Cranial Nerves - College 5 PDF

Chapter 12 Opener Chapter 12 Figure 12.1 Midsagittal View of the Brainstem In Situ Table 12.1 Cranial Nerve Names and Main Functions CN Name Main function(s) CN I Olfactory nerve Olfaction CN II Optic ne...

Chapter 12 Opener Chapter 12 Figure 12.1 Midsagittal View of the Brainstem In Situ Table 12.1 Cranial Nerve Names and Main Functions CN Name Main function(s) CN I Olfactory nerve Olfaction CN II Optic nerve Vision CN III Oculomotor nerve Eye movements; pupil constriction CN IV Trochlear nerve Eye movements CN V Trigeminal nerve Facial sensation; muscles of mastication CN VI Abducens nerve Eye movements CN VII Facial nerve Muscles of facial expression; taste; lacrimation; salivation CN VIII Vestibulocochlear nerve Hearing; equilibrium sense CN IX Glossopharyngeal nerve Pharyngeal muscles; carotid body reflexes; salivation CN X Vagus nerve Parasympathetics to most organs; laryngeal muscles (voice); pharyngeal muscles (swallowing); aortic arch reflexes CN XI Spinal accessory nerve Head turning (trapezius and sternomastoid muscles) CN XII Hypoglossal nerve Tongue movement CN I: Olfactory Nerve Functional Category Function Special somatic sensory Olfaction Figure 18.5 Principal Neurons and Pathways of Olfactory Nerves and Olfactory Bulbs CN I: Olfactory nerve: Olfaction Figure 12.3 Skull Foramina Serving as Cranial Nerve Exit Points (Part 1) Figure 18.6 Central Olfactory Structures and Other Components of the Parahippocampal Gyrus CN II: Optic Nerve Functional category Function Special somatic sensory Vision Figure 11.1 Formation of Images on the Retina (Part 1) Figure 11.1 Formation of Images on the Retina (Part 2) Image on the retina is reversed and inverted o8 Left hemisphere Right hemisphere Figure 11.15 Effects of Lesions in the Primary Visual Pathways (Part 2) Figure 11.15 Effects of Lesions in the Primary Visual Pathways Table 13.1 Actions and Innervation of the Extraocular Muscles Muscle Main actions on the eye Comments Innervation Lateral rectus Abduction Abduction = temporal Abducens nerve (CN VI) (lateral) movement of eye Medial rectus Adduction Adduction = nasal Oculomotor nerve (CN III) (medial) movement of eye Superior rectus Elevation and intorsion Elevation increases with Oculomotor nerve (CN III) abduction; intorsion increases with adduction Inferior rectus Depression and extorsion Depression increases with Oculomotor nerve (CN III) abduction; extorsion increases with adduction Inferior oblique Elevation and extorsion Elevation increases with Oculomotor nerve (CN III) adduction; extorsion increases with abduction Superior oblique Depression and intorsion Depression increases with Trochlear nerve (CN IV) adduction; intorsion increases with abduction Figure 13.1 Extraocular Muscles and Actions (Part 1) Figure 13.1 Extraocular Muscles and Actions (Part 2) Figure 13.1 Extraocular Muscles and Actions (Part 3) Figure 13.1 Extraocular Muscles and Actions (Part 4) CN III, IV, and VI: Oculomotor, Trochlear, and Abducens Nerves Nerve Functional category Function CN III Somatic motor Levator palpebrae superior and all extraocular muscles, except for superior oblique and lateral rectus Parasympathetic Parasympathetics to pupil constrictor and ciliary muscles near vision CN IV Somatic motor Superior oblique muscle; causes depression and intorsion of the eye CN VI Somatic motor Lateral rectus muscle; causes abduction of the eye Figure 12.6 Summary of Cranial Nerve Parasympathetic Pathways Figure 13.9 Actions of the Ciliary Muscle and the Pupillary Muscles (Part 1) Radial muscle Figure 13.9 Actions of the Ciliary Muscle and the Pupillary Muscles (Part 2) Circular muscle  Tarsalis superior muscle (sympathetic nervous system) Ptosis Horner’s syndrome Miosis (pupilconstriction) Figure 13.10 Sympathetic Pathways Causing Pupillary Dilation  Trochlear (IV) palsy Paresis of the superior oblique muscle: (function: depression and