Cranial Nerves/Boundaries of Structures

What part of the skull does CN I (Olfactory) come out of?

Cribiform plate in ethmoid bone

What lobe is the primary olfactory cortex located in?

Entorhinal cortex or temporal lobe

What would a lesion of CN I (Olfactory) cause?

Anosmia

What are the nucleus cells for the optic tract?

Ganglion cells of the retina

What is the pathway of CN II (Optic)

Optic nerve, optic chiasma, optic tract, lateral geniculate body, superior brachium, superior colliculus, optic radiation, cuneus and lingual gyri

What lobe is the primary visual cortex located in?

Cuneus and Lingual gyri of the occipital lobe

Where in the body does light reflex information go to?

Superior colliculus via the superior brachium

How does the lateral geniculate nucleus fibers reach the primary visual cortex?

Optic radiation to contralateral cortex

Where does CN II exit the skull?

Optic canal

What would a lesion of CN II cause?

Anopsia

What are the nuclei of CN III (Oculomotor)

Oculomotor nucleus (motor) and Edinger-Westphalia nucleus (parasympathetic)

Which nucleus is responsible for the motor to the extraocular muscles

Oculomotor nucleus

What nucleus is responsible for the pupillary constriction and accommodation?

Edinger-Westphal nucleus

What muscles are innervated by the Oculomotor nerve?

Superior recuts, medial recuts, inferior recuts, inferior oblique, and lavatory palpebrae superioris

What is the function of the sphincter pupillae muscle?

Pupillary constriction in response to light and accommodation for near vision

What is the function of the ciliaris muscle?

Thickening of the lens during accommodation

What nucleus does the ocuolomotor parasympathetic fibers synapse with?

Ciliary ganglion

What two muscles does true short ciliary nerves supply?

Ciliaris and Sphincter pupillae

Where does the postganglionic sympathetic fibers originate from?

Internal carotid plexus (from cervical sympathetic ganglion)

What is ptosis?

drooping eyelid

What is lateral strabismus?

Eye deviates laterally because medial rectus is paralyzed and lateral rectus is unopposed

What is mydriasis?

Enlarged, unreactive pupil to light (when sphincter pupillae doesn't work)

What is cycloplegia?

Accomadation does not occur due to the sphincter pupillae and ciliaris muscles not functioning

What symptoms are found when the Oculomotor Nerve gets lesioned?

Diplopia, ptosis, lateral strabismus, mydriasis, and cycloplegia

Where in the skull goes the Oculomotor Nerve exit?

Superior orbital fissure

What is the light reflex test?

-Shining of a light in the eye to see if the pupil constricts (tests the sphincter pupillae)

-Used to test the Oculomotor nerve (CN III)

What is the accommodation reflex test?

-Test that involves having the patient stare far away and then look at something close; the pupil should constrict when this occurs

-Tests the sphincter pupillae and ciliaris muscles when tests the CN III

Where does the dilator pupillae come from?

Internal carotid plexus coming off the superior cervical ganglion

What is the nucleus of the Trochlear Nerve (CN IV)?

Trochlear nucleus

At what level does the trochlear nerve exit?

Midbrain at the level of the inferior colliculus in the anterior portion of the periaqueductal gray

Where does the Trochlear nerve leave the brain stem?

Decussates in the superior medullary velum and exits inferior to the inferior colliculi

What is the function of the Trochlear Nerve (CN IV)?

Extraocular movements (superior oblique muscle)

What symptoms would occur if the Trochlear nerve was lesioned?

Diplopia when looking down and in and head tilt to the opposite side (Trochlear palsy)

Where in the skull does the Trochlear Nerve exit?

Superior orbital fissure

What is the nucleus of the Abducens Nerve (CN VI)?

Abudcent nucleus

At what level does the abducent nerve exit?

Lower pons at the level of the facial colliculus

Where does the abducens nerve leave the brain stem?

Pontomedullary junction between the basilar pons and pyramids

What is the function of the Abducens Nerve (CN VI)?

Extraocular movements (lateral recuts muscle)

What symptoms would occur if the Abducens Nerve was lesioned?

Medial strabismus and Diplopia

Where in the skull does the Abducens Nerve exit?

Superior orbital fissure

What are the nuclei of the Trigeminal Nerve (CN V)?

1. Nucleus of the spinal tract of trigeminal (pain and temperature)

2. Chief sensory nucleus (touch)

3. Mesencephalic nucleus (proprioception)

4. Motor nucleus (muscles of mastication)

What nucleus is responsible for the pain and temperature of the face?

Nucleus of the spinal tract of trigeminal

What nucleus is responsible for the touch sensation of the face?

Chief sensory nucleus

What nucleus is responsible for the proprioception to the face?

Mesencephalic nucleus

What nucleus is responsible for the muscles of mastication?

Motor nucleus

Where does the Ophthalmic peripheral branch of the Trigeminal (V1) exit the skull?W

Superior orbital fissure

Where does the Maxillary peripheral branch of the Trigeminal (V2) exit the skull?

Foramen rotundum and enters the pterygopalatine fossa

What part of the skull does the Maxillary Nerve completely leave?

Infraorbital foramen

Where does the Mandibular peripheral branch of the Trigeminal (V3) exit the skull?

Foramen ovale

The middle meningeal artery re-enters the skull where?

Foramen spinosum

What are the functions of the Trigeminal Nerve (CN V)?

-Sensory to the face, scalp, teeth, most of the tongue, oral and nasal mucosa, dura mater, and cerebral blood vessels

-Motor to the muscles of the mastication (masseter, temporal is, medial and lateral pterygoid muscles), tensor tympani and tensor veli palatini muscles

What is the function of the medial pterygoid muscle?

