Cranial Nerves Flashcards
Which CN is in the ciribiform plate?
Olfactory (CN I)
Which CN is within the optic canal?
CN II (optic)
Which nerves pass through the superior orbital fissure?
CN III (oculomotor), IV (trochlear), V1 (opthalamic division of trigeminal), VI (abducens)
Which nerves pass through the foramen rotundum?
CN V2 (maxillary division of trigeminal)
Which CN pass through the foramen ovale?
CN V3 (mandibular division of trigeminal)
Which nerves pass through the internal acoustic meatus?
CN VII (facial) and CN VIII (vestibulocochlear)
Which CN pass through the jugular foramen?
CN IX (glossopharyngeal), X (vagus), IX (accessory)
Which CN passes though the hypoglossal canal?
CN XII (hypoglossal)
All sympathetic fibers in the head are what?
Postganglionic arising from the superior cervical ganglion of the sympathetic trunk They travel on vessels to the structures that they innervate (deep petrosal nerve)
Preganglionic parasympathetic fibers in the head arise from what?
Nuclei in the brain stem and synapse at 4 ganglia in the head (ciliary, pterygopalatine, otic and submandibular)
Which CNs carry preganglionic parasympathetics?
CN III, VII, IX and X
All postganglionic fibers in the head piggy back on a branch of what?
The trigeminal to arrive at the structure that they innervate
Which CNs are branchiomotor?
V, VII, IX, X and XI
What is the function of CN I (olfactory)?
Sensation of olfaction or smell Only type of nervous tissue to regenerate
What does damage to olfactory nerve cause?
Anosmia (partial or loss of smell)
What is the function of optic nerve (CN II)?
Special sensory: convey visual info from the retina
What is caused by damage to the optic nerve?
Anopsia (visual defects)
What is the pathway of the olfactory nerve?
Travels through the foramina in the cribiform plate of the ethmoid bone and synapses in the olfactory bulbs located in the anterior cranial fossa
What is the pathway of the optic nerve?
Enters cranium via optic foramen of sphenoid bone Left and right optic nerves unit at optic chains Optic tracts travel to lateral geniculate nucleus of thalamus Information is forwarded to the occipital lobe
What is the somatic motor/GSE function of the oculomotor nerve (CN III)?
To supply the levator palpebrae superioris, superior rectus, medial rectus, inferior rectus and inferior oblique muscles of the eye Supplies 4 extrinsic eye muscles
What is the visceral motor/GVE function of the oculomotor nerve?
Provides the parasympathetic supply to constrictor pupillae and ciliary muscles via the ciliary ganglion Contracts ciliary muscles to make the lens of eye more spherical (as needed for near vision)
What is the pathway of the oculomotor nerve?
Leaves cranium via superior orbital fissure and travels to eye and eyelid (parasympathetic fibers travel to ciliary ganglion and postganglionic parasympathetic fibers then travel to iris and ciliary muscle)
Which conditions are caused by damage to the oculomotor nerve?
Ptosis (upper eyelid droop), paralysis of eye muscles, leading to strabismus (eyes not in parallel/dedicated improperly), diplopia (double vision) and focusing difficulties
What is the function of the trochlear nerve (CN IV)?
To supply the superior oblique muscle of the eye that loops through a pulley shaped ligament to move eyeball inferiorly and laterally (down and out)
What is the pathway of the trochlear nerve?
Leaves cranium via superior orbital fissure and travels to superior oblique muscle
What conditions are caused by damage to the trochlear nerve?
Paralysis of superior oblique, leading to strabismus (eyes not in parallel/deviated improperly), diplopia (double vision)
What is the function of the abducens nerve (CN VI)?
To supply the lateral rectus muscle of the eye which abducts the eye (pulls away laterally)
What is the pathway of the abducens nerve?
Leaves cranium through superior orbital fissure and travels to lateral rectus muscle
What conditions are caused by damage to the abducens nerve?
Paralysis of the lateral rectus limiting lateral movement of the eye and diplopia (double vision)
What is right oculomotor nerve palsy?
Downward and outward gaze of the right eye Dilated pupil, ptosis
What is left abducent nerve palsy?
L eye does not abduct (cannot move eye outward/laterally)
What is the branchial motor/SVE function of the trigeminal nerve?
Innervate muscles of mastication, tensor tympani, tensor palatini, mylohyoid and anterior belly of digastric
What is the general sensory/GSA function of the trigeminal nerve?
From the face and scalp as far as the top of the head, conjunctiva, bulb of the eye, mucous membranes of paranasal sinuses, nasal and oral cavities including tongue and teeth, part of the external aspect of the TM, and fro the meninges of the anterior and middle cranial fossa
CN V1 conducts sensory impulses from what structures?
Cornea, nose, forehead and anterior scalp
CN V2 conducts sensory impulses from which structures?
Nasal mucosa, palate, gums and cheek
CN V3 conducts sensory impulses from which structures?
Anterior 2/3 of tongue, skin of chin, lower jaw, lower teeth, 1/3 from sensory fibers of auricle of ear
What are the three branches of the trigeminal nerve (CN V)?
Ophthalmic (VI), maxillary (V2) and mandibular (V3) which receive sensory impulses from face, oral cavity, nasal cavity, anterior scalp
What conditions are caused by damage to the trigeminal nerve?
Trigeminal neuralgia (tic douloureux) which is caused by inflammation of the sensory components of the trigeminal nerve and results in intense, pulsating pain lasting from minutes to several hours
What are the branches of the ophthalmic branch of CN V?
Lacrimal, frontal (supratrochlear and supraorbital), nasociliary (long and short ciliary, infratrochlear, ethmoidal) and meningeal branch nerves
What are the branches of the maxillary branch of CN V?
Zygomatic, Infraorbital, superior alveolar, palatine and meningeal nerves
What are the branches of the mandibular branch of CN V?
Buccal, lingual, inferior alveolar and auriculotemporal nerves
What are the brachiomotor branches of the mandibular nerve (V3)?
Medial ptergoid, lateral pterygoid, masseteric, deep temporal and mylohyoid nerves