve
loss of vision in one eye and depth perception
Signs and symptoms associated with a lesion of the decussating fibers of the optic chiasma
tunnel vision (loss of peripheral vision in both eyes)
Signs and symptoms associated with a lesion of the optic tract
loss of 1/2 of the visual field opposite side of lesion
4 visual reflexes
1) direct and consensual light reflexes
2) accommodation reflex (near/far)
3) corneal reflex (CN V+VII)
4) convergence (medially turn eyes)