intorsion of the eye) CN V: Trigeminal Nerve Functional category Function General somatic sensory Sensations of touch, pain, temperature, joint position, and vibration for the face, mouth, anterior two-thirds of tongue, nasal sinuses, and meninges Branchial motor Muscles of mastication and tensor tympani muscle  CN V: Trigeminal nerve Three divisions: – 1. Ophthalmic division V1 – 2. Maxillary division V2 – 3. Mandibular division V3 Figure 12.7 Trigeminal Nerve (CN V) Trigeminal nerve V  CN V: Trigeminal nerve – General somatic sensory: pain, touch, temperature, joint position, and vibration for face, mouth, anterior two-thirds of tongue, nasal sinuses, meninges – CN IX posterior part of the tongue, pharynx – Branchial motor (small): muscles of mastication and tensor tympani muscle (eardrum tensioner) Figure 12.7 Trigeminal Nerve (CN V) (Part 1) Figure 12.7 Trigeminal Nerve (CN V) (Part 2) Sensation external ear IX: sensation middle ear posterior 1/3 tongue pharynx X: sensation infratentorial dura, pharyngeal sensation V: supratentorial dura External acoustic meatus External acoustic meatus CN V CN X Table 12.6 Analagous Trigeminal and Spinal Somatosensory Systems Main pathway to Main Thalamic Nucleus Sensory modalities thalamus Nucleusa TRIGEMINAL SENSORY SYSTEMS Mesencephalic trigeminal Proprioception — — nucleus Chief trigeminal sensory Fine touch; dental pressure Trigeminal lemniscus VPM nucleus Spinal trigeminal nucleus Crude touch; pain; temperature Trigeminothalamic tract VPM SPINAL SENSORY SYSTEMS Posterior column nuclei Fine touch; proprioception Medial lemniscus VPL Dorsal horn Crude touch; pain; temperature Spinothalamic tract VPL a VPL, ventral posterior lateral nucleus; VPM, ventral posterior medial nucleus. GSA: General Somatic Afferent fibres: pain, touch, temperature from skin Figure 12.8 Trigeminal Sensory System Nuclei and Pathways Dorsal column Propriocept info masticatory muscles Fine touch, dental pressure Spinothalamic tract Crude touch, pain, temperature Trigeminal neuralgia CN VII: Facial Nerve Functional category Function Branchial motor Muscles of facial expression, stapedius muscle, and part of digastric muscle Parasympathetic Parasympathetics to lacrimal glands, and to sublingual, submandibular, and all other salivary glands except parotid Visceral sensory (special) Taste from anterior two-thirds of tongue General somatic sensory Sensation from a small region near the external auditory meatus  N. Facialis N. Trigeminus Breathing, swallowing, speech Figure 12.10 Facial Nerve (CN VII) Facial nerve VII Greater petrosal nerve - sphenopalatine ganglion - postganglionic parasympathetic cells – lacrimal glands and nasal mucosa supplying submandibular and sublingual salivary glands and, together with lingual nerve: taste sensation: 2/3 anterior tongue Chorda tympani (taste) leaves the facial nerve just before the stylomastoid foramen Figure 12.12 Central Taste Pathways bilateral? Figure 12.13 Upper Motor Neuron versus Lower Motor Neuron Facial Weakness CN VIII: Vestibulocochlear Nerve Functional category Function Special somatic sensory Hearing and vestibular sensation Carries special somatic sensory functions of hearing and vestibular sense from structures of the inner ear exits brainstem at pontomedullary junction (cerebellopontine angle) than enters the internal auditory meatus and travels in the auditory canal together with N VII Figure 12.2 Surface Anatomy of the Brainstem and Cranial Nerves (Part 1) Figure 12.14 Superior View of Internal Auditory Canal and Inner Ear Structures Auditory pathways Cochlea: translates the vibrations of auditory sound into impulses the brain can understand Vestibular pathways Utricle and saccule: balance, detection of motion and orientation Semicircular canals: keep the body in balance, by sensing head rotations – Posterior semicircular: touch shoulders with your head – Lateral: look to the left or the right