Cranial Nerves Flashcards
What is cranial nerve I?
Olfactory - olfactory sense/smell
What is cranial nerve II?
Optic - optic sense/vision
What is cranial nerve III?
Oculomotor - motor to muscles that move eye
What is cranial nerve IV?
Trochlear - innervates one eyeball muscle whose tendon turns around a pulley (trochlea)
What is cranial nerve V?
Trigeminal nerve - has three major branches of “twin” nerves
What is cranial nerve VI?
Abducens - innervates the muscle that abducts the eyeball/pupil
What is cranial nerve VII?
Facial - innervates muscles of facial expression
What is cranial nerve VIII?
Vestibulocochlear - balance/sensing acceleration and hearing
What is cranial nerve IX?
Glossopharyngeal - mainly sensory to back of tongue and pharynx
What is cranial nerve X?
Vagus nerve - wide distribution in neck, thorax, and abdomen
What is cranial nerve XI?
Spinal accessory
What is cranial nerve XII?
Hypoglossal - motor to tongue (enters tongue from below)
What is the route of parasympathetic neurons through the cranial nerves?
They exit the brain and travel with cranial nerves III, VII, and IX (and also X), synapse in the parasympathetic ganglia, and then follow the trigeminal nerve (V) branches to their effector glands/tissues
What is the embryonic primordium of the olfactory nerve (I)?
Ectoderm of olfactory placode
What are the neuron components and function of the olfactory nerve (I)?
Special sensory neurons for smell (special visceral afferents)
What are the bony relations of the olfactory nerve (I)?
It lies on the cribiform plate of the ethmoid bone in the anterior cranial fossa
What is unique about the neuron cell bodies of the olfactory nerve (I)?
There are two sets of neuron cell bodies.
First set (olfactory nerve proper) sit at the top of the nasal cavity and pass through the cribiform plate to synapse in the olfactory bulb.
The second set (olfactory tract) meet the nerve proper synapses in the olfactory bulb and are surrounded by meninges and CSF
What is A?
Olfactory tract
What is B?
Olfactory Bulb
What is C?
Cribiform plate of ethmoid bone
What is D?
Olfactory nerves
What is E?
Frontal sinus
What is F?
Olfactory bulb
What is G?
Olfactory nerves
What is H?
Olfactory tract
What is I?
Sphenoid sinus
What is J?
Middle concha
What is the primordium of the optic nerve (II)?
Ectodermal optic cup (extension of the neural tube)
What are the neuron components/function of the optic nerve (II)?
Special sensory neurons for vision
What are the bony relations of the optic nerve (II)?
Passes through the optic canal in the lesser wing of the sphenoid bone (along side the ophthalmic artery) to enter the middl ecranial fossa where the optic chiasma is located
What eyeball structure is the optic nerve continuous with?
The retina lining the eyeball
What surrounds the optic nerve (II)?
CSF and meninges
What is a detached retina?
An injury that can be caused if a blow to the head causes the visual retina to fall away from the pigmented retina (they are not tightly fused)
What effect does a unilateral lesion anterior to the optic chiasma have on vision?
It causes vision loss in the eye on the side of the lesion
What effect does a unilateral lesion posterior to the optic chiasma have on vision?
It causes loss of vision in the left or right visual field that is sensed by the lateral retina of one eye and the medial retina of the opposite eye (each optic tract contributes to the field of vision of both eyes)
What is A?
Optic nerve
What is B?
Optic tract
What is C?
Optic chiasma
What is the primordium of the oculomotor nerve (III)?
Pre-otic somite
What are the neuron components of the oculomotor nerve (III)?
Somatomotor, presynaptic parasympathetic
What are the bony relations of the oculomotor nerve (III)?
Superior orbital fissure of the sphenoid bone
What are the functions of the somatomotor fibers of the oculomotor nerve (III)?
Eye movements and elevation of the upper eyelid (levator palpebrae superioris)
All extra-ocular eye movements except for two (lateral rectus - VI, superior oblique - IV)
What are the functions of the postsynaptic parasympathetic fibers of the oculomotor nerve (III)?
Controls smooth muscle in the cilliary body for close up vision and in the iris for pupil constriction
Where do the presynaptic parasympathetic fibers of the oculomotor nerve (III) synapse?
Ciliary ganglion
What is the primordium that the trochlear nerve (IV) is derived from?
Pre-otic somite
What are the neuron components of the trochlear nerve (IV)?
