Cranial Nerves Revision PDF

Cranial nerves ...

Cranial nerves  Enters orbit through superior orbital fissure Eye/eyelid movement - 4/6 ocular muscles of the eye Arise from brain stem Motor Eye movement - Anosmia = Oculomotor III Damage: superior oblique Sensory muscle Trochlear IV Olfactory I Sense of smell Loss of smell Arise from brain stem Oculomotor nerve palsy Dropping eyelids Motor Damage: Causes: Unable to move eye Double vision Intracranial pressure increase Arise from cerebrum Damage: Enter orbit through superior (Microvascular damage, Dilated pupils Head tilts to Loss of smell orbital fissure of sphenoid Causes: diabetes, hypertension) Pass into olfactory bulb compensate Distorted smell Intracranial pressure increase Abnormal taste perception (Diabetes, MS, infection, trauma) Causes: Trauma 2 optic nerves join at optic chiasma Tumour 3 branches; Arise from cerebrum Enters orbit - superior Infection Lacrimal nerve orbital fissure Extends from midbrain to medulla Frontal nerve Sensory Damage: Smallest division Optic II Nasociliary nerve Loss of vision; full or partial Sensory Vision Arise from brain stem (pons) Ophthalmic Causes: Largest cranial nerve Trauma, tumour, glaucoma Depends on 3 divisions - join at or crush injuries Mandibular teeth and supporting structures Maxillary teeth and supporting structures location of nerve Trigeminal V Gasserion ganglion Mucosa anterior 2/3 tongue and floor of mouth Hard and soft palate damage Maxillary Skin of lower face Sensory Maxillary sinus Eating, speaking and swallowing Parts of temporal region and outer ear Sensory & motor Mandibular Most of nasal cavity Exits via Skin overlying middle part of face Intrinsic & extrinsic muscles of tongue foramen ovale Exits via foramen rotundum (NOT palatoglossus) Largest division Passes into pterygopalatine Muscles of mastication fossa where it divides Zygomatic Cranial Nerves Motor Damage: Mylohyoid Posterior trunk: Infraorbital — Wasting/deviation of tongue to affected side Anterior belly of digastric Anterior trunk: Auriculotemporal Posterior superior alveolar — Difficulties eating, speaking and swallowing Tensor veli palatini Masseteric Hypoglossal XII Lingual Pterygopalatine 12 pairs Tensor tympani Deep temporal Causes: Inferior alveolar Arise from brain stem Lateral pterygoid Tumours, infections, traumas, radiation, stroke Long buccal Mylohyoid Clinical relevance Mental nerve Incisive nerve Damage: Causes: Vestibular Neuritis Possible — Vertigo reactivation of — Loss of equilibrium Arise from brain stem Herpes simplex — Nausea & vomiting Enters orbit through superior Arise from Spinal part orbital fissure brain stem Motor Vestibulocochlear VIII Damage: Causes: Damage: Damage: (Auditory nerve) Labyrinthitis Inflammation of Eye deviates medially Muscles - Trapezius & Sternocleidomastoid Sensory Arise from brain stem — Shoulder pain & weakness — Hearing loss membranous Double vision Accessory XI Hearing - cochlear nerve — Tinitis labyrinth — Limited upper arm movement Muscles of soft palate Special senses Causes: Abducens VI Motor — Asymmetrical shoulder Balance - vestibular nerve Downward pressure Cranial part on brain stem Lateral eye movements - lateral Causes: rectus muscle Surgery, trauma, radiation, over-use. Special sensory - taste to anterior 2/3 tongue Sensory - external ear Parasympathetic efferents - sublingual & submandibular salivary glands, lacrimal, Muscles of facial expression including platysma Stylohyoid muscle Sensory and motor root Greater petrosal nerve Damage: 1 in 100,000 nasal, palatine and pharyngeal glands Oropharynx Posterior belly of digastric travel through internal Glossopharyngeal Larynx, mucosa Stapedius (ear) acoustic meatus to facial Nerve to stapedius Muscles of trachea, bronchi, neuralgia pharynx, soft Taste posterior Posterior 1/3 Nervus intermedius canal Skin; back of ear, abdominal organs & GI tract — Loss of gag reflex Stylopharygeus palate & 1/3 tongue tongue Chorda tympani larynx, pharynx, — Sharp pain throat, muscle