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
Damage to the nucleus of Cranial Nerve IV – Trochlear Nerve will cause what?
CONTRALATERAL Superior Oblique palsy
Contralateral eye may deviate ”up and out” as there are no opposing forces on the Inferior Oblique muscle
Damage to the Cranial Nerve IV – Trochlear Nerve AFTER it has left the brainstem will cause what?
IPSILATERAL palsy
What clinical disorder are the following signs/symptoms of?
May see head tilted AWAY from the side of the paralysis with chin tucked
- Helps to align visual fields
Most common patient presentation = double vision (diplopia)
- When looking down and in
Also – Dizziness!
Cranial Nerve IV – Trochlear Nerve
What cranial nerve is located in the pons, exits the brainstem ventrally at the pontomedullary junction?
Cranial Nerve VI – Abducens Nerve
What cranial nerve is the Motor Nerve to the Lateral Rectus Muscle and controls abduction of the eye?
Cranial Nerve VI – Abducens Nerve
Damage to the nucleus of Cranial Nerve VI – Abducens Nerve will cause what?
ipsilateral Lateral Rectus palsy
Ipsilateral eye will deviate medially
- no opposing forces on the Lateral rectus muscle
What is the most common patient complaint of Cranial Nerve VI – Abducens Nerve Clinical Disorders and Syndromes?
double vision (diplopia)
Also – Dizziness!
What are the 3 major branches of Cranial Nerve V – Trigeminal Nerve?
ophthalmic (V1)
maxillary (V2)
mandibular (V3)
What cranial nerve is located in the pons?
Cranial Nerve V – Trigeminal Nerve
What cranial nerve provides sensory to the face and anterior 2/3 of the tongue, and touch, pain, temp, joint position and vibration?
Cranial Nerve V – Trigeminal Nerve
What cranial nerve provides motor to the muscles of mastication, including the masseter, temporalis, medial and lateral pterygoid muscles and the motor root from mandibular division?
Cranial Nerve V – Trigeminal Nerve
What cranial nerve provides sensory input for corneal reflex?
Cranial Nerve V – Trigeminal Nerve
Impaired sensation to ipsilateral side of the face presents as what?
Cranial Nerve V – Trigeminal Nerve Lesion Presentation
Loss of motor to ipsilateral muscles of mastication, including difficulty chewing, swallowing presents as what?
Cranial Nerve V – Trigeminal Nerve Lesion Presentation
Impaired corneal reflex presents as what?
Cranial Nerve V – Trigeminal Nerve Lesion Presentation
What Cranial Nerve V – Trigeminal Nerve Clinical Disorders and Syndromes is the following:
Categorized by brief episodes of severe pain
Most common in V2 and V3 distributions
Cause generally unknown, can be present in MS with demyelination of trigeminal nerve
Trigeminal neuralgia
What cranial nerve is the following:
Sits in the pons
Exits the brainstem at the pontomedullary junction
Branches into 5 motor segments:
Temporal
Zygomatic
Buccal
Mandibular
Cervical
Cranial Nerve VII – Facial Nerve
What cranial nerve includes the following:
Special sense of taste to the anterior 2/3 of the tongue
Motor to the muscles of facial expression
Motor to stapedius
Along with tensor tympani [CN5], works to dampen movements of the inner ear ossicles for modulation of acoustic signal intensity
Parasympathetic to the lacrimal glands
Both SENSORY AND MOTOR
Cranial Nerve VII – Facial Nerve
What cranial nerve is the following motor function associated with:
Temporal branch
- Frontalis
- **Orbicularis Oculi
- Corrugator supercilii
Zygomatic branch
Buccal branch
Marginal Mandibular branch
Cervical branch
Cranial Nerve VII – Facial Nerve
Loss of motor to the contralateral lower face involves what neuron?
- Unilateral cortical lesion (or corticobulbar lesion) usually spare the forehead because of bilateral innervation from bilateral motor cortices
UMN
Ipsilateral loss of motor to the whole face (Bell’s Palsy) involves what neuron?
- Loss of corneal blink reflex due to damaged motor output
- CN 5, 7
LMN
What Cranial Nerve VII – Facial Nerve Clinical Disorders and Syndromes usually has a viral cause, impairment to all divisions of the facial nerve?
Gradually recover, usually prescribed steroid
Symptoms:
Unilateral facial weakness
Inability to close eyelid
Dry eye due to lacrimal gland impairment
Bell’s Palsy
What cranial nerve involves the vestibular nerve, which exits the brainstem at the pontomedullary junction, lateral to the facial nerve?
