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78 Cards in this Set

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What is the primary function of CN I?
Olfactory

Sensory:
- Olfaction
What is the primary function of CN II?
Optic

Sensory:
- Vision
What is the primary function of CN III?
Oculomotor

Motor:
- Most extraocular muscles
- Lid elevation
- Pupil constriction
What is the primary function of CN IV?
Trochlear

Motor:
- Superior oblique muscle of the eye (intorsion)
What is the primary function of CN V?
Trigeminal

Senosry:
- Facial sensation

Motor:
- Muscles of mastication
What is the primary function of CN VI?
Abducens

Motor:
- Lateral rectus muscle of the eye (abduction)
What is the primary function of CN VII?
Facial

Sensory:
- Taste

Motor:
- Muscles of facial expression
- Secretion of lacrimal gland
- Secretion of salivary glands (except parotid)
What is the primary function of CN VIII?
Vestibulocochlear

Sensory:
- Hearing
- Equilibrium (proprioception)
What is the primary function of CN IX?
Glossopharyngeal

Sensory:
- Taste

Motor:
- Stylopharyngeus muscle
- Carotid body reflexes
- Secretion of the parotid gland
What is the primary function of CN X?
Vagus

Sensory:
- Aortic arch reflexes
- Inputs from viscera to control cardiac, respiratory, and digestive functions
- Parasympathetic outflow for thoracic and abdominal viscera

Motor:
- Most muscles of the pharynx
- Most muscles of the larynx
What is the primary function of CN XI?
Spinal Accessory

Motor:
- Sternocleidomastoid
- Upper trapezius
What is the primary function of CN XII?
Hypoglossal

Motor:
- Tongue muscles
Where are the cell bodies of preganglionic sympathetic fibers to the head and face found and where do their axons travel?
Upper thoracic spinal cord

Axons travel by ventral roots to spinal nerves and then to the sympathetic trunk

Most ascend in the trunk to the superior cervical ganglion
How do postganglionic sympathetic fibers travel after the cervical ganglion?
Travel in plexuses along the walls of the external or internal carotid arteries
What are the targets of the postganglionic sympathetic fibers in the head and face?
Cutaneous arteries

Sweat glands

Pupillary dilator muscle

Smooth muscle that elevates the eyelid
What can interruption of the sympathetic pathway to the head and face cause?
Horner's syndrome:
- Ptosis
- Miosis
- Anhidriosis
What are the three areas of the brain stem?
Medulla
- Contiguous with the cervical spinal cord

Pons
- Largest part of the brain stem

Midbrain
- Most rostral portion of brain stem
Where is cerebrospinal fluid (CSF) made?
Choroid plexus in the ventricles
What is the path of CSF flow?
3rd ventricle of the diencephalon through the cerebral aqueduct of the midbrain and the widened 4th ventricle of the pons and rostral medulla

Then to the subarachnoid space through apertures
What cranial nerves are attached to the forebrain?
CN I

CN II
What cranial nerves are attached to the brainstem?
CN III - X

CN XII
Describe the path of CN XI
Spinal accessory nerve

Originates from the upper cervical spinal cord

Enters the skull through the foramen magnum

Exits the skull through the jugular foramen (along with CN IX and CN X)
Where does CN I enter the skull?
Olfactory

Cribriform plate
Where does CN II enter the skull?
Optic

Optic canal
Where does CN III enter the skull?
Oculomotor

Superior orbital fissure
Where does CN IV enter the skull?
Trochlear

Superior orbital fissure
Where do the branches of CN V enter the skull?
Trigeminal

V1: Opthalmic division
- Superior orbital fissure
V2: Maxillary division
- Foramen Rotundem
V3: Mandibular division
- Foramen ovale
Where does CN VI enter the skull?
Abducens

Superior orbital fissure
Where does CN VII enter the skull and how does it travel through the skull?
Facial

Enters skull through internal auditory meatus

Exits skull through stylomastoid foramen
Where does CN VIII enter the skull?
Vestibulocochlear

Internal auditory meatus
Where does CN VIII enter the skull?
Vestibulocochlear

Internal auditory meatus
Where does CN IX enter the skull?
Glossopharyngeal

Jugular foramen
Where does CN X enter the skull?
Vagus

Jugular foramen
Where does CN XI enter the skull?
Spinal accessory

Jugular foramen
(Enters skull through foramen magnum)
Where are the sensory ganglia that contribute sensory fibers to the head and neck located?
Swellings along the nerves in the peripheral nervous system

(Equivalent of dorsal root ganglia of spinal nerves)
What are the three categories of cranial nerve sensory fibers and what information do they convey?
Somatic sensory
- Touch
- Pain
- Temperature
- Proprioception of face, meninges, sinuses

Visceral sensory
- Taste
- Inputs from viscera for control of cardiac, respiratory, and digestive functions

Special sensory
- Hearing
- Vestibular sensation
Where are the cell bodies of cranial nerve motor fibers located?
Within the brain stem
- Called the "cranial nerve motor nuclei of the brain stem"

The exception is the spinal accessory nerve
What are the three categories of cranial nerve motor fibers and what do they do?
Somatic motor
- Extraocular muscles
- Intrinsic tongue muscles

Branchial motor
- Muscles of mastication
- Facial expression
- Pharynx
- Larynx
- Middle ear

Parasympathetic
- Parasympathetic ganglia in the head
- Parasympathetic ganglia near the thoracoabdominal viscera proximal to the splenic flexure
What are the 4 parasympathetic ganglia in the head and from where do they receive their input?
Ciliary
- Input from CN III

Pterygopalatine
- Input from CN VII

Submandibular
- Input from CN VII

Otic
- Input from CN IX
What cranial nerves have only somatic motor axons?
CN III - Oculomoter