oesophagus epiglottis. tongue or tonsils Special sensory Sensory & Motor Parasympathetic Intracranial - course of the nerve through the Minor role in taste Sensory & Motor Causes: Facial VII cranial cavity and the cranium Facial nerve exist facial canal Sensory & Motor Vagus X Special sensory Neuromuscular Glossopharyngeal IX and skull via stylomastoid compression of Parasympathetic foramen nerve Arise from brain stem Extra cranial - course of nerves outside the cranium, Arise from brain stem Arise from brain stem Parotid gland Damage: through face and neck Between pons and medulla Facial nerve passes through parotid gland and terminate into 5 branches: — Deviation of uvula away from damaged side Temporal — Hoarse voice Zygomatic — Trouble drinking liquids Extracranial branches: Causes: Buccal — Loss of gag reflex Posterior auricular nerve Trauma, tumors, surgery, infections, chronic conditions, stress. Mandibular — Ear pain Posterior belly of digastric muscle Cervical Stylohyoid muscle  Conjunctiva Cornea Eyeball Orbit Pterygo-maxillary fissure = Forehead Ethmoid & frontal sinuses Posterior surface of maxillary and Trigeminal nerve nucleus = pterygoid process of sphenoid 3 branches; Specialised clusters of neurones Extends from midbrain to medulla Lacrimal nerve Enters orbit - superior bone. Frontal nerve Sensory orbital fissure Connects infratemporal fossa with Arise from brain stem (pons) Nasociliary nerve pterygopalatine fossa. Largest cranial nerve Ophthalmic Pterygomaxillary fissure leads into Maxillary teeth and supporting structures it Smallest division Hard and soft palate Maxillary sinus Most of nasal cavity Skin overlying middle part of face Mandibular teeth and supporting structures Mucosa anterior 2/3 tongue and floor of Muscles of mastication Sensory mouth Mylohyoid Skin of lower face Anterior belly of digastric Parts of temporal region and outer ear Tensor veli palatini Maxillary Tensor tympani Trigeminal Nerve V Exits skull via foramen rotundum Sensory and motor Enters orbit through inferior orbital fissure Passes into pterygopalatine Divides into; Sensory innervation to temple Masseteric nerve (motor) fossa Zygomaticotemporal nerve & 1st branch of anterior trunk Mandibular Zygomaticofacial nerve Innervates skin on cheeks Crosses between coronoid process and condyle Largest of 3 divisions Divides into 4 branches; Articulate branch to TMJ Zygomatic Elevates mandible Enters orbit through inferior orbital fissure Infraorbital Leaves skull via foramen ovale Leaves orbits at Infraorbital foramen Posterior superior alveolar I Terminal Divides into; Pterygopalatine Deep temporal nerve (motor) branches Middle & anterior Palpebral nerve - Elevates the mandible Small anterior trunk Greater palatine superior alveolar lower eyelid skin Large posterior trunk Branches of nerve before division; Supplies much of mucosa of hard palate & palatal nerve branches Meningeal branch gingivae, except incisive papilla. Labial nerve - skin, Lateral pterygoid nerve (motor) Nerve to medial pterygoid muscle Anterior - oral mucosa upper lip, Passes through greater palatine canal. Nasal nerve - May run part way with long buccal incisors & Middle - maxillary labial gingivae, side of nose Depresses the mandible canines premolars & MB anterior maxillary skin root 1st molar Medial pterygoid nerve (motor) teeth Enters deep surface of muscle Lesser palatine nerve Long buccal nerve (sensory) Also supplied tensor tympani & Passes through greater palatine canal — Branches to supply buccal Only sensory branch of anterior trunk Auriculotemporal nerve (sensory) tensor veli palatini lesser palatine foramen gingivae of maxillary molars Branches to skin of cheek 1st branch of posterior trunk Elevates the jaw Supplies soft palate - sensory Leaves through pterygomaxillary fissue Pierces buccinator to supply buccal Autonomic to parotid gland Runs onto tuberosity of maxilla sulcus and buccal gingivae of Sensory to skin of temple, ear, scalp, Pierces bone to supply maxillary mandibular molars & premolars. middle ear mucosa and TMJ. sinus and molar teeth (3rd & 2nd) Nasopalatine nerve and DB and P root of 1st molar. Inferior alveolar nerve (sensory & motor) Enters cavity through sphenopalatine foramen Enters via mandibular foramen Passes through incisive canal on hard palate Descends deep behind lingual nerve Supplies; part of nasal septum, oral mucosa Lingual nerve (sensory) Supplies mandibular molars, around incisive papilla. 