Cranial Nerves PDF

Name # Type Location of Nuclei Foramen Pathway Function...

Name # Type Location of Nuclei Foramen Pathway Function Pathologies Notes Shortest cranial nerve (in length) 1. Olfactory receptors 2. Olfactory nerve Hyperosmia - ↑ sense of smell olfactory epithelium 3. Olfactory foramina – cribriform plate Anosmia - loss sense of smell - superior part of nasal cavity SENSORY Olfactory I (1) Sensory N/A Olfactory foramina – in the cribriform plate 4. Olfactory bulbs Hyposmia - ↓ ability to smell - inferior surface of the cribriform plate 5. Olfactory tracts - along the superior nasal concha Smell 6. Primary olfactory area (temporal) + limbic system (emotions) + hypothalamus (satiety) 7. Frontal lobe (orbitofrontal area) ***Olfactory sensations are the only sensations that reach the cerebral cortex without first synapsing in the thalamus *** 1. Rods + cones then to bipolar cells → ganglion cells Photoreceptors - CONES and RODS 2. Optic nerve Cones: bright light, colour vision, high acuity, concentrated in center of retina 3. Optic foramen/canal Rods: dim light, no colour, low acutiy, concentrated in periphery, sensitive SENSORY Optic II (2) Sensory N/A Optic canal – Optic Foramen 4. Optic chiasm - where optic nerve ends (50% cross here) Anopia - blindness 5. Optic tract Sight Bipolar cells: lateral connections involved in modifying signals 6. Lateral geniculate nucleus (thalamus) Ganglion cell layer: exit eye as the OPTIC NERVE 7. Primary visual area (occipital lobe #17) pituitary gland - underneath optic chiasm MOTOR Motor Pathway Moves the eyes - 4 extrinsic eye mm 1. motor nucleus - midbrain Superior Rectus 2. superior orbital fissure Inferior Rectus 3. superior branch OR inferior branch Medial Rectus 4. superior branch - superior rectus, levator palpabrae superioris How is pupil diameter regulated? Inferior Oblique Strabismus - lazy eye 4. inferior branch - medial rectus, interior rectus, inferior oblique mm Ptosis - Drooping of upper eyelid Oculomotor * III (3) Motor + Autonomic Midbrain Superior Orbital Fissure Open upper eyelid (intrinsic eye mm) - Levator Palpabrae Movement of eyeball downward + outward on damaged side Contraction of the circular muscles causes constriction of the pupil Superioris Loss of accommodation for near vision Diplopia - Double vision Contraction of the radial muscles cause dilation of the pupil Autonomic Pathway AUTONOMIC 1. Motor nucleus - midbrain 2. superior orbital fissure Ciliary muscle - adjusts lens for near vision "accomodation" 3. inferior branch 4. ciliary ganglion Circular mm of Iris - pupil constriction 5. ciliary muscle, circular muscle of iris 1. Trochlear nucleus in midbrain MOTOR Smallest cranial nerve (in diameter) Strabismus - lazy eye (inward or outward) Trochlear IV (4) Motor Midbrain Superior Orbital Fissure 2. Superior orbital fissure Diplopia - double vision 3. Superior oblique mm of eyeball Eyes – superior oblique mm The only one that arises from the posterior brain stem Ophthalmic branch: 1. Sensory from upper 1/3 of face (forehead ect.) 2. Superior orbital fissure Ophthalamic branch - Superior Orbital fissure 3. Ophthalmic branch 4. Trigeminal ganglion 5. Pons Maxillary branch: Largest cranial nerve (in diameter) 1. Sensory from middle 1/3 of face (upper teeth ect.) 2. Foramen rotundum Maxillary – Foramen rotundum Sensory – Face sensation of the tongue (ant 2/3) In mandibular branch 3. Maxillary branch Trigeminal V (5) Sensory + Motor Pons 4. Trigeminal ganglion Trigeminal Neuralgia - Supply muscles of mastication 5. Pons Motor – Mastication (masseter