Exam 3 Nerves Flashcards
GSA
General Somatic Afferent
Somatosensory
Sensation from skin, external ear, oral and nasal cavities
Carried by CN V, VII, IX, X
GSE
General Somatic Efferent
Somatomotor
To skeletal muscle of eye, tongue; SCM and trapzeius mm.
Carried by CN III, IV, VI, XI, XII
GVA
General Visceral Afferent
Viscerosensory
Sensation from pharynx; stretch receptors of the gut,
baroreceptors of the carotid and aortic bodies,
chemoreceptors of gut and carotid body
Carried by CN VII, IX, X
GVE
General Visceral Efferent
Visceromotor
CN only carry parasympathetic innervation to smooth and
cardiac mm., salivary and lacrimal glands, mucus glands
Carried by CN III, VII, IX, X
SSA
Special Somatic Afferent
Vision, hearing, balance (CN II, VIII)
SVA
Special Visceral Afferent
Smell and Taste (CN I, VII, IX, X)
SVE
Special Visceral Efferent
Branchiomotor
To skeletal muscle derived from the branchial arches;
e.g.: mm of mastication, facial expression, pharynx
(swallowing), larynx (speech)
Carried by CN V, VII, IX, X
Autonomic Function Lacrimal gland
SNS: controls blood flow to gland
PSNS: increases tear production
Autonomic Function mucosa
SNS: controls blood flow to mucosa
PSNS: increases mucus production
Autonomic Function salivary gland
SNS: controls blood flow; produces thick, viscous mucus for respiration
PSNS: produces thin, watery mucus for digestion
Horner’s Syndrome
Damage to sympathetic structures in upper thorax or neck Symptoms: • Ptosis (drooping eyelid) • Miosis (pupil constriction) • Anhidrosis (loss of sweating) Symptoms are unilateral.
PSNS CN III
Ganglion: ciliary
target: ciliary body, constrictor pupillae muscles
PSNS CN VII
Ganglion: pterygopalatine and submandibular
target: lacrimal gland and submandibular and sublingual glands respectively
PSNS CN IX
ganglion: otic
target: parotid gland
PSNS CN X
ganglion: intramural (ganglia are in/near ear)
target: viscera of neck, thorax, and abdomen
CN I
Olfactory N. • Special sensory (SVA) • Sensation of olfaction (smell) • Not a true nerve, but a nerve tract (composed of 2° sensory neurons in olfactory bulb) • 1° neurons are receptor cells in epithelial lining of nasal cavity, axons pierce cribriform plate of ethmoid bone • CN I is outgrowth of cerebrum
CN II
Optic N. • Special sensory (SSA) • Again, not a true nerve, but a nerve tract (composed of axons of 2° sensory neurons) • 1° neurons are receptor cells are photoreceptor cells in retina • Outgrowth of diencephalon • Optic nerve: Between chiasm and retina • Optic chiasm: where optic n. fibers from the nasal side of the retina (lateral visual field) cross over to the contralateral side of the brain • Optic tract: between chiasm and thalamus Enters cranial cavity through optic foramen
CN III
Oculomotor N. exits through superior orbital fissure • Motor (GSE, GVE) • Somatomotor (GSE) to 4 extraocular muscles, 1 elevator muscle of the upper eyelid • Visceromotor (GVE) to the ciliary ganglion • Pupillary constriction reflex and lens accommodation reflex Somatomotor Function (GSE) • Superior rectus m. • Medial rectus m. • Inferior rectus m. • Inferior oblique m. • Levator palpebrae superioris m. Visceromotor (GVE) component • Pupillary light reflex • Pupil contraction in response to bright light • Constrictor pupillae m. (CN III) • Accommodation reflex • Changing focus between near and far objects • Ciliary m. (CN III) • Pre-ganglionic fibers carried by CN III from EdingerWestphal nucleus • Synapse in the ciliary ganglion • Post-ganglionics carried by short ciliary nerves to: • Constrictor pupillae mm. • Ciliary body m.
CN IV
Trochlear N. exits through superior orbital fissure • Motor (GSE) • Somatomotor (GSE) • Superior oblique m.