CN IV - Trochlear

CN VI - Abducens

CN XII - Hypoglossal
What cranial nerves have only special sensory fibers?
CN I - Olfactory

CN II - Optic

CN VIII - Vestibulocochlear
What cranial nerves have more than two categories of fibers?
CN V - Trigeminal

CN VII - Facial

CN IX - Glossopharyngeal

CN X - Vagus
What skeletal muscles are innervated /by CN XI (spinal accessory)
Sternocleidomastoid

Upper part of trapezius
Describe the path of CN I (olfactory)
From: olfactory epithelium in nasal cavity

Through: Cribriform plate

To: olfactory bulbs

(Then the post-olfactory bulbs travel to higher cortical centers)
Describe the path of CN II (optic)
From: retina

Through: Optic canal

To:
What is the difference between the optic nerves and the optic tracts?
Optic nerve: CN II (optic) fibers before they cross the optic chiasm

Optic tract: CN II (optic) fibers after they cross the optic chiasm
What muscles are and are not innervated by CN III (oculomotor) innervate?
Innervated:
- Superior rectus
- Medial rectus
- Inferior rectus
- Inferior oblique
- Levator palpebrae superioris

Not innervated:
- Superior oblique (CN IV)
- Lateral rectus (CN VI)
What happens with a unilateral lesion of CN III (oculomotor)?
Diplopia (double vision)

Down and out:
- Innervated extraocular muscles are unopposed by the lateral rectus and superior oblique

Unilateral ptosis
- Dysfunctional levator palpebrae superioris
Describe the parasympathetic pathway of CN III (oculomotor) fibers
Preganglionic parasympathetic fibers → Ciliary ganglion (in orbit) → Pupil constrictor and ciliary muscles
What will happen to the pupil on the ipsilateral side of a CN III (oculomotor) lesion?
Pupil will be larger

Pupil will not respond to light
Describe the path of CN III (oculomotor)
From: Ventral surface of midbrain

Through: Superior orbital fissure

To: Superior rectus, Medial rectus, Inferior rectus, Inferior oblique, Levator palpebrae superioris
Describe the path of CN IV (trochlear)
From: Dorsal surface of brain stem (near junction of pons and midbrain)

Through:
- Around brain stem
- Along lateral wall of cavernous sinus
- Through superior orbital fissure on OPPOSITE side

To: Superior oblique
What does the superior oblique muscle do?
Depression of eye

Intorsion of eye
What can damage to CN IV (trochlear) cause?
Diplopia that worsens when looking down
Where are the cell bodies of CN V (Trigeminal) ganglion cells located?
Meckel's cave
What are the three branches of CN V (Trigeminal) and what types of nerves are they?
V1 - Ophthalmic (sensory)

V2 - Maxillary (sensory)

V3 - Mandibular (motor)
Where does the V1 (ophthalmic) branch of CN V (trigeminal) leave the skull?
Superior orbital fissure
Where does the V2 (maxillary) branch of CN V (trigeminal) leave the skull?
Foramen rotundum
Where does the V3 (mandibular) branch of CN V (trigeminal) leave the skull?
Foramen ovale
What does the V1 (ophthalmic) branch of CN V (trigeminal) innervate?
Cornea

Iris

Ciliary body

Lacrimal gland

Nasal cavity

Eyelids

Eyebrows

Forehead
What does the V2 (maxillary) branch of CN V (trigeminal) innervate?
Maxillary teeth

Skin

Mouth

Nasal cavity

Sinuses
What does the V3 (mandibular) branch of CN V (trigeminal) innervate?
Muscles of mastication

Mylohyoid

Anterior belly of digastric

Anterior 2/3 of tongue

Buccal mucosa
From where does CN VI (abducens) originate?
Ventral medial pons
(Near pontine-medullary junction)
What is the path of CN VI (abducens)
Through cavenous sinus

Out superior orbital fissure
What does CN VI (abducens) innervate?
Motor innervation to the lateral rectus muscle of the eye
What does the lateral rectus muscle of the eye do?
Abducts the eye
What can arise with a problem involving CN VI (abducens)?
Horizontal diplopia
What are the branches of CN VII (facial)?
Temporal

Zygomatic

Buccal

Marginal mandibular

Cervical

"To Zanzibar By Motor Car"
Where does CN VII (facial) emerge from the brain?
Ventrolateral brain stem near the pontine-medullary junction
Describe the path of CN VII (facial)
Travels through subarachnoid space and enters internal auditory meatus

Travels through temporal bone with CN VIII

Takes a bend at the geniculate ganglion

Exits the skull through the stylomastoid foramen
What does the temporal branch of CN VII (facial) innervate?
Auricularis superior

Auricularis inferior

Frontal belly of occipitofrontalis

Superior orbicularis oculi
What does the zygomatic branch of CN VII (facial) innervate?
Inferior orbicularis oculi
What does the buccal branch of CN VII (facial) innervate?
Buccinator

Muscles of the upper lip

Orbicularis oris (upper)

Levator labii superioris (inferior fibers)
What does the marginal mandibular branch of CN VII (facial) innervate?
Lower lip and chin
What does the cervical branch of CN VII (facial) innervate?
Platysma
What is the function of CN VIII (vestibulocochlear)?
Special sensory hearing and vestibular sensation
Where does CN VIII (vestibulocochlear) originate?
Brain stem near pontine-medullary junction
Describe the path of CN VIII (vestibulocochlear)
Goes through the internal auditory meatus (with CN VII)

Divides into auditory part and vestibular part (each with ganglia)

Never leaves temporal bone of skull