Laboratory Identifications: A Study Guide for the Cranial Nerve Handout with the Skull in Hand

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Olfactory Nerve (CN1)

• Functional component(s)
• Cribriform plate of the ethmoid bone
  • Anterior cranial fossa to nasal cavity
• Crista galea
  • Falx cerebri
• Foramen cecum
  • Anterior cranial fossa to nasal cavity, superior sagittal sinus
• Ethmoidal air cells
  • Anterior ethmoidal nerve
• Frontal air sinus

Optic Nerve (CN2)

• Functional component(s)
• Optic canal
• Lesser wing of the sphenoid bone
• Chiasmatic groove
• Anterior lip of chiasmatic groove
  • Boundary between and anterior and middle cranial fossa
• Anterior clinoid process
  • Diaphragma sellae
  • Internal carotid artery
• Sella turcica
  • Tuberculum sellae
  • Hypophyseal fossa
  • Dorsum sellae
• Ophthalmic artery
• Central artery of the retina
• Nasocillary nerve
• Annulus tendineus

Oculomotor Nerve (CN3)

• Functional component(s)
• Superior orbital fissure
• Lesser wing of the sphenoid bone
• Greater wing of the sphenoid bone
• Cavernous sinus
• Carotid siphon
• Superior division
• Inferior division
• Ciliary ganglion
• Annulus tendineus

Trochlear Nerve (CN4)

• Functional component(s)
• Superior orbital fissure
• Cavernous sinus
• Annulus tendineus
• Ethmoidal air cells

Trigeminal Nerve (CN5) - Ophthalmic Division

• Functional component(s)
• Superior orbital fissure
• Annulus tendineus
• Lacrimal nerve - functional component proximal and distal, distribution
  • Parasympathetic communicating branch
• Frontal nerve - medial and lateral branches,
  • Supraorbital nerve, distribution
  • Supratrochlear nerve, distribution
• Supratrochlear nerve - relationship the the trochlea, distribution
• Nasociliary nerve - relationship to optic nerve, distribution
  • Sensory root of ciliary ganglion, elaborates branches of short ciliary nerves
  • Long ciliary nerves - GSA cornea
  • Short ciliary nerves - Native and non-native functional components, distribution
  • Posterior ethmoidal nerve - distribution to posterior ethmoidal air cells and sphenoid sinus
  • Anterior ethmoidal nerve - distribution and pathways leading to the bridge of the nose
  • Infratrochlear nerve - relationship to the trochlea, distribution
• Anterior and posterior ethmoidal foramina