Closes the mouth

What is the function of the lateral pterygoid muscle?

Opens the mouth

What is the function of the tensor tympani and tensor veli palatini muscles?

Closes the nasal cavity off when opening the mouth

What symptoms occur when the Trigeminal nerve is lesioned?

Trigeminal neuralgia, facial anesthesia, and the inability/difficulty to bite down

What are the nuclei associated with the Vestibulocochlear Nerve (CN VIII)?

Vestibular nuclei and cochlear nuclei

Where does the Vestibulocochlear nerve exit the brain stem?

Cerebellopontine angle (below CN VII and above the flocculus)

What is the function of the Vestibulocochlear Nerve (CN VIII)?

Balance and equilibrium and hearing

What are some of the examination tests for CN VIII?

Caloric test and barony chair test

What symptoms occur when the Vestibulocochlear nerve is lesioned?

Vertigo, nystagmus, dysequilibrium

Where in the skull does the Vestibulocochlear Nerve exit?

Internal acoustic meatus

What are the nuclei of the Vagus Nerve (CN X)?

1. Dorsal motor nucleus (parasympathetic)

2. Nucleus ambiguus (motor)

3. Nucleus of solitary tract (taste and parasympathetic)

4. Nucleus of the spinal tract of trigeminal (sensory)

What are the functions of the Vagus Nerve (CN X)

-Parasympathetics to the thorax and abdomen

-Motor to pharyngeal constrictors, intrinsic laryngeal muscles, palatine muscles, and upper esophagus

-Taste fibers from the larynx and epiglottis

-Sensory to the pharynx, larynx, the concha of the external ear, and the meninges of the posterior fossa

What symptoms occur when the Vagus Nerve is lesioned?

Hoarseness, dysphagia, loss of gag reflex, and uvulae deviation to the strong side

Where in the skull does the Vagus Nerve exit?

Jugular Foramen

What nuclei are associated with the Accessory Nerve (CN XI)?

Nucleus ambiguus and disperse cell bodies

What are the functions of the Accessory Nerve (CN XI)?

-Cranial accessory: joins the vagus nerve to supply the muscles of the pharynx, larynx, and soft palate

-Spinal accessory: motor to the SCM and trapezius muscles

What symptoms occur if the Accessory Nerve is lesioned?

Inability to rotate head and shrug shoulders

Where in the skull does the Accessory Nerve exit?

Jugular Foramen

What is the nuclei associated with the Hypoglossal Nerve (CN XII)?

Hypoglossal nucleus (under hypoglossal trigone)

What nuclei is responsible for the motor control of the tongue muscles?

Hypoglossal nucleus

What is the function of the Hypoglossal Nerve (CN XII)?

Motor to all of the tongue muscles (except the palatoglossus muscle)

What symptoms occur if the Hypoglossal Nerve is lesioned?

Ipsilateral tongue paralysis and atrophy

Where in the skull does the Hypoglossal nerve exit?

Hypoglossal canal

What are the nuclei associated with the Facial Nerve (CN VII)?

Facial nucleus, Nucleus of the solitary tract, and the superior salivartory nucleus

What nuclei is responsible for the taste and parasympathetics of the face?

Nucleus of the solitary tract

What nuclei is responsible fore the parasympathetics to the lacrimal gland, submandibular gland, and the sublingual gland?

Superior salivatory nucleus

What nuclei is responsible for the motor control of the facial muscles?

Facial nucleus

What are the functions of the Facial Nerve (CN VII)?

-Motor to the muscles of facial expression

-Taste from the anterior 2/3 of the tongue

-Parasympathetic to the lacrimal gland

-Parasympathetic to the submandibular and sublingual salivary glands

What is the peripheral branch of the Facial nerve that supplies motor fibers to the muscles of facial expression?

Motor branch (divided into temporal, zygomatic, buccal, marginal mandibular, and cervical)

What is the preganlionic parasympathetic branch of the Facial Nerve?

Nervous intermedius

Where does nervous intermedius pass to become the greater petrosal nerve?

Internal acoustic meatus

Where in the skull does the Vidian nerve travel through?

Pterygoid canal

What nucleus does the Vidian Nerve synapse with?

Pteryopalatine ganglion

What branch of the pteryopalatine ganglion sends postganglionic fibers to?

Maxillary nerve (V2)

What branch of the maxillary nerve sends postganglionic fibers to?

Zygomaticotemporal nerve (V2)

What branch of the zygomaticotemporal nerve sends postganglionic fibers to?

Lacrimal nerve (V1)

What does the lacrimal nerve innervate?

Lacrimal glands

What is the peripheral branch of CN VII that supplies parasympathetic to the lacrimal gland?

Greater pterosal nerve

What is the nerve called when the greater petrosla nerve and the deep petrosal nerve combine?

Vidian nerve

Where does the deep petrosal nerve originate?

Off the superior cervical ganglion of the carotid plexus

What is the peripheral branch of CN VII that supplies the parasympathetic to the submandibular and sublingual salivary glands?

Chorda tympani

What nucleus does the chorda tympani synapse with?

Submandibular ganglion

What part of the skull does the chorda tympani travel through?

Petrotympanic fissure

What nerve does the chorda tympani join with to supply the submandibular ganglion?

Lingual nerve (V3)

What is the peripheral branch of CN VII that supplies the taste from the anterior 2/3 of the tongue?

Chorda tympani

What nucleus does the taste branch of the facial nerve end?

Solitary nucleus

What symptoms occur if the Facial Nerve get lesioned?

Bell's palsy

Where in the skull does the Facial Nerve enter?

Internal acoustic meatus

What is the function of the corticobulbar tract?

Innervates the motor nuclei of the cranial nerves on the contralateral side (expect CN VII)