Cranial Nerves PDF

Cranial Nerves Course Objectives Nervous: Describe how the body communicates with itself by identifying anatomical structures and tracing pathways of the nervous system in order to aid in medical diagnoses when these systems are compromise...

Cranial Nerves Course Objectives Nervous: Describe how the body communicates with itself by identifying anatomical structures and tracing pathways of the nervous system in order to aid in medical diagnoses when these systems are compromised. Lecture Learning Objectives 1. Describe the general 5. Recall the primary function(s) organization of cranial nerves and cranial exit for each cranial and related structures, focusing nerve on the role of nerve fibers 6. Visually identify the gross (axons), nuclei, and ganglia anatomical structures associated 2. List and define the five functional with each cranial nerve components carried by cranial (identified by ) nerves 7. Relate conditions caused by 3. List the four cranial ganglia damage to specific cranial nerves associated with visceral motor innervation 4. Visually identify the 12 cranial nerves  LO 1 Cranial Nerves: Introduction 12 pairs Numerically ordered using roman numerals Which motor pathway travels through cranial nerves? How is sensory information from head and neck transmitted? Sensory and motor communication carried within CNs will synapse on cranial nerve nuclei Nuclei for all CN are in brainstem, except CN I and II Travel through openings in crania and are covered with protective CT continuous with meninges Communication occurs between cranial nerves E.g., nerves may begin as sensory, but receive motor fibers along its course  LO 2 Cranial Nerve Functions Cranial nerves carry one or more of the following five main functional components Motor fibers (efferent) 1. Somatic motor- to voluntary muscles 2. Visceral motor- involuntary muscles (autonomic) Sensory fibers (afferent) 3. Somatic sensory- general sensation (touch, pressure, heat, cold) from skin and mucous membranes 4. Visceral sensory- visceral sensation from carotid body and carotid sinus, pharynx, larynx, trachea, bronchi, lungs, heart and GI tract (autonomic) 5. Special sensory- taste, smell, vision, hearing, and balance  LO 4 Cranial Nerve Location All CN I- Olfactory CN II- Optic CN III- Oculomotor CN IV- Trochlear CN V- Trigeminal Pons CN VI- Abducent CN VII- Facial Medulla CN VIII- Vestibulocochlear CN IX- Glossopharyngeal CN X- Vagus CN XI-Accessory Spinal CN XII- Hypoglossal Cord  CN I through IV Big Picture CN I- Olfactory– Smell CN III- Oculomotor- Most eye movement CN II- Optic- Vision CN IV- Trochlear- Inferolateral eye movement via superior oblique m. Abducent- lateral eye movement via lateral rectus m.  LO 5-7 CN I- Olfactory Function: Olfactory bulb Special sensory: smell Synapse: olfactory bulb Olfactory tract Cribriform foramina with Anatomy olfactory Olfactory nerves nerves Cribriform foramina Lateral wall of Olfactory bulb nasal cavity Olfactory tract Condition caused by damage: Anosmia- partial or total loss of smell  LO 5-7 CN II- Optic Function: Special sensory: vision Optic nerve Synapse: ganglion cells in innermost layer of eye, Optic chiasm the retina Optic tract Anatomy: Optic nerve Optic canal Optic Optic chiasm canal Optic tract Conditions caused by damage: Anopsia (visual defects)  LO 5-7 CN III- Oculomotor Superior orbital fissure Function: Somatic motor - 4/6 extrinsic eye muscles (medial, superior, CN III nucleus and inferior rectus, inferior oblique); elevates eyelid CN III (levator palpebrae superioris) Midbrain Visceral motor: Pupil constriction Pons Change lens shape Synapse: ciliary ganglion Medulla Anatomy: 1. Superior orbital fissure  LO 5-7 CN III- Oculomotor Conditions caused by damage: Difficulties with eye motor function Ptosis (upper eyelid droop) Paralysis of most eye muscles leading to strabismus (eyes not parallel/deviated) Diplopia (double vision) Focusing difficulties Pupil dilation  LO 5-7 CN IV- Trochlear Superior orbital fissure Function: Somatic motor CN IV nucleus 1/6 extrinsic eye muscles (superior oblique) Turns eye inferolaterally CN IV Midbrain Anatomy: Superior orbital fissure Pons Conditions