Trigeminal Nerve (CN5) - Maxillary Division

• Functional component(s)
• Foramen Rotundum - middle cranial fossa to pterygopalatine fossa
  • Transmits maxillary nerve
• Pterygoid Canal - middle cranial fossa to pterygopalatine fossa
  • Transmits the nerve of the pterygoid canal (Vidian nerve)
  • Anterior lip of the lacerate foramen
  • Carotid groove
  • Sphenoid air sinus
• Nerve of the pterygoid canal - functional components and parent nerves, distribution
  • Hiatus of the canal for the greater superficial petrosal nerve
  • Groove for the greater superficial petrosal nerve (VII)
  • Intracranial opening of the carotid canal at the lacerate foramen
  • Internal carotid plexus
  • Deep petrosal nerve
  • Apex of the petrous portion of the temporal bone
• Pharyngeal Canal - pterygopalatine fossa to nasopharynx
  • Transmits pharyngeal nerve to nasopharynx, native and non-native functional components, distribution
  • Ala of the vomer
  • Vaginal process of medial pterygoid plate
  • Perpendicular plate of the palatine bone
  • Palatovaginal canal (pharyngeal canal)
• Lesser palatine canal - pterygopalatine fossa to oral cavity
  • Transmits lesser palatine nerve to soft palate, native and non-native functional components, distribution
  • Medial pterygoid plate
  • Hamulus - tensor veli palatini
  • Perpendicular plate of the palatine bone
• Greater palatine canal - pterygopalatine fossa to oral cavity
  • Transmits greater palatine nerve to hard palate, native and non-native functional components, distribution
  • Sphenopalatine foramen - why so named?
• Sphenopalatine foramen - pterygopalatine fossa to nasal cavity
  • Transmits lateral posterior nasal nerves and nasopalatine nerve to nasal cavity, native and non-native functional components, distribution
  • Superior, middle, and inferior nasal chonchae (turbinates when covered with erectile tissue)
  • Superior, middle, and inferior nasal meatae and associated drainages
  • Perpendicular plate of the ethmoid bone
  • Vomer
  • Uncinate process, ethmoidal bulla, infundibulum, and hiatus semilunaris
  • Sphenoethmoidal recess - drainage of sphenoid sinus, posterior air cells
• Inferior orbital fissure - pterygopalatine fossa to orbit
  • Greater wing of the sphenoid bone and the maxilla
  • Transmits maxillary nerve and zygomatic nerve to the orbit
  • Infraorbital nerve - native and non-native functional components, distribution
  • Zygomatic nerve - native and non-native functional components
  • Zygomaticofacial nerve - native and non-native functional components, distribution
  • Zygomaticotemporal nerve - native and non-native functional components, distribution
  • Canals for the zygomaticotemporal and zygomaticofacial nerves
  • Lacrimal nerve (from ophthalmic division of trigeminal) - native and non-native functional components, distribution
  • Infraorbital groove, infraorbital canal, and infraorbital foramen
  • Middle superior alveolar nerve, native and non-native functional components, distribution
  • Anterior superior alveolar nerve, native and non-native functional components, distribution
• Pterygomaxillary fissure - pterygopalatine fossa to infratemporal fossa
  • Anterior border of the lateral pterygoid plate and posterior border of maxilla
  • Transmits posterior superior alveolar nerve, native and non-native functional components, distribution
  • Transmits terminal branches of maxillary artery

Trigeminal Nerve (CN5) - Mandibular Division

• Functional component(s)
• Foramen ovale - transmits mandibular nerve from middle cranial fossa to infratemporal fossa
• Auriculotemporal nerve
  • Functional components - native and non-native
  • Otic ganglion
  • Postganglionic parasympathetic and sympathetic non-native components
  • Foramen spinosum and middle meningeal artery
  • Splits around middle meningeal artery
  • Posterior to mandibular fossa
  • Anterior to external auditory meatus
  • Infratemporal fossa to parotid region to temporal fossa
  • Communicating branch
  • Stylomastoid foramen and facial nerve
• Deep temporal nerves
  • Functional components
  • Infratemporal crest
  • Zygomatic arch
  • Temporal fossa
• Inferior alveolar nerve
  • Functional components
  • Lingula
    • Sphenomandibular ligament
  • Mandibular foramen
  • Inferior alveolar processes
  • Mental foramen
    • Mental nerve - distribution
  • Tensor tympani nerve - functional component and function
    • Bony auditory tube
    • Tegmen tympani
  • Masseteric nerve
    • Functional component
    • Mandibular notch
  • Nerve to mylohyoid
    • Mylohyoid groove
    • Mylohyoid muscle - origin and insertion
    • Mylohyoid line
    • Anterior and posterior belly of digastric - origin and insertion
    • Digastric fossa
    • Digastric groove
  • Tensor veli palatini - origin and insertion
    • Scaphoid fossa
    • Hamulus of medial pterygoid plate
    • Midline raphe
• Lingual nerve
  • Functional components - native and non-native
  • Lateral pterygoid muscle - origin and insertions
  • Medial pterygoid muscle - origin and insertion
  • Pterygomandibular raphe
    • Superior constrictor
    • Buccinator
  • Chorda tympani
    • Petrotympanic fissure
  • Occlusion plane
• Buccal nerve
  • Functional component
  • Pterygomandibular raphe
  • Masseter - origin and insertion

Abducens Nerve (CN6)

• Functional component(s)
• Annulus tendineus
• Superior orbital fissure transmits abducens from the middle cranial fossa to the orbit
• Cavernous sinus - vulnerable to injury by infection
• Lateral rectus
  • Two heads of origin span greater and lesser wings of sphenoid bone, transmit abducens nerve
  • Ciliary ganglion
  • abducens nerve on internal surface
  • Lacrimal nerve external and superior

Facial Nerve (CN7)

