Unit 4_Cranial Nerves Flashcards
How many paired cranial nerves arise directly from the brain and brainstem?
12 paired cranial nerves
Cranial nerves carry what primarily for the head/neck?
Carrying sensory, motor and autonomic information
What kind of nerves are cranial nerves, meaning damage to cranial nerve nuclei cause IPSILATERAL impairment?
peripheral nerves
Where does the Olfactory nerve originate?
on olfactory mucosa within the upper nasal cavity
Where do axons from the sensory nerves travel to synapse on the olfactory bulbs?
via olfactory nerves through the cribriform plate (Ethmoid bone)
Where does information from the olfactory bulbs travel, which run in the olfactory sulcus to the olfactory processing area in the temporal lobe?
via the olfactory tracts
What is the pathway of Cranial Nerve I – Olfactory Nerve?
Olfactory nerve –> Cribriform plate –> Olfactory bulbs –> Olfactory tracts –> Temporal lobe (Entorhinal Cortex)
What is a Cranial Nerve I – Olfactory Nerve Function and Lesion that occurs when there’s a loss of sense of smell? Impairment can be unilateral or bilateral depending on cause.
Anosmia
What is a Cranial Nerve I – Olfactory Nerve Clinical Disorders and Syndromes that occurs and is rarely noticeable clinically as the contralateral nostril compensates for loss?
Unilateral anosmia (ipsilateral)
What is a Cranial Nerve I – Olfactory Nerve Clinical Disorders and Syndromes that occurs and the first complaint is often the LOSS OF TASTE due to contribution of smell to detection of flavor?
Bilateral anosmia (bilateral involvement)
What are the following common causes for:
- Head trauma with injury to the ethmoid bone
- Conditions such as Parkinson’s, Alzheimer’s, and COVID
Cranial Nerve I – Olfactory Nerve Clinical Disorders and Syndromes
What cranial nerve is associated with visual information received in the retina, travels via the optic nerve to the primary visual cortex located in the occipital lobe?
Cranial Nerve II – Optic Nerve Location and Pathway
What is the pathway of Cranial Nerve II – Optic Nerve?
Optic nerve –> optic chiasm –> optic tract –> Lateral geniculate Nucleus of thalamus –> primary visual cortex (Occipital Lobe)
Where do we see partial crossing of the fibers (from nasal retina-peripheral vision) so that fibers from one hemiretina crosses to the contralateral optic tract?
at the optic chiasm
What sensory nerve is Cranial Nerve II – Optic Nerve associated with?
Vision
What is an inflammatory demyelinating condition of the optic nerve (CN II)? The primary sign of Multiple Sclerosis – blurred vision.
Optic neuritis
What cranial nerve is located in the upper midbrain?
Cranial Nerve III – Oculomotor Nerve
What kind of muscles originate in a tendinous ring at the orbital apex and insert on the sclera of the eye?
4 rectus muscles
2 oblique muscles
Extraocular muscles (CN III)
What muscle is responsible for lifting the eyelid as part of Cranial Nerve III – Oculomotor Nerve?
Levator Palpebrae
The Cranial Nerve III – Oculomotor Nerve handles muscle function to extraocular muscles, all eye movement with exception of what?
Abduction of the eye performed by lateral rectus (CN6)
Rotational movement of the eye performed by superior oblique (CN4)
What do parasympathetic fibers innervate the ciliary muscles of the lens of the eye for?
pupil constriction
What are the following symptoms of?
Ipsilateral eye will deviate laterally and inferiorly
Ptosis (droopy eyelid)
Dilated pupil (enlarged)
Symptoms of cranial nerve III -oculomotor nerve palsy
What is loss of innervation to Levator palpebrae muscle?
Ptosis (droopy eyelid)
What is loss of function to ciliary muscles that constrict the pupil?
Dilated pupil (enlarged)
What is the most common patient presentation of Cranial Nerve III – Oculomotor Nerve Clinical Disorders and Syndromes?
double vision (diplopia)
Common patient complaint – Dizziness!
What cranial nerve is located in the midbrain, has nerve fibers decussate (cross) in the midbrain just prior to exiting the brainstem, and is the smallest cranial nerve, but longest path?
Cranial Nerve IV – Trochlear Nerve
What cranial nerve motor function is to the Superior Oblique muscle (pulls the eye inferiorly and medially)?
Cranial Nerve IV – Trochlear Nerve