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Where do the cranial nerves emerge from and where do they go out to innervate?
Emerge from brainstem, innervate muscles of head and neck
Cranial nerves I and II arise from the ____.
Cranial nerves III and IV arise from the ___.
Cranial nerves V to XII arise from ___ and ___.
___ fiber cells in the motor cortex transmit impulses from the brain to tissue outside of the brain. ____ fiber cells in ganglia (collections) lie outside of the brain. They transmit impulses from sensory organs to the brain.
- Sensory (function like dorsal root ganglion)
Axons of the UMN bundle to form the ____ tract. They stop and synapse on the ___ in the brainstem which go out to control muscles of the head and neck.
- LMN (cranial nerves)
Other fibers the corticospinal tract synapse on ___ in the spinal cord.
CN I, the ___ nerve, is purely sensory and is exclusive involved in the sense of smell. Damage to this nerve will result in ___.
- Anosmia (partial or complete impairment in ability to smell)
Explain the process of the olfactory nerve.
Olfactory sensory receptors stimulated-->AP initiated in olfactory nerve-->synapse on sensory neurons in olfactory bulb-->back to cortex and other parts of CNS via the olfactory tract
This cranial nerve (CN II) carries sensory messages from the retina (arises from the back of the eye). Damage to this nerve will result in:
- Visual deficits that depend on the location of injury
After optic chiasm, fibers of the optic tract reach the occipital lobe via the ____.
This cranial nerve (CN III) is named the ___ nerve, and originates in the midbrain. It carries motor fibers to the ___ and ___ muscles and its sensory fibers carries proprioceptive feedback from these muscles to the brain. The main responsibility of this CN is:
- pupil constriction & movement of some eye muscles
Damage to the oculomotor nerve (CN III) will result in:
Ptosis (drooping of eye)
This cranial nerve (CN IV) is called the ___ nerve and it arises from the midbrain. It carries motor fibers to ___ and sensory fibers/proprioceptive feedback from these muscles to the brain. Contraction of these fibers cause the eye to move up and out
- extrinsic eye muscles
Damage to the trochlear nerve (CN IV) will result in:
Diplopia (double vision)
This cranial nerve (CN V), is named the ___ nerve. It is the largest CN. It carries sensory fibers from the __, __, __, and ___ via 3 divisions. The mandibular division contains ___ fibers which innervate muscles of ___. Give examples of these muscles.
- Face, nose, mouth, scalp
- mastication (masseter, digastric)
A unilateral LMN lesion to the trigeminal (CN V) nerve will result in:
Unilateral UMN lesion to CN V:
Bilateral UMN lesion to CN V:
- Jaw deviation to side of lesion (ipsilateral)
- No significant effect
- Significant limitation of jaw movements
This cranial nerve (CN VI), is called ___ and originates from the pons. It carries motor fibers to the ___ ___ and sensory fibers from this intrinsic muscle to the brain. Contraction of this muscle causes the eye to abduct/look away.
This cranial nerve, (CN VII), is called the ___ nerve. It carries sensory fibers of taste from the ___ 2/3 of the tongue and proprioceptive fibers from facial muscles. It also carries motor fibers to muscles of ___ ___ and some of the neck and stapedius.
- Facial nerve
- facial expression
Unilateral innervation of the Facial nerve (VII):
Bilateral innervation of the Facial nerve (VII):
Some of the things this nerve controls are:
- Lower face
- Upper face
- Forehead wrinkling, smiling, close eyes tightly, pulling larynx up and out
Damage to a LMN (after decussation) will result in asymmetry, atrophy of facial muscles, and drooping of eye, mouth, or nose.
Damage to an axon or LMN in the facial nerve (CN VII) will result in:
Lesion at or beyond the stylomastoid foramen will result in:
- Complete paralysis of all muscles of facial expression ipsilateral to the lesion
- Bell's palsy (complete paralysis on the whole side of face)
Damage to the UMN at the nuclei or axon of UMN results in paralysis of one part of the face, specifically the contralateral part of the ___ face. It is contralateral because lesion occurs before decussation. Bilateral innervation accounts for sparing of droopiness.
This cranial nerve (CN VIII), is called the __ nerve. It is responsible for sound and equilibrium. It carries messages for equilibrium from the ___ branch and semicircular canals. It carries impulses for hearing from the ___ branch. Damage will result in:
- Vestibulocochlear nerve
- Hearing loss & vertigo
This cranial nerve (CN IX) is called the ___ nerve. Its motor fibers originate in the medulla and carry fibers to the ___ muscle for swallowing and parasympathetic fibers to salivary glands. Sensory fibers carry messages from the pharynx, tonsils, and ___ 1/3 of tongue for taste and terminate in the medulla.
- Glossopharyngeal nerve
Damage to the (IX) glossopharyngeal nerve will result in:
- problems with swallowing
- numbness of ipsilateral pharynx
This cranial nerve (CN X) is called the __ nerve. Its motor fibers origniates from medulla and carries messages to the ___, ___, heart, and other visceral organs. It carries proprioceptive sensory messages from the neck, chest, and abdomen.
Damage to the vagus nerve (X) will result in:
- damage to vocal folds on affected side
- swallowing deficits (pharynx)
This cranial nerve (CN XI) is called the __ nerve. It is purely motor and provides motor stimulation to the ___ and ___ muscles via spinal fibers. Motor fibers from the medulla innervate the soft palate, __, and __ (__ root). It carries sensory fibers from these muscles to the brain.
- Accessory nerve
- sternocleidomastoid, trapezius
This cranial nerve (XII) is primarily motor and carries motor fibers to the ___ for speech and proprioceptive fibers from this muscle to the brain.
- Tongue deviation toward side of lesion (weaker side)
- Tongue deviation away from the side of the lesion
- Inability to protrude beyond lips
Atrophy & fasciculations
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