Somatomotor
What are the bony relations of the trochlear nerve (IV)?
Superior orbital fissure of sphenoid bone
What is the function of the trochlear nerve (IV)?
Help move the pupil down and out via the superior oblique muscle
What muscle is innervated by the trochlear nerve (IV)?
Superior oblique extraocular muscle
What is the primordium of the trigeminal nerve (V)?
Branchial arch 1 with maxillary and mandibular parts
Pretrematic branch relates to the ectoderm and head mesenchyme (from neural crest) of the frontonasal process
What are the neuron components of the trigeminal nerve (V)?
General sensory, branchiomotor, and parasympathetics (mostly postsynaptic)
Where are the general sensory cell bodies of the trigeminal nerve (V) located?
What is the relationship of parasympathetics to the trigeminal nerve (V)?
They travel to the ganglia via other cranial nerves, but they synapse in ganglia that are related to terminal branches of the trigeminal and then join the branches to the target tissues
What are the functions of the trigeminal nerve (V)?
General sensory (forehad, face, orbit, nasal cavity, oral cavity)
Branchiomotor (muscles of mastication)
Second half of parasympathetic pathway to lacrimal gland, nasal mucosa, and salivary glands (first half from nerve VII, then follows V2)
What are the three main divisions of the trigeminal?
Ophthalmic division (V1)
Maxillary division (V2)
Mandibular division (V3)
What is the pathway of V1?
The ophthalmic division (V1) passes through the superior orbital fissure and provides general sensory neurons to the derivatives of the frontonasal process (it is the pre-trematic branch of V)
What is the pathway of V2?
The maxillary division (V2) passes through the foramen rotundum in the greater wing of the sphenoid and then divides into branches in the pterygopalatine fossa.
What is the function of V1?
It provides general sensory neurons to derivatives of the frontonasal process (orbit, skin and superficial fascia of forehad, and external nose)
What is the function of V2?
It is sensory to the midface and upper jaw, nasal cavity, upper teeth, and palate
Parasympathetics join it from the facial nerve to supply the nasal mucosa and lacrimal gland
What is the pathway of V3?
The mandibular division passes through the foramen ovale)
What is the function of V3?
It provides general sensation to the oral cavity (except the palate), skin of jaw, and is branchiomotor to muscles of mastication
Parasympathetics from VII and IX join V3 to supply the submandibular, sublingual, and parotid salivary glands
What are the branches of V1?
Supraorbital (highest on forehead)
Supratrochlear (above eyebrow)
Lacrimal (lateral side of eyelid)
Nasocilliary (branches further into infratrochlear, external nasal, etc)
What are the branches of V2?
Infraorbital (below eye)
Zygomatic (temporal and facial branches above and below eye on lateral temple)
Greater palatine (in the mouth)
Lesser palatine (in the mouth to uvula/tonsils)
Superior alveolar (sinus mucosa)
What are the branches of V3?
Lingual (floor of mouth and back of tongue)
Inferior alveolar
Buccal (cutaneous jaw)
Ariculotemporal (lateral forehead)
Muscular branches
Mental (chin)
What is the embryonic primordium of the abducens nerve (VI)?
Pre-otic somitomere
What are the neuron components of the abducens nerve (VI)?
Somatomotor neurons
What are the bony relations of the abducens nerve (VI)?
Passes through the superior orbital fissure
What is the function of the abducens nerve (VI)?
Supplies the lateral rectus, which abducts the pupil
What are the embryonic primordium of the facial nerve (VII)?
Pharyngeal (branchial arch) #2
What are the neuron components of the facial nerve (VII)?
Branchiomotor, taste (special sensory), and presynaptic parasympathetics
Cell bodies for taste are in the geniculate ganglion
Taste and parasympathetic fibers run in a distinct root of VII (nervus intermedius)
What are the bony relations of the facial nerve (VII)?
Enters internal acoustic meatus of the petrous part of the temporal bone
Three major branches exit the temporal bone at the 1) stylomastoid foramen, 2) greater petrosal groove, 3) petrotympanic fissure
What are the functions of the facial nerve (VII)?
Branchiomotor to muscles of facial expressions
Taste to anterior 2/3 of tongue
Parasympathetics for lacrimal gland, nasal/palatal mucosa, submandibular/sublingual salivary glands
What is the embryonic primordium of vestibulocochlear nerve (VIII)?
Ectodermal otic placode that forms the inner ear
What are the neuron components of the vestibulocochlear nerve (VIII)?