caused by damage: Medulla Paralysis of superior oblique Strabismus Diplopia  LO 5-7 CN VI- Abducens Function: Somatic motor 1/6 extrinsic eye muscles Midbrain (lateral rectus)- Turns eyeball laterally Anatomy: Pons Superior orbital fissure Lateral rectus muscle Medulla Conditions caused by damage: CN VI Diplopia caused by nucleus paralysis of lateral rectus limiting eye movements CN VI laterally CN V (Trigeminal), VII (Facial), and VIII (Vestibulocochlear)  CN V, VII and, VIII Big Picture CN V- Trigeminal Facial Sensory for face, scalp, and Movement of face and scalp anterior 2/3 of tongue Muscles of facial expression Movement in glands (2/3 of salivary Muscles of mastication glands, lacrimal) Taste on anterior 2/3 of tongue Vestibulocochlear Hearing and balance  LO 5-7 CN V- Trigeminal Function: Principal somatic sensory for Ophthalmic head nerve Trigeminal ganglion Trigeminal ganglion Trigeminal Three divisions nerve Ophthalmic – superior orbital fissure → supraorbital foramen Maxillary – Foramen rotundum → infraorbital foramen Mandibular - foramen ovale +Somatic motor Mandibular Maxillary nerve nerve All 4 cranial ganglia area associated with divisions of CN V  Trigeminal LO 5-7 ganglion CN V- Trigeminal CN V1 CN V1- Ophthalmic Principal sensory Function: nucleus Somatic sensory Cornea of eye Skin of forehead, scalp, eyelids, nose, superior nasal cavity, and paranasal sinuses (sphenoidal and frontal) Anatomy: Superior orbital fissure → supraorbital foramen  Trigeminal LO 5-7 CN V- Trigeminal ganglion CN V2- Maxillary Principal Function: Foramen CN V2 sensory rotundum nucleus Somatic sensory Skin of face over maxilla: upper lip, maxillary teeth Posterior nasal cavity Maxillary sinuses and palate Anatomy: Foramen rotundum → infraorbital foramen  Trigeminal LO 5-7 CN V- Trigeminal ganglion CN V3- Mandibular Principal sensory Function: CN V3 nucleus Somatic sensory Skin over mandible: lower lip, side of head, mandibular teeth Temporomandibular join Anterior 2/3 of tongue Somatic motor Motor to muscles of mastication, Foramen mylohyoid, anterior belly of ovale digastric, tensor veli palatini, tensor typani Anatomy: Foramen ovale  Trigeminal LO 5-7 CN V- Trigeminal ganglion CN V3- Mandibular Motor Function: CN V3 nucleus Somatic sensory Skin over mandible: lower lip, side of head, mandibular teeth Temporomandibular join Anterior 2/3 of tongue Somatic motor Motor to muscles of Foramen mastication, mylohyoid, ovale anterior belly of digastric, tensor veli palatini, tensor typani Anatomy: Foramen ovale  LO 5-7 CN V- Trigeminal Conditions caused by damage: Trigeminal neuralgia - intense, pulsating pain resulting from inflammation of the sensory components of CN V CN VII (Facial)  LO 5-7 CN VII- Facial Nerve Function: Geniculate Somatic motor- muscles of facial ganglion expression Visceral motor- glands Special sensory- taste CN VII Somatic sensory- very limited entering internal acoustic meatus Nerve travels through internal acoustic meatus, branch and travel through various openings Geniculate ganglion  LO 5-7 CN VII- Facial Nerve Function: Somatic motor 2 Motor to muscles of facial expression and scalp, stylohyoid, and posterior belly of digastric 3 Anatomy: Facial nerve Internal acoustic meatus -> 4 exiting the stylomastoid foramen stylomastoid 1. Posterior auricular branch foramen 2. Temporal branches 1 3. Zygomatic branch 4. Buccal branch 6 5. Mandibular branch 5 6. Cervical branch  LO 5-7 CN VII- Facial Nerve Location of Geniculate ganglion lacrimal gland Greater petrosal CN VII Function: nerve Visceral motor Pterygopalatine Innervation to 2/3 salivary glands ganglion (submandibular and sublingual) lacrimal gland in eye (tears) Synapse: Pterygopalatine ganglion→ lacrimal Submandibular ganglion → submandibular and sublingual glands Anatomy: Greater petrosal nerve Chorda tympani Pterygopalatine ganglion Chorda tympani Submandibular Submandibular ganglion ganglion Salivary glands  LO 5-7 CN VII- Facial Nerve Function: Geniculate ganglion Special sensory Tastes from anterior 2/3 of tongue via chorda tympani CN VII nerve Anatomy: Geniculate ganglion Chorda tympani  LO 5-7 CN VIII- Vestibulocochlear Vestibular and cochlear branches