mm, temporalis mm) - These motor neurons mainly control chewing Mandibular branch: 1. Sensory from lower 1/3 of face (jaw ect.) 2. Foramen ovale 3. Mandibular branch Mandibular – Foramen ovale 4. Trigeminal ganglion 5.Pons Motor pathway - mastication as well (mandibular branch) & sensory of the tongue Eye can't move laterally beyond midpoint and eyeball is usually directed medially 1. Abducens nucleus in pons MOTOR Abducens VI (6) Motor Pons Superior Orbital Fissure 2. Superior orbital fissure This leads to: 3. Lateral rectus mm of eyeball Eyes – lateral rectus mm Strabismus and Diplopia Sensory Pathway: 1. Taste buds of anterior 2/3 of tongue 2. Stylomastoid foramen 3. Geniculate ganglion Facial nerve goes underneath parotid gland - can cause problems Sensory – 1/3 of external ear, taste (2/3 of tongue) 4. Pons 5. Thalamus 6. Gustatory area of cerebral cortex (the insula) smallest skeletal muscles = stapedius (clamp down so there are less vibrations) Also sensory axons from skin in ear canal (touch, pain, temp) Nasal glands (mucus) Bells Palsy Palatine glands (mucus in mouth) Facial * VII (7) Sensory + Motor + Autonomic Pons Stylomastoid Foramen Motor Pathway Is a condition involving the facial nerve – facial nerve paralysis Submandibular glands (salivary glands) 1. Nucleus in pons One of the most common neurological conditions Sublingual glands (salivary glands) Motor – facial expression 2. Stylomastoid foramen 3. Facial expression muscles, stylohyoid mm, posterior digastric mm, stapedius mm Taste: cranial nerves Autonomic Pathway 7 - anterior 2/3 1. Nucleus in pons 9 - posterior 1/3 2. stylomastoid foramen 10 - epigllotis & pharynx Autonomic – mucus, salivation, lacrimation 3. pterygopalatine ganglion OR submandibular ganglion 4. pterygopalatine ganglion - lacriminal glands, nasal gland, palatine, gland 4. submandibular ganglion - submandibular glands, sublingual glands Vestibular Branch Vertigo 1. Balance portion of ear Equilibrium/Balance Ataxia - loss of motor control 2. Vestibular ganglion Nystagmus - eyes make rapid, repetitive, uncontrolled movements 3. Vestibular nuclei in pons + medulla 2 Branches Vestibulocochlear VIII (8) Sensory Pons/Medulla Auditory Canal – Internal auditory meatus Cochlear Branch - Vestibular branch (balance) 1. Spiral organ (organ of corti) in cochlea of internal ear - Cochlear branch (hearing) Tinnitus - Ringing in ears 2. Spiral ganglion More of a chronic problem – big question mark with this condition 3. Internal acoustic meatus Hearing 4. Cochlear nuclei in medulla Deafness 5. Thalamus (medial geniculate) 6. Primary auditory area Sensory Pathway: 1. taste buds on posterior 1/3 of tongue Glossopharygeal Neuralgia: Recurrent attacks of severe pain in the nerve distribution SENSORY 2. Proprioceptors from some swallowing muscles 1/3 tongue taste, 1/3 of external ear - Posterior pharynx, tonsils, back of tongue, middle ear 3. Baroreceptors in carotid sinus that monitor BP + baroreceptors 4. Chemoreceptors in carotid sinus +chemoreceptors Cause: 5. External ear to convey touch, pain, heat and cold +proprioception Nerve compression - Rare, more common in men – usually after 40 6. Superior and inferior ganglia (don’t worry about these) 7. Jugular foramen (2nd biggest foramen) Get paroxysmal attacks of unilateral brief, excruciating pain 8. Medulla Dysphagia – difficulty swallowing - Like in trigeminal neuralgia Aptyalia – lack of salivation Motor Pathway Loss of sensation in throat – proprioception Glossopharyngeal * IX (9) Sensory + Motor + Autonomic Medulla Jugular Foramen 1. Nuclei in