Special sensory for hearing and balance
What are the bony relations of the vestibulocochlear nerve (VIII)?
Internal acoustic meatus of the petrous part of the temporal bone
What are the two components of the vestibulocochlear nerve (VIII)?
Vestibular (balance) and cochlear (hearing)
What is the embryonic primordium of the glossopharyngeal nerve (IX)?
Branchial arch 3
What are the neuron components of the glossopharyngeal nerve (IX)?
Branchiomotor to stylopharyngeus
Visceral sensory to pharynx (and posterior 1/3 of tongue)
Special sensory for taste to posterior 1/3 of tongue
Presynaptic parasympathetics destined for the parotid gland
Special sensory for baroreceptors in the carotid sinus at the beginning of the internal carotid artery
What are the bony relations of the glossopharyngeal nerve branches?
Exits the jugular canal with the internal jugular vein between occipital and temporal bones
Tympanic nerve re-enters the temporal bone to form a plexus on the walls of the middle ear cavity
Lesser petrosal nerve exits the bone in the lesser petrosal groove
Otic ganglion is close to the foramen ovale
What is the embryonic primordium of the vagus nerve (X)?
Pharyngeal arches 4 and 6
What are the neuron components of the vagus nerve (X)?
Branchiomotor to pharynx and larynx
Visceral sensory to larynx, airway, foregut and midgut caudal to the pharynx
Presynaptic parasympathetic to foregut and midgut
Special sensory (taste) to laryngopharynx
Special sensory to aortic arch and body (baro/chemoreceptors)
General sensory to external auditory meatus
What are the head-related functions of the vagus nerve (X)?
Controls mouth vs. nose breathing and pharyngeal perstalsis in swallowing
Controls vocal cord function in producing sounds, protecting the airway, and rasising airway pressure by closing the glottis
Initiates the cough reflex
What are the bony relations of the vagus nerve (X)?
Exits the jugular canal with nerves IX and XI and the internal jugular vein
What is the embryonic primordium of the spinal accessory nerve (XI)?
Somites near pharyngeal arch 6
What are the neuron components of the spinal accessory nerve (XI)?
Somatomotor + general sensory fibers supply the trapezius with sensory innervation
What are the bony relations of the spinal accessory nerve (XI)?
Enters the foramen magnum from the cervical spinal cord and then exits the jugular canal
What are the functions of the spinal accessory nerve (XI)?
Innervates the sternocleidomastoid and trapezius muscles
What types of actions can cause damage to the spinal accessory nerve (XI)?
Can be damaged with a blow to the side of the neck or traumatic lateral bending
What is the embryonic primordium of the hypoglossal nerve (XII)?
Post-otic somites
What are the nuron components fo the hypoglossal nerve (XII)?
Somatomotor to all intrinsic and extrinsic tongue muscles
What are the bony relations of the hypoglossal nerve (XII)?
Exits the hypoglossal canal of the occipital bone
What are the functions of the hypoglossal nerve (XII)?
All tongue movements
Which spinal nerves join the hypoglossal nerve (XII)?
C1 and C2
Which nerves pass through the superior orbital fissure?
Oculomotor (III)
Trochlear (V)
Trigeminal (V1)
Abducens (VI)
Which nerves pass through the internal acoustic meatus?
Facial (VII)
Vestibulocochlear (VIII)
Which nerves pass through the jugular canal?
Glossopharyngeal (IX)
Vagus (X)
Spinal accessory (XI)
What nerve is associated with branchial arch 1? What are the pretrematic branches?
Nerve: Trigeminal (V)
Pretrematic branch: Ophthalmic division (V1 to frontonasal process derivatives)
What nerve is associated with branchial arch 2? What are the pretrematic branches?
Nerve: Facial (VII)
Pretrematic branches: Chorda tympani - taste to anterior tongue
What nerve is associated with branchial arch 3? What are the pretrematic branches?
Nerve: Glossopharyngeal (IX)
Pretrematic branches: Tympanic nerve to middle ear
What nerve is associated with branchial arch 4/6?
Vagus nerve (X)
What is A?
Superior sagittal sinus
What is B?
Olfactory Bulb
What is C?
Olfactory tract
What is D?
Stalk of pituitary
What is E?
V1 branch of trigeminal
What is F?
V2 branch of trigeminal
What is G?
V3 branch of trigeminal
What is H?
Middle meningeal artery
What is I?
Trigeminal (V) ganglion nerves
What is J?
