CN 2 3 4 6 modalities Sensory: SSA (Vision) course Rods and cones of the retina bipolar neurons gangli on cells Optic nerve optic foramen Optic chiasm Optic tracts Sup colliculi LGN Optic radiation cortex Mixed: GSE (extraocular muscles), GVE (parasympathetic for the intrinsic muscles), proprioceptive Midbrain (anteriorly) Cavernous sinus Superior and inferior branches Superior orbital fissure innervate all eye muscles except lateral rectus & sup oblique in midbrain in level of sup colliculi Main motor (GSE): anterior to cerebral aqueduct, connect with: sup colliculi ipsilateral & cortex bilateral Accessory parasympathetic (Edinger Westphal )(GVE): post to somatic motor, Connect with Pretectal (light reflex) Mixed: GSE, proprioceptive Midbrain lateral wall of Cavernous sinus Superior orbital fissure Innervate the sup oblique Primary motor (GSE): in midbrain in level of inf colliculi, Connect to Cortex (bilaterally) & superior colliculus. Fibers course: Crossing over posteriorly in sup medullary vellum Mixed: GSE, proprioceptive Pons (anteriorly)-btw pons & medulla sulcus lateral wall of Cavernous sinus Superior orbital fissure innervate lateral rectus (abductor) Primary motor (GSE): near midline + 4th ventricle + rhomboid fossa ( facial colliculus) at the same level of facial colliculus connect with: Cortex (bilaterally)&sup colliculus (most ipsilateral) branches superior branch Superior rectus and levator palpebrae superioris inferior branch Medial rectus, inferior rectus, and inferior oblique Parasympathetic innervation (ciliary ganglion) intrinsic eye muscles
functions vision -movements of upper eyelid and eyeball -Adjustment of lens for near vision -constriction of pupil lesions notes -in optic nerve: monocular blindness -In chiasm: bitemporal heminopia -in tract: homonymous heminopia -Eye oriented laterally+ inferiorly diplopia -dilation of pupil -Ptosis -the reflex to other eye continue Testing: Asked to move the eye -Unable to move up, down, or medial -At rest looks down & lateral Movement of sup oblique eye oriented to sup medial diplopia Smallest cranial nerve, Only one to arise from the posterior aspect of the brain stem Decussate and rotate around the brainstem abduction of the eyeball (