Cranial Nerves.pdf

Cranial Nerves  Cranial Nerves On Old Olympus’s Towering Tops A Finn And German Viewed Some Hops Some Say Marry Money, But My Brother Says Big Brains Matter Most Cranial Nerves Please use Blumenfeld table: 12.2 for Classifications of CN functions Motor...

Cranial Nerves  Cranial Nerves On Old Olympus’s Towering Tops A Finn And German Viewed Some Hops Some Say Marry Money, But My Brother Says Big Brains Matter Most Cranial Nerves Please use Blumenfeld table: 12.2 for Classifications of CN functions Motor Sensory General somatic efferent (GSE) Special visceral afferent (SVA) E.g. to muscle controlling eye movements e.g taste Specialize visceral efferent (SVE) E.g. to muscle controlling mastication General visceral afferent(GVA) sensation from visceral structures General visceral efferent (GVE) E.g to muscle controlling pupil General somatic afferents (GSA) sensation from the face Special somatic afferents (SSA) Smell, vision, vestibular sensations. Identify the Nuclei for each CN Identify nerve exit point from brainstem CN I (Olfactory) Sensory Fibers Function – Smell Specialized somatic afferent (SSA) Cranial Exit – Foramina in cribriform plate of ethmoid bone Processed Olfactory cortex CN II (Optic) Sensory Fibers Function - Sensory Vision from retina (SSA) Cranial Exit – Optic Canal Processed in the superior colliculus and Visual Cortex CN III (Oculomotor) Function Motor to superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris muscles (GSE) Raises superior eyelid Turns eyeball superiorly, inferiorly, and medially Parasympathetic to sphincter pupillae and ciliary muscle (GVE) Constricts pupil and accommodates lens of eye Nuclei: Oculomotor nuclei and parasympathic nuclei of oculomotor (Edinger-Westphal Nuclei)  CN III: Oculomotor Nuclei and Nerve Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.2 CN IV (Trochlear) Function – Motor to superior oblique to assist in turning eye inferolaterally (or inferiorly when adducted) (GSE) Nuclei: Trochlear nuclei lower midbrain Exits midbrain posteriorly- wraps around anteriorly. Cranial Exit – Superior Orbital Fissure  CN V: Trigeminal Nerve (3 Divisions) V1 (Ophthalmic) – Sensory V2 (Maxillary) – Sensory V3 (Mandibular) – Motor  Trigeminal Nerve Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.2 Trigeminal nuclei and nerve root Pons Look at slide 69 for spinal and mesencephalic nuclei  CN VI – Abducens Motor Fibers GSA Function – Motor to lateral rectus muscle to turn eye laterally Nuclei: Abducens nuclei Lower pons Nerve exits brainstem medially at pontomedullary junction. Cranial Exit – Superior Orbital Fissure CN VII (Facial) Exits lateral pontomedullary junction Motor Fibers Function Parasympathetic to submandibular and sublingual salivary glands, lacrimal gland, and glands to nose and palate. Motor to muscles of facial expression and scalp, also stapedius of middle ear, stylohyoid, posterior belly of digastric (SVE) Facial nuclei in lower pons Sensory Fibers Function – Sensation from skin of external acoustic meatus Taste from anterior two thirds of tongue and palate From Trigeminal nuclei (GSA) in upper pons Cranial Exit – Internal acoustic meatus; facial canal; stylomastoid foramen  CN VII: Facial Nerve Innervates muscles of facial expression Sensory innervation of face Taste Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.2 CN VIII (Vestibulocochlear) Sensory (SSA) Function – Vestibular sensation from semicircular ducts, utricle and saccule related to position and movement of head; hearing from spiral organ Vestibular nuclei: upper medulla/lower pons Exits laterally pontomedullary junction Cranial Exit – Internal acoustic meatus CN IX (Glossopharyngeal) SVE – Parasympathetic to parotid gland GVE – Motor to stylopharygeus to assist swallowing GSA – Sensation of ear, pharynx, middle ear GVA – Sensation of carotid body and sinus SVA – Taste from posterior 1/3 of tongue Cranial Exit – Jugular Foramen Associated nuclei: look at slide 69 Motor Nucleus Ambiguous and salvatory nucleus Sensory Nucleus Solitaries All located in medulla CN X (Vagus) Main parasympathetic nerve Motor Fibers Function – Parasympathetic to smooth muscle of trachea, bronchi, digestive tract, cardiac muscle Motor to constrictors of pharynx, intrinsics of larynx, muscles of palate, muscles in upper 2/3rds of esophagus Sensory Fibers Function Sensation from auricle, external acoustic meatus, and dura of posterior cranial fossa Sensation from base of tongue, pharynx, larynx, trachea, bronchi, heart, esophagus, stomach, and intestine Taste from epiglottis and palate Cranial Exit – Jugular Foramen  CN X: Vagus Nerve Associated nuclei: look at slide 69 Motor Motor Nucleus of Vagus Nucleus Ambiguous and salvatory nucleus Sensory Nucleus Solitaries All located in the medulla Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.2  CN XI (Spinal Accessory Nerve) Motor Function – Motor to An accessory part of the vagus nerve sternocleidomastoid and trapezius Somatic motor function of pharynx, Associated with motor neurons in larynx, neck muscles upper cervical ventral horn. Spinal root Cervical root Cranial Exit – Jugular foramen  CN XII: Hypoglossal Nerve Runs inferior to the tongue Innervates the tongue muscles Hypoglossal nuclei Nerve exits preolivary sulcus upper medulla Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Table 14.2 Clinical Case A 59 year old male was involved in a car accident 4 days ago. He sustained fractures of the skull, bilateral femurs, and the right tibia. He is also complaining of double vision. Further examination revealed the following: Normal cognition, language, memory, and somatosensation Normal autonomic functions including the pupillary and accommodation reflexes. Unable to look downward and outward at the same time with the right eye. All other eye movements are Normal. Questions What is the most likely structure involved in this case? A) CN II B) CN III C) CN IV D) CN VI Application of Material CN IV (Trochlear Nerve) innervates the superior oblique muscle of the eye. Superior Oblique Muscle moves the eye downward and outward. CN II (Optic) controls vision at the retinal level – in this case the patient has no specific vision issues other than eye movement CN III (Oculomotor) control muscle that move the eyelid superiorly, turns eyeball upward, downward and medially, pupillary and accommodation reflexes CN VI (Abducens) controls the lateral rectus to turn eye laterally.