Facial (VII) and vestibulocochlear (VIII) nerve
What is K?
Glossopharyngeal (IX) nerve
What is L?
Vagus (X) nerve
What is M?
Superior petrosal sinus
What is N?
Sigmoid sinus
What is O?
Spinal accessory (XI) nerve
What is P?
Transverse sinus
What is Q?
Falx cerebri
What is R?
Superior sagittal sinus
What is S?
Tentorium cerebelli
What is T?
Spinal accessory (XI) nerve
What is U?
Hypoglossal (XII) nerve
What is V?
Vertebral artery
What is W?
Trigeminal (V) nerve
What is X?
Abducens (VI) nerve
What is Y?
Trochlear (IV) nerve
What is Z?
Basilar artery
What is 1?
Oculomotor (III) nerve
What is 2?
Internal carotid artery
What is 3?
Optic (II) nerve
What is 4?
Olfactory (I) nerve
A fracture of which of the following would diminish the sense of smell?
a) lesser wing of sphenoid bone
b) nasal bones
c) vomer
d) cribiform plate of ethmoid bone
e) frontal bone
d) cribiform plate of ethmoid bone
- olfactory nerves pass through the cribriform plate*
- a = optic nerve*
Which direction would the pupil remain in testing for oculomotor nerve function by asking the patient to try and move their pupil up and down, then in and out?
a) up and out
b) down and out
c) straight ahead
d) in and out
e) in and up
b) down and out
the abducens and trochlear nerve remain working –> abducens innervates lateral rectus (moves pupils out) and trochlear innervates superior oblique (moves pupils out and down)
A - lateral sides of both eyes with vision lost
fibers from the medial half of the retina cross at the optic chiasma (the parts that create vision in the lateral fields of vision)
In attempting a mandibular nerve block, a dentist inadvertently injects anesthetic into the parotid gland that extends around the posterior margin of the ramus of the mandible. The anesthetic is contained within the dense capsule of the gland. What function would be lost in this patient on the affected side?
a) hearing
b) sensation on the cheek
c) ability to close the eye
d) taste on the anterior 2/3 of the tongue
e) closing the jaw
c) ability to close the eye
- the facial nerve for the muscles of facial expression passes within the substance of the parotid gland - orbicularis oculi would be paralyzed*
- a = nerve VIII*
- b = infraorbital nerve (V2)*
- d = chorda tymani branch of facial nerve*
- e = mandibular branch of trigeminal nerve*
If a patient has hearing loss from a tumor in the internal acoustic meatus, what other nerve may be damaged?
a) facial
b) vagus
c) glossopharyngeal
d) accessory
e) maxillary
a) facial
- the facial nerve and nerve VIII pass into the internal acoustic meatus*
- nerve IX, X, and XI pass through jugular canal*
- maxillary passes through foramen rotundum*
Failure of migration of postotic (occipital) somites will result in which malformed muscle?
a) middle ear muscles
b) muscles of mastication
c) sternocleidomastoid muscles
d) muscles of facial expression
e) tongue muscles
e) tongue muscles
- a = arches 1 (tensor tympani) and 2 (stapedius)*
- b = arch 1*
- c = cervical somites*
- d = arch 2*
The sensory limb of the gag reflex is what nerve?
a) facial
b) glossopharyngeal
c) hypoglossal
d) vagus
e) lingual
b) glossopharyngeal
probing the back 1/3 of tongue initiates gag reflex, which gets visceral sensory innervations from IX (glossopharyngeal)
Disruption of the vagus nerve would impair speech, the cough reflex, and what other function?
a) hyoid bone movement
b) pharynx sensation
c) mandibular movement
d) swallowing
e) increasing intraoral pressure (e.g. blowing)
d) swallowing
vagus nerve is motor to pharyngeal constrictors and muscles of soft palate, all of which are involved in swallowing
What cranial nerve is often damaged because of its long course that takes it over the petrous part of the temporal bone?
a) abducens
b) ophthalmic nerve
c) oculomotor nerve
d) facial nerve
e) trochlear nerve
a) abducens
Damage to which of the following nerves results in dry nasal mucosa?
a) glossopharyngeal
b) oculomotor
c) maxillary nerve in foramen rotundum
d) facial nerve in the internal acoustic meatus
e) greater palatine nerve
d) facial nerve in the internal acoustic meatus
greater petrosal branch of facial nerve takes parasymapthetic fibers to the pterygopalatine ganglion and V2 branches to the nasal and palatal mucosa