2nd branch of posterior trunk premolars & supporting structures Parasympathetic fibres for submandibular 3 branches; and sublingual glands Supplies mucosa anterior 2/3 dorsum of tongue, ventral surface of tongue, floor of Mental nerve (sensory) mouth, lingual gingivae of mandibular Mylohyoid nerve (motor) Supplies skin of chin, lower lip, labial teeth. Gives off just before gingivae of anterior mandibular teeth mandibular foramen Supplied Mylohyoid muscle ID nerve blocks can spread to lingual & anterior belly of digastric Incisive nerve (sensory) nerve and cause numbness of tongue due Depresses mandible and Supplies mandibular incisors & canines elevates hyoid. to close proximity.  Nerve to stapedius Greater petrosal nerve Motor fibres to stapedius Parasympathetic fibres to; nasal, palatine muscle of middle ear and pharyngeal mucous glands, paranasal Dampens loud noises sinuses and lacrimal gland for tear production If the causes cannot be found to damage of the facial nerve, the term Bell’s Palsy is usually used Geniculate ganglion Chorda tympani (Idiopathic) Special sensory to anterior 2/3 of tongue (taste) These roots fuse to form facial nerve Parasympathetic fibres to submandibular & sublingual glands Large motor root Small sensory root Travels with lingual nerve Between pons and medulla Begins as 2 roots - travel through internal acoustic meatus into facial canal Arises from brain stem Intracranial - course of the nerve through the cranial cavity and the cranium Facial Nerve Paralysis/extremely weakened Dry eyes - reduced lacrimal function muscles of facial expression Dry mouth - reduced salivation Loss of taste - anterior 2/3 of tongue Difficulty talking - hyper sensitive to sound VII Responsible for raising hyoid bone The facial nerve exists the facial canal and cranial via the stylomastoid Posterior belly of Stylohyoid Intracranial lesions the digastric muscle foramen Occur in intracranial course, proximal to stylomastoid foramen muscle Affects parasympathetic, sensory and motor functions Symptoms depend on location of branches effected Extracranial - the course of the nerve outside the cranium, through the face and neck Damage to Causes Temporal branch Posterior auricular nerve facial nerve External or middle ear infection Crosses zygomatic arch to reach forehead 1st extracranial branch Stroke Supplies; Motor innervation to intrinsic and extrinsic Auricular muscles Main trunk passes through parotid muscles around ear Frontalis gland and terminates into 5 branches Supplies occipital part of occipitofrontalis muscle Orbicularis oculi Corrugator supercilii Innervates motor function to Zygomatic branch muscles of facial expression Cervical branch Upper branch; Passes downwards from lower Extracranial lesions Passes above orbit to supply border of parotid gland Occur in extracranial course, nerve has exited via occipitofrontalis & orbicularis oculi Supplies; stylomastoid foramen Lower branch; Platysma Only motor function affected Passes below orbit to supply lower part of orbicularis oculi and contributes to muscles of upper lip and nose Mandibular branch Causes Emerges lower border of parotid gland Paralysis or severe weakness of Parotid gland pathology - tumour, parotitis, surgery Runs near inferior border of mandible muscles of facial expression Infection of the nerve - herpes virus Buccal branch Supplies; Local anaesthetic - rare Supplies; Depressor labii inferioris Orbicularis oris Depressor anguli oris Buccinator Mentalis Zygomaticus Contributes to innervation of upper lip and nose