2 Divisions:
Vestibular
Cochlear
Cranial Nerve VIII – Vestibulocochlear Nerve
What cranial nerve is a sensory nerve and involves the special sense of hearing?
Vestibular nuclei plays an important role in adjustment of posture, muscle tone, eye and head position.
Cranial Nerve VIII – Vestibulocochlear Nerve
What cranial nerve involves unilateral hearing loss?
Sx: dizziness and imbalance – need further testing to determine peripheral vs central dizziness and etiology within vestibular system
- Abnormal Nystagmus
Differentiate between Sensorineural and Conductive hearing loss with Rinne’s Test
Cranial Nerve VIII – Vestibulocochlear Nerve
What cranial nerve originates in the medulla oblongata of the brainstem? Exits the brainstem at the ventrolateral Medulla.
Cranial Nerve IX – Glossopharyngeal Nerve
What cranial nerve involves the following:
Sensory: to the posterior 1/3 tongue and pharynx, general sensation to the carotid body
Motor: supplies stylopharyngeus muscle
Elevates the pharynx during talking and swallowing
Contributes to the gag reflex with CN 10 (vagus)
Parasympathetic: assist with parotid gland function (secrete saliva to facilitate chewing, swallowing, etc.
Cranial Nerve IX – Glossopharyngeal Nerve
What cranial nerve presents as the following when there’s a lesion present?
Impaired sensation to the posterior 1/3 tongue, pharynx, and palate (impaired taste)
Difficulty swallowing (ipsilateral stylopharyngeus)
Impaired gag reflex
Cranial Nerve IX – Glossopharyngeal Nerve
What cranial nerve involves the following:
More likely to be a central lesion than peripheral lesion.
However, peripheral lesions can be caused by demyelinating diseases, diabetic neuropathy, surgical damage with head/neck surgeries.
Ask the patient to say ’Ahh’ – look for uvula elevation and symmetrical palate movements
Cranial Nerve IX – Glossopharyngeal Nerve
What cranial nerve is the “Wandering nerve” and exits the brainstem at the Medulla?
Cranial Nerve X – Vagus Nerve
What cranial nerve involves the following:
Parasympathetic: function to heart, lungs, digestive tract down to the splenic fissure
REST and DIGEST
Brachial motor: pharyngeal muscles (swallowing) and laryngeal muscles (voice box)
Sensory: special sense of taste from pharynx and epiglottis, chemo and baroreceptors of the aortic arch
Cranial Nerve X – Vagus Nerve
What cranial nerve involves the following clinical disorders and syndromes:
Postural Orthostatic Tachycardia Syndrome (POTS)
- Abnormal blood pressure and heartrate response to activity, positioning, and even rest
Vasovagal Syncope
Digestive disorders (gut-brain axis)
Cranial Nerve X – Vagus Nerve
What cranial nerve arises from the upper 6 segments of the cervical spinal cord?
Cranial Nerve XI – Spinal Accessory Nerve
What cranial nerve involves the following nerve function:
MOTOR NERVE to sternocleidomastoid and trapezius muscle
- Sternocleidomastoid (SCM): tilt head to ipsilateral side; rotate to contralateral side
- Trapezius: elevates shoulders
Cranial Nerve XI – Spinal Accessory Nerve
What cranial nerve involves the following when a lesion is present:
Ipsilateral weakness with shoulder shrug
Weakness of head turn AWAY from lesion
Cranial Nerve XI – Spinal Accessory Nerve
What cranial nerve involves impairment commonly caused by:
- Trauma (particularly to cervical spine)
- Surgical procedures
- Lymph node removal/biopsy
Cranial Nerve XI – Spinal Accessory Nerve
What cranial nerve exits the brainstem at the ventral medulla between the pyramid and inferior olivary nucleus? Exits through hypoglossal foramen.
Cranial Nerve XII – Hypoglossal Nerve
What cranial nerve involves MOTOR NERVE to muscles of the tongue?
Cranial Nerve XII – Hypoglossal Nerve
What causes CONTRALATERAL tongue weakness involving the Corticobulbar tract and Primary motor cortex?
Cranial Nerve XII – Hypoglossal NerveLesion Presentation
What cause IPSILATERAL tongue weakness?
Cranial Nerve XII – Hypoglossal NerveLesion Presentation
What cause tongue muscles are protrusion muscles, so will see tongue deviate TOWARD the weakness?
Cranial Nerve XII – Hypoglossal NerveLesion Presentation