Vestibular and cochlear branches Function: Special sensory: Vestibular/balance Spiral ganglion Special sensory: Cochlear/hearing Internal acoustic meatus Anatomy: Vestibular nuclei Internal acoustic meatus Conditions caused by damage: Vestibular lesions: loss of Cochlear/spiral ganglia balance, nausea, vomiting, and Vestibular ganglion Vestibular dizziness CN VII ganglion Cochlear lesion: deafness Medulla CN VIII  CN IX and X Big Picture Glossopharyngeal (tongue/throat) Vagus Posterior structures (compared to Motor to “throat” Visceral and somatic to pharynx, Facial) larynx, esophagus Aids in swallowing (stylopharyngeus Sensory to ear structures and superior constrictor) Visceral motor and sensory to 1 salivary gland most thoracic and abdominal Taste and somatic sensory to organs posterior tongue Monitors blood via carotid body/sinus  LO 5-7 CN IX- Glossopharyngeal CN VII Passes through jugular foramen Forms superior and inferior ganglia Functions: Somatic motor- swallowing Visceral motor- 1/3 of salivary glands Special sensory- taste to posterior 1/3 of tongue Jugular Somatic sensory- posterior 1/3 of foramen tongue, soft palate and pharynx Visceral sensory- carotid body and sinus- structures on carotid artery CN IX to sense O and CO in blood 2 2  Lesser LO 5-7 CN IX- Glossopharyngeal Otic petrosal nerve CN IX ganglion Somatic motor– aids in swallowing via superior pharyngeal muscles (stylopharyngeus and superior Parotid gland constrictor muscles) Superior Visceral motor: Parotid salivary and inferior gland ganglia Travels though middle ear, lesser petrosal nerve Synapse in otic ganglion  Lesser LO 5-7 CN IX- Glossopharyngeal Otic petrosal nerve CN IX ganglion Sensory will synapse in brain stem nuclei Special sensory Taste to posterior 1/3 of tongue; synapse in Parotid brainstem nuclei gland Somatic sensory Posterior 1/3 of tongue, soft palate and pharynx; synapse in brainstem nuclei Superior and inferior Visceral sensory ganglia Carotid body and sinus- structures on carotid artery to sense O2 and CO2 in blood (chemoreceptors and baroreceptors) Synapse in brainstem nuclei Conditions caused by damage: Reduces salivary secretion Loss of taste sensation on posterior 1/3 of tongue  LO 5-7 CN X- Vagus Exit via jugular foramen Somatic motor Most pharyngeal and laryngeal muscles; superior 2/3 of esophageal muscle Visceral motor Smooth muscle and glands of heart, lungs, larynx, trachea, and most abdominal organs Synapse: Intrinsic ganglia on/in/near viscera  LO 5-7 CN X- Vagus Somatic sensory Nucleus ambiguus External acoustic meatus, eardrum, and pharynx CN X Visceral sensory Jugular foramen Sensation from pharynx, larynx, carotid bodies, heart, lungs, most abdominal organs Superior and inferior ganglia Synapse in brainstem nuclei CN X Conditions caused by damage: Difficulty swallowing or impaired GI system mobility Paralysis leading to laryngeal problems Hoarseness, monotone voice, or complete loss of voice  CN XI and XII Big Picture Accessory Hypoglossal Motor to sternocleidomastoid and Motor to tongue trapezius  LO 5-7 CN XI- Spinal Accessory Ascend from cervical spinal cord through foramen magnum, temporarily joins CN X as it exits the jugular foramen Function: Somatic motor Sternocleidomastoid and trapezius Anatomy: Foramen magnum Jugular foramen Conditions caused by damage: Paralysis to trapezius and sternocleidomastoid Difficulty elevating shoulder (trapezius) or turning head to opposite side (sternocleidomastoid)  LO 5-7 CN XII CN XII- Hypoglossal Hypoglossal canal CN XII Function: nucleus Somatic motor Motor to most tongue muscles Anatomy: Hypoglossal canal Conditions caused by damage: Swallowing and speech difficulties due to impaired tongue movement If single side is affected, protruded tongue will deviate to side of nerve damage  Cranial foramina LO 5 and nerves CN I CN II Cribriform plate- CN I Optic canal- CN II CN V2 CN V3 CN III, IV, V1, VI Superior orbital canal – CN III, IV, V1, VI Movement to the eye and ophthalmic division of V CN VII, VIII Foramen rotundum- CN V2 Foramen ovale- CN V3 CN XII CN IX, X, XI Internal acoustic meatus- CN VII, VIII Jugular foramen- CN IX, X, XI Hypoglossal canal- XII Internal base of crania