medulla MOTOR - swallowing Ageusia – lack of taste Occurs spontaneously or are precipitated by certain movements 2. Jugular foramen Glossopharyngeal Neuralgia - Chewing, swallowing, talking, sneezing 3. Stylopharyngeus muscle: helps elevate your pharynx when you swallow Pain lasts seconds to a few minutes Autonomic Pathway Usually begins in tonsil area or at base of tongue and may radiate to ipsilateral ear 1. Inferior salivary nucleus in medulla 2. Jugular foramen Distinguished from trigeminal neuralgia by: AUTONOMIC - salivation (parotid gland) 3. Otic ganglion - Location of pain 4. Parotid gland - swallowing or touching the tonsils with an applicator triggers pain SENSORY PATHWAY 1. Skin of external ear for touch, pain, heat and cold 2. Taste buds in epiglottis and pharynx 3. Proprioceptors in mm of neck and throat 4. Baroreceptors in carotid sinus & chemoreceptors in carotid & aortic bodies Sensory – HR, BP, 1/3 external ear 5. Visceral sensory receptors in most organs of thoracic & abdominal cavities (hunger, fullness ect.) 6. Superior and inferior ganglia (don’t worry about these) 7. Jugular foramen 8. Medulla Longest of our cranial nerves (CNX) in length - "the wandering nerve" Vagal paralysis Vagus * X (10) Sensory + Motor + Autonomic Medulla Jugular Foramen MOTOR PATHWAY Dysphagia Vagal paralysis 1. Medulla Tachycardia Interruptions of sensations from many organs in thoracic and abdominal cavities 2. Jugular foramen Motor – swallowing, talking 3. Muscles of the pharynx, larynx & soft palate (swallowing, vocalization, coughing) Vasovagal response (negative) AUTONOMIC PATHWAY 1. Medulla 2. Jugular foramen 3. Muscles: Autonomic – smooth muscle of guts, lungs, heart Smooth muscle of lungs, Cardiac mm, Glands of GI tract, Smooth mm of respiratory passageways, Esophagus, Stomach, Gallbladder, Small intestine, Most of large intestine 1. Motor axons from anterior grey horn of C1 – C5 MOTOR Its not really a cranial nerve – more like a spinal nerve N/A Jugular Foramen 2. Ascend through foramen magnum Accessory XI (11) Motor n/a (anterior grey horn C1 - C5) First enters skull through foramen magnum 3. Exit through jugular foramen SCM & trapezius cause it goes from C1 – C5 up to the head and then back down to the SCM & Trapezius 4. SCM & trapezius Difficulty chewing 1. Hypoglossal nucleus in the medulla MOTOR Hypoglossal XII (12) Motor Medulla Hypoglossal Foramen 2. Hypoglossal canal Dysarthia – difficulty speaking (jaw/peripheral nerve problem) 8 muscles in the tongue 3. Muscles of tongue Tongue movement Dysphagia - difficulty swallowing Midbrain Pons Pons/Medulla Medulla Oculomotor Trigeminal Vestibulocochlear Glossopharyngeal Trochlear Abducens Vagus Facial Hypoglossal Help with swallowing Help w/ salivation Help with speaking 9 - glossopharyngeal (swallowing) 7 - facial (others) 5 - trigeminal (mastication mm) 10 - vagus (swallowing) 9 - glossopharygeal (parotid) 7 - facial (facial expression mm) 12 - hypoglossal (tongue mvmnt) 9 - glossopharyngeal (swallowing) 10 - vagus (swallowing, vocalization) 12 - hypoglossal (tongue mm) Autonomic Involved with Taste Contribute to External Ear 10 - vagus 7 - facial (ant 2/3) 7 - Facial (1/3) - ear canal 9 - glossopharyngeal 9 - glossopharygeal (post 1/3) 9 - glossopharyngeal (1/3) 7 - facial 10 - vagus (epiglottis and pharynx) 10 - vagus (1/3) 3 - oculomotor Name # Type Location of Nuclei Foramen Pathway Function Pathologies Notes Shortest cranial Nerve CN I - Olfactory Longest cranial Nerve CN X - Vagus Thinnest cranial Nerve CN IV - Trochlear Thickest cranial Nerve CN V - Trigeminal