• Functional component(s)
• Internal auditory meatus
  • Transmits facial nerve from posterior cranial fossa into the petrous temporal bone and proximal facial canal
• Genu of the facial canal - Wait for temporal bone demonstration
  • Geniculate ganglion
  • Greater superficial petrosal nerve - functional components
• Hiatus of the canal for the greater superficial petrosal nerve
  • Transmits greater superficial nerve from the facial canal to the middle cranial fossa
• Groove for the greater superficial petrosal nerve
  • Guides the greater superficial petrosal nerve toward the lacerate foramen
  • Opening of the carotid canal into the middle cranial fossa
  • Apex of the petrous portion of the temporal bone
  • Clivus
  • Superior petrosal sinus
  • Inferior petrosal sinus
  • Basilar venous plexus
  • Emissary vein between cavernous sinus and pterygoid venous plexus
  • Trigeminal cave
  • Trigeminal ganglion
  • Dorsum sellae
  • Internal carotid plexus
  • Deep petrosal nerve
  • Posterior boundary of the cavernous sinus
  • Carotid siphon
  • Posterior opening of the pterygoid canal into the region of the lacerate foramen at the anterior lip of the lacerate foramen
• Stapedial nerve in the middle ear - wait for temporal bone dissection demonstration
• Petrotympanic fissure
  • Transmits chorda tympani nerve from the middle ear to the infratemporal fossa
  • Functional components of chorda tympani - joins lingual nerve within infratemporal fossa
  • Petrous part of temporal bone
  • Tympanic cavity
  • Mandibular fossa
  • Mandibular condyle - appreciate relationship of the petrotympanic fissure to the temporomandibular joint
  • Inferior alveolar processes - appreciate relationship of lingual nerve to the submandibular duct
• Stylomastoid foramen
  • Transmits the facial nerve from the distal facial canal to the parotid region
  • Digastric groove - posterior belly digastric muscle
  • Styloid process - stylohyoid (CN7), styloglossus (CN12), and stylopharyngeus muscles (CN9)

Vestibulocochlear Nerve (CN8)

• Functional component(s)
• Internal auditory meatus
  • Transmits vestibulocochlear nerve from posterior cranial fossa into the petrous temporal bone
• Superior, middle, and inferior semicircular canals (wait for temporal bone demonstration)
• Bony labyrinth
• Spiral ganglion
• Vestibular ganglion
• Mastoid air cells - Wait for temporal bone demonstration
  • Sigmoid sinus
  • Aditus
  • Middle ear
  • Auditory tube
  • Nasopharynx
• Ossicles of the middle ear - Wait for temporal bone demonstration
  • Tympanic membrane
  • Chorda tympani nerve
  • Oval window
  • Round window
  • Malleus
  • Incus
  • Stapes

Glossopharyngeal Nerve (CN9)

• Functional component(s)
• Jugular foramen
• Tympanic canaliculus
  • Recurrent tympanic nerve
• Tegmen tympani
  • Tympanic plexus - functional components
• Hiatus of the canal for the lesser superficial petrosal nerve
  • Lesser superficial petrosal nerve - functional components
• Groove for the lesser superficial nerve
  • Observe the groove heading toward either foramen ovale or toward foramen spinosum
• Foramen ovale (or spinosum)
  • Transmits lesser superficial nerve from the tympanic cavity to the infratemporal fossa

Vagus Nerve (CN10)

• Functional component(s)
• Jugular foramen
  • Transmits vagus nerve from posterior cranial fossa to the base of the skull
• Mastoid canaliculus
  • Transmits GSA of auricular branch of vagus
    • Jugular ganglion (superior vagal ganglion) supports GSA cell bodies

Accessory Nerve (CN11)

• Functional component(s)
  • For our purposes we are treating trapezius and sternocleidomastoid as SVE innervated despite the writings of some authors who suggest otherwise.
• Jugular foramen
  • Transmits the accessory nerve from posterior cranial fossa to the base of the skull

Hypoglossal Nerve (CN12)

• Functional component(s)
• Hypoglossal Canal
  • Transmits hypoglossal nerve from posterior cranial fossa to the base of the skull
  • Transverse to occipital condyle
• Condylar canal - emissary vein
  • Longitudinal to occipital condyle