side – Anterior: when nodding your head Figure 12.18 Orientation of Semicircular Canals anterior posterior lateral Figure 12.15 Summary of Vestibular and Cochlear Structures Figure 12.15 Summary of Vestibular and Cochlear Structures (Part 1) Figure 12.15 Summary of Vestibular and Cochlear Structures (Part 2) Figure 12.15 Summary of Vestibular and Cochlear Structures (Part 3) Figure 12.15 Summary of Vestibular and Cochlear Structures (Part 4) Figure 12.16 Central Auditory Pathways (Contralateral) Continue (Bilateral) Figure 12.15 Summary of Vestibular and Cochlear Structures (Part 1) Figure 12.19 Vestibular Nuclei and Vestibular Tracts Figure 12.19 Vestibular Nuclei and Vestibular Tracts utricle, anterior Adjustment of posture, saccule, ant. + lat. muscle tone, and semicircular canals eye position, in response to head posterior saccule, movements in space posterior semicircular canals Figure 12.19 Vestibular Nuclei and Vestibular Tracts Vestibulo-ocular reflex: eye movements adjust for change head position utricle, saccule, Adjustment of posture, semicircular muscle tone, and canals eye position, saccule, in response to head semicircular movements in space canals Balance, extensor tone Control neck and head position CN IX: Glossopharyngeal Nerve Functional category Function Branchial motor Stylopharyngeus muscle Parasympathetic Parasympathetics to parotid gland General somatic sensory Sensation from middle ear, region near the external auditory meatus, pharynx, and posterior one-third of tongue* Visceral sensory (special) Taste from posterior one-third of tongue Visceral sensory (general) Chemoreceptors and baroreceptors of carotid body *Sensation from posterior tongue and pharynx may be considered visceral rather than somatic. Figure 12.20 Glossopharyngeal Nerve (CN IX) Glossopharyngeal nerve CN IX Elevates pharynx during talking and swallowing  Oral cavity (Between hyoid and cricoid) (strottenhoofd) (luchtpijp) (slokdarm) CN X: Vagus Nerve Functional category Function Branchial motor Pharyngeal muscles (swallowing) and laryngeal muscles (voice box) Parasympathetic Parasympathetics to heart, lungs, and digestive tract down to the splenic flexure General somatic sensory Sensation from pharynx, meninges, and a small region near the external auditory meatus Visceral sensory (special) Taste from epiglottis and pharynx Visceral sensory (general) Chemoreceptors and baroreceptors of the aortic arch and gastrointestinal tract Figure 12.21 Vagus (CN X) Vagus Nerve X Parasympathic for gastrointestinal tract Rostral: gustatory Caudal: cardioresp Muscles of palate, pharynx, esophagus, larynx FIGURE 6.13 Sympathetic and Parasympathetic Divisions of the Autonomic Nervous System  (Spleen) Pelvic splanchnic nerve S2-S4 CN XI: Spinal Accessory Nerve Functional category Function Branchial motor Sternomastoid and upper part of trapezius muscle Figure 12.2 Surface Anatomy of the Brainstem and Cranial Nerves (Part 3) Upper 5–6 segments cervical spinal cord  CN XI: Spinal Accessory Nerve Branchial motor: Sternocleidomastoid and upper part of trapezius muscle Lower part trapezius: C3 C4  Sternocleidomastoideus Lower motor neurons of CN XI: weakness of head turning away from the lesion Upper motor neurons of CN XI: deficits in head turning, to the side opposite the lesions (so identical to lower motor neuron lesions) Explanation: central cortical pathways project to ipsilateral spinal accessory nucleus CN XII: Hypoglossal Nerve Functional category Function Somatic motor Intrinsic muscles of the tongue CN XII: Hypoglossal Nerve Somatic motor: intrinsic and extrinsic muscles of the tongue Except muscles for the palatoglossus, innervated by CN X (extrinsic) Upper motor neurons: corticobulbar; lesions primary motor cortex or internal capsule: contralateral tongue weakness Lesion hypoglossal nucleus, fascicles, nerve: ipsilateral tongue weakness Deviation to the weak side by protrusion