CN V
Trigeminal N. Mixed Sensory-Motor Function (GSA, SVE) Three main branches: • CN V1 , Opthalmic n. (GSA) • CN V2 , Maxillary n. (GSA) • CN V3 , Mandibular n. (GSA, SVE) Somatosensory (GSA) All branches: skin of face, meninges • Cell bodies of GSA neurons found in trigeminal (semilunar) ganglion • Located in middle cranial fossa • Inside cavernous sinus V1: Opthalmic • Conjunctiva of eye • Bridge of nose • Nasal cavity V2: Maxillary • Upper teeth, oral cavity • Nasal mucosa V3: Mandibular • Lower teeth • Tongue Branchiomotor (SVE) • CN V3 (Mandibular n.) • Mm. of mastication: temporalis, masseter, medial and lateral pterygoid mm. • Tensor veli palatini m. • Mylohyoid m. • Anterior belly of digastric m. • Tensor tympani m. CN V1: passes through superior orbital fissure into orbit CN V2: passes through foramen rotundum into pterygopalatine fossa CN V3: passes through foramen ovale into infratemporal fossa
CN VI
Abducens N. • Motor (GSE) • Somatomotor (GSE) • Lateral rectus m. exits through superior orbital fissure
CN VII
Visceromotor (GVE): Parasympathetic function: • Lacrimation (tear production) • Mucous production in nasal cavity, paranasal sinuses • Salivation from submandibular and sublingual glands Branchiomotor (SVE): • Mm. of facial expression • Stapedius m. • Posterior belly of digastric m. • Stylohyoid m. Pass through stylomastoid f. Somatosensory (GSA): • External ear (pinna) Viscerosensory (GVA): • Sensation from the mucosal lining of the nasopharynx and soft palate • Follows the same path as SVA fibers. Special sensory (SVA): • Taste to anterior 2/3 of tongue • Synapse in geniculate ganglion • Chorda tympani n. • Exits facial canal through petrotympanic fissure • Travels with lingual nerve (CN V3) to tongue
CN VIII
Vestibulocochlear N. • Sensory (SSA) • Sensations of hearing (from cochlea) and balance (from vestibular apparatus) exits through internal acoustic meatus
CN IX
Glossopharyngeal N. Mixed Sensory-Motor Function: • Visceromotor (GVE) • Branchiomotor (SVE) • Somatosensory (GSA) • Viscerosensory (GVA) • Special sensory (SVA) Glossopharyngeal ganglia: contain cell bodies for 1° sensory neurons • Superior (jugular) ganglion of IX: somatosensory (GSA) neurons from posterior tongue • Inferior (petrous) ganglion of IX: viscerosensory (GVA) neurons from middle ear, pharynx; taste (SVA) neurons from posterior tongue Tympanic nerve (of Jacobson) re-enters middle ear through inferior tympanic canaliculus • Sensory (GVA) to middle ear and internal surface of tympanic membrane • Lesser petrosal nerve (GVE) to otic ganglion and parotid gland Visceromotor (GVE) • Parotid gland Parasympathetic, stimulates saliva production Otic Ganglion • CN IX carries pre-ganglionic fibers from inferior salivatory nucleus in medulla. – Lesser petrosal nerve branches from tympanic plexus in middle ear. – Re-enters cranial cavity through lesser petrosal hiatus. – Travels with CN V3 through foramen ovale • Synapse in otic ganglion in infratemporal fossa – Post-ganglionic fibers travel with auriculotemporal nerve (CN V3) to parotid gland Branchiomotor (SVE) • Stylopharyngeus m. • This is the only place you will see CN IX in gross anatomy lab • Look for stylopharyngeus inserting between the superior and inferior pharyngeal constrictor muscles (innervated by CN X) Somatosensory (GSA) • Posterior 1/3 of tongue Special Sensory (SVA) • Taste from posterior 1/3 of tongue and circumvallate papillae Viscerosensory (GVA) • Carotid sinus (baroreceptors) • Carotid body (chemoreceptors) • Upper pharynx (via pharyngeal plexus) • Oro- & naso-pharynx • Middle ear
CN X
