Cranial Nerves Flashcards
What are the 12 cranial nerves in order?
Olfactory (I), Optic (II), Oculomotor (III), Trochlear (IV), Trigeminal (V), Abducens (VI), Facial (VII), Vestibulocochlear (VIII), Glossopharyngeal (IX), Vagus (X), Accessory (XI), Hypoglossal (XII).
What is the function of the olfactory nerve (CN I)?
The olfactory nerve is responsible for the sense of smell.
What is the function of the optic nerve (CN II)?
The optic nerve transmits visual information from the retina to the brain.
What is the function of the oculomotor nerve (CN III)?
Controls most of the eye movements, pupillary constriction, and eyelid elevation.
What is the function of the trochlear nerve (CN IV)?
Innervates the superior oblique muscle, which moves the eye downward and inward.
What is the function of the trigeminal nerve (CN V)?
Provides sensory innervation to the face and motor control to the muscles of mastication.
What are the three branches of the trigeminal nerve?
Ophthalmic (V1), Maxillary (V2), Mandibular (V3).
What is the function of the abducens nerve (CN VI)?
Innervates the lateral rectus muscle, which abducts the eye.
What is the function of the facial nerve (CN VII)?
Controls muscles of facial expression, taste (anterior 2/3 of the tongue), salivation, and lacrimation.
What is the function of the vestibulocochlear nerve (CN VIII)?
Responsible for hearing and balance.
What is the function of the glossopharyngeal nerve (CN IX)?
Taste (posterior 1/3 of the tongue), swallowing, salivation, and monitoring carotid body/sinus.
What is the function of the vagus nerve (CN X)?
Autonomic control of the heart, lungs, digestion, and motor function in speech and swallowing.
What is the function of the accessory nerve (CN XI)?
Controls the sternocleidomastoid and trapezius muscles for head and shoulder movements.
What is the function of the hypoglossal nerve (CN XII)?
Controls tongue movements.
What is anosmia?
Loss of smell, which can result from CN I dysfunction.
What conditions can cause optic nerve (CN II) damage?
Stroke, demyelination (multiple sclerosis), tumors, and optic neuritis.
What is ptosis and which cranial nerve is responsible?
Drooping of the eyelid due to CN III dysfunction.
What is the clinical presentation of trochlear nerve (CN IV) palsy?
Vertical diplopia and head tilt away from the affected side.
What is trigeminal neuralgia?
Severe, recurrent facial pain along the trigeminal nerve distribution.
What is the corneal reflex and which cranial nerves are involved?
A protective reflex where touching the cornea causes blinking; CN V (afferent) and CN VII (efferent) are involved.
What is Bell’s palsy?
Idiopathic facial nerve (CN VII) paralysis causing unilateral facial drooping.
What is the Rinne test?
A test to differentiate conductive vs. sensorineural hearing loss using a tuning fork.
What is the Weber test?
A test where a tuning fork is placed on the forehead to assess hearing loss laterality.
What happens in a CN IX lesion?
Loss of gag reflex, impaired swallowing, and taste loss in the posterior 1/3 of the tongue.
What is uvula deviation in CN X lesion?
The uvula deviates away from the side of the lesion.
What is the role of the vagus nerve in the autonomic nervous system?
Regulates parasympathetic functions, including heart rate and digestion.
What is the effect of CN XI palsy?
Weakness in turning the head (sternocleidomastoid) and shoulder shrugging (trapezius).
What is tongue deviation in CN XII lesion?
The tongue deviates toward the side of the lesion when protruded.
Which cranial nerves are purely sensory?
CN I (Olfactory), CN II (Optic), CN VIII (Vestibulocochlear).
Which cranial nerves are purely motor?
CN III (Oculomotor), CN IV (Trochlear), CN VI (Abducens), CN XI (Accessory), CN XII (Hypoglossal).
Which cranial nerves are mixed (sensory and motor)?
CN V (Trigeminal), CN VII (Facial), CN IX (Glossopharyngeal), CN X (Vagus).
What are the autonomic functions of the cranial nerves?
CN III (pupillary constriction), CN VII (lacrimation and salivation), CN IX (salivation), CN X (parasympathetic control of heart and gut).
What is nystagmus and which cranial nerve is involved?
Involuntary eye movements, involving CN VIII.
What is diplopia?
Double vision, often due to dysfunction of CN III, IV, or VI.
What is Horner’s syndrome?
Ptosis, miosis, and anhidrosis due to sympathetic pathway disruption.
What is the function of the superior oblique muscle and which cranial nerve innervates it?
Depresses and abducts the eye, innervated by CN IV.
What is the function of the lateral rectus muscle and which cranial nerve innervates it?
Abducts the eye, innervated by CN VI.
What happens in an optic chiasm lesion?
Bitemporal hemianopia due to compression of crossing nasal retinal fibers.
What is the main blood supply to the cranial nerves?
Branches of the vertebrobasilar system and internal carotid arteries.
What is the function of the pupillary light reflex and which nerves are involved?
Constricts the pupil in response to light; CN II (afferent) and CN III (efferent).
What is dysarthria and which cranial nerves are involved?
Slurred speech due to CN V, VII, IX, X, or XII dysfunction.
Which cranial nerve is responsible for taste in the anterior 2/3 of the tongue?
CN VII (Facial nerve).
Which cranial nerve is responsible for taste in the posterior 1/3 of the tongue?
CN IX (Glossopharyngeal nerve).
Which cranial nerve innervates the parotid gland?
CN IX (Glossopharyngeal nerve).
What is trigeminal autonomic cephalalgia?
A group of severe unilateral headache disorders involving CN V.
What is the function of the spinal trigeminal nucleus?
Processes pain and temperature sensation from the face (CN V).
What is the function of the nucleus ambiguus?
Motor control of CN IX and CN X for swallowing and phonation.
What is the consequence of a lesion in the nucleus solitarius?
Loss of taste and autonomic dysfunction.
What is the function of the Edinger-Westphal nucleus?
Parasympathetic control of the pupil via CN III.
