Lecture 15 - Cranial Nerves Flashcards
collections of axons coming off the brainstem
cranial nerves
how many pairs of cranial nerves are there?
12
what type of neurons are the cranial nerves?
some pure motor, some pure sensory, others mixed
which of the cranial nerves are involved in parasympathetic stimulation?
III, VII, IX, and X
cell bodies of sensory neurons live in:
CN ganglia
the only cranial nerves that don’t come off the brainstem
I and II
cranial nerve I is called the:
olfactory nerve
what type of nerve is the olfactory nerve and what is its function?
pure sensory, responsible for sense of smell
sensory receptors in the roof of the nasal cavity
olfactory epithelium
olfactory nerve filaments supplies the:
olfactory epithelium
what is the path that sensory information follows through the olfactory nerve?
olfactory epithelium –> olfactory nerve –> olfactory bulb –> olfactory tract –> primary olfactory cortex
where is the primary olfactory cortex located?
the temporal lobe
the only sensory system to bypass the thalamus?
olfactory nerve system
damage or disease of the olfactory leads to:
hyposmia/anosmia (decreased ability to smell)
cranial nerve II is called the:
optic nerve
what type of nerve is the optic nerve and what is its function?
pure sensory, vision
what is the path that sensory information follows through the optic nerve?
retina –> axons of ganglion cells –> optic nerve –> optic chiasm –> optic tract –> lateral geniculate nucleus –> optic radiations –> primary visual cortex
what happens in the optic chiasm?
some sensory information crosses over to the contralateral side of the brain, some sensory information stays on the ipsolateral side
the lateral geniculate nucleus is part of the:
thalamus
the medial aspect of the occipital lobe on either side of the calcarine sulcus
primary visual cortex
how are visual fields projected onto the visual cortex?
in an inverted and reversed fashion
damage or disease of the optic nerve leads to:
visual field defects (ex: blindness)
cranial nerve III is called the:
oculomotor nerve
the oculomotor nerve comes off of the:
Midbrain
what type of nerve is the oculomotor nerve?
mixed nerve (somatic motor and parasympathetic)
the motor components of the oculomotor nerve control:
the medial rectus, superior rectus, inferior rectus, inferior oblique, and levator palpebrae superioris (all extra-ocular muscles except the lateral rectus and superior oblique)
the parasympathetic component of the oculomotor nerve controls:
pupillary constriction and accomodation of the lens
damage or disease of the oculomotor nerve leads to:
pupillary dilation (unopposed sympathetics) and ophthalamoplegia (eye movements weakened or paralyzed)
cranial nerve IV is called the:
trochlear nerve
what type of nerve is the trochlear nerve, and what is its function?
motor nerve, innervates the superior oblique muscle (in the eye)
comes off the back of the brainstem (midbrain) and wraps around to reach the superior oblique
trochlear nerve (CN IV)
ture or false: isolated damage of the troclear nerve is common
false
cranial nerve V is called the:
trigeminal nerve
what type of nerve is the trigeminal nerve?
mixed nerve (sensory and motor)
CN V has three branches arising from the trigeminal ganglion known as the:
- ophthalmic nerve (V1)
- maxillary nerve (V2)
- mandibular nerve (V3)
what is the function of the ophthalmic nerve (V1)?
receives sensory information from the eye and upper parts of the face
what is the function of the maxillary nerve (V2)?
receives sensory information from the cheek
what is the function of the mandibular nerve (V3)?
has both sensory and motor (chewing) innervation in the mandible