Mixed Sensory-Motor Function: • Visceromotor (GVE) • Branchiomotor (SVE) • Somatosensory (GSA) • Viscerosensory (GVA) • Special sensory (SVA) Visceromotor (GVE) • Mucous membranes • Pharynx • Larynx • Trachea • Thoracic organs • Heart: slows heart rate, decreases cardiac output • Lungs: decreases respiratory rate • Abdominal organs • Foregut & midgut: stimulates peristalsis Branchiomotor (SVE) • Soft palate mm. • Levator veli palatini m. • Palatopharyngeus m. • Palatoglossus m. • Salpingopharyngeus m. • Pharyngeal constrictors (via pharyngeal plexus) • Intrinsic laryngeal muscles (via recurrent laryngeal nerve) • Cricothyroid m. (via external branch of superior laryngeal n.) Somatosensory (GSA) • External ear and canal • Tympanic membrane (external aspect) Viscerosensory (GVA) • Inferior pharynx • Laryngopharynx • Larynx • Thoracic organs • Heart & lungs • Aortic body • Abdominal organs • Foregut & midgut Special Sensory (SVA) Sense of taste • Root of tongue • Epiglottis Vagal ganglia: contain cell bodies for 1° sensory neurons • Superior (jugular) ganglion of X: somatosensory (GSA) neurons from external ear • Inferior (nodose) ganglion of X: viscerosensory (GVA) neurons from GI tract; taste (SVA) neurons from epiglottis Note these ganglia are sometimes fused together
CN XI
Accessory N. Motor function: • Somatomotor (GSE) • Trapezius m. • Sternocleidomastoid m. CN XI arises from upper cervical spinal cord, enters cranial cavity through foramen magnum, exits through jugular foramen.
CN XII
Hypoglossal N. Motor function: • Somatomotor (GSE) • Extrinsic tongue mm. • Genioglossus m. • Hyoglossus m. • Styloglossus m. • Intrinsic tongue mm. Exit from cranial cavity via hypoglossal canal.
Pupillary Diameter
Constriction: • Normal: caused by parasympathetics • Abnormal (sympathetic lesion)= miosis Dilation: • Normal: caused by sympathetics • Abnormal (parasympathetic lesion) = mydriasis
Oculomotor Palsy
Motor + parasympathetic nerve damage
Ptosis + Mydriasis (dilated pupil)
Loss of levator palpebrae superioris m. (skeletal m.)
Unopposed dilator pupillae m.
Trigeminal Neuralgia (TNA, “typical TN”)
• Neuropathic pain in one side of the face
• May be in one or more trigeminal regions
• TNA caused by vascular compression of the trigeminal ganglion inside the
cranial cavity
• Compression-induced myelin loss causes pain
Characterized by episodes of brief, intense facial pain over one of the three areas of CN V distribution
Pain is so intense that patient winces, which produces a facial muscle tic
Etiology: uncertain
Usually affects Maxillary (V2) or Mandibular (V3) nerve unilaterally
Usually in those older than 50
Triggers: touch or draft of cool air
Characterized by episodes of brief, intense facial pain over one of the three areas of CN V distribution
Trigeminal Neuropathy (TNO, “atypical TN”)
- Peripheral damage due to trauma, usually to a single branch of CN V
- Myelin loss causes pain
- Axonal damage causes loss of sensation and/or motor function
Facial Canal
CN VII exits the cranial cavity through the internal acoustic meatus. Facial canal: between the IAM and the stylomastoid foramen. Geniculate ganglion: contains cell bodies for sensory neurons (1° GSA/GVA/SVA) in CN VII
Pterygopalatine Ganglion
CN VII (facial nerve) carries pre-ganglionic fibers from
superior salivatory nucleus in pons.
– In facial canal, PN fibers branch off as greater petrosal nerve.
– Greater petrosal nerve merges with the deep petrosal nerve
(SN fibers from carotid plexus) to form the nerve of the
pterygoid canal (AKA Vidian n.)
• Synapse in pterygopalatine ganglion (in fossa)
– Postganglionic fibers to lacrimal gland travel with CN V2
(zygomatic n.) and CN V1 (lacrimal n.) into/through orbit.
– Postganglionic fibers to nasal mucosa travel with CN V2
(pharyngeal, palatine, nasal nn.) to nasal, palatine, and
pharyngeal mucosa
Submandibular Ganglion
CN VII carries pre-ganglionic fibers from
superior salivatory nucleus in pons.
• Chorda tympani branches off CN VII in facial
canal, travels with lingual nerve (CN V3)
• Synapse in submandibular ganglion
• Short post-ganglionic fibers travel to
submandibular and sublingual glands
Auditory neuromas
(tumors of internal acoustic meatus) • Hearing and balance impairment (CN VIII, all others by CN VII) • Loss of lacrimation (tear production) • Loss of taste from anterior tongue • Dryness of nasal and sinus mucosa • Xerostomia (dry mouth) • Paralysis of muscles of facial expression
Bell’s Palsy
(idiopathic facial palsy)
• Unilateral paralysis of muscles of facial expression
• Cause: compression in stylomastoid foramen
Location of lesion and structures affected:
- Near origin from pons or geniculate ganglion – loss of motor, gustatory (taste) and autonomic functions (secretions)
- Distal to geniculate ganglion, but proximal to origin or chorda tympani n. – same dysfunctions, but lacrimation is not affected
- Near stylomastoid foramen or Parotid gland – loss of motor function only
Frey’s Syndrome
Gustatory Sweating
Localized hyperhidrosis (sweating) and erythema
(redness)
• In response to gustatory stimuli: eating, smelling
food, thinking about food
• Often occurs with surgical damage to
auriculotemporal n. (sensory branch of CN V3
traveling with PN from CN IX)
• PN stimulation of parotid gland for saliva production
also (improperly) stimulates eccrine sweat glands
(normally innervated by SN)
Cranial Foramina
Cranial Nerve Exits cranial cavity through: CN I (olfactory n.) Cribriform plate CN II (optic n.) Optic foramen CN III (oculomotor n.) Superior orbital fissure CN IV (trochlear n.) Superior orbital fissure CN V1 (opthlamic n.) Superior orbital fissure CN V2 (maxillary n.) Foramen rotundum CN V3 (mandibular n.) Foramen ovale CN VI (abducens n.) Superior orbital fissure CN VII (facial n.) Internal acoustic meatus CN VIII (vestibulocochlear n.) Internal acoustic meatus CN IX (glossopharyngeal n.) Jugular foramen CN X (vagus n.) Jugular foramen CN XI (accessory n.) Jugular foramen CN XII (hypoglossal n.) Hypoglossal canal
Cranial Foramina Trigeminal Nerve (CN V)
Supraorbital nerve (CN V1) Supraorbital foramen/notch
Infraorbital nerve (CN V2) Infraorbital foramen
Nasopalatine nerve (CN V2) Sphenopalatine foramen
Zygomatic nerve (CN V2) Inferior orbital fissure
Inferior alveolar nerve (CN V3) Mandibular foramen
Mental nerve (CN V3) Mental foramen
Middle meningeal nerve (CN V3) Foramen spinosum
Cranial Foramina Facial Nerve (CN VII)
Chorda tympani Petrotympanic fissure Greater petrosal nerve Greater petrosal hiatus, pterygoid canal Temporal branch Stylomastoid foramen Zygomatic branch Stylomastoid foramen Buccal branch Stylomastoid foramen Mandibular branch Stylomastoid foramen Cervical branch Stylomastoid foramen
Cranial Foramina Glossopharyngeal Nerve (CN IX)
Lesser petrosal nerve Lesser petrosal hiatus, foramen ovale
Clinical Tests for Lower Cranial Nerves: Gag reflex
- Sensory: CN IX
- Motor: CN X
- Structure: pharyngeal plexus
Clinical Tests for Lower Cranial Nerves: Phonation (speech)
- Motor: CN X
* Structure(s): larynx
Clinical Tests for Lower Cranial Nerves: Shrug Test
- Elevate shoulders against resistance
- Motor: CN XI
- Structure: trapexius
Clinical Tests for Lower Cranial Nerves: Head Turn
Turn head against resistance
• Motor: CN XI
• Structure: sternocleidomastoid
Clinical Tests for Lower Cranial Nerves: Tongue protrusion
• Motor: CN XII • Tongue deviates towards side of lesion • Unopposed genioglossus m. (protracts tongue)
Clinical Tests for Lower Cranial Nerves: Soft palate – uvula position
• Motor: CN X • Uvula deviates away from side of lesion • Unopposed levator veli palatini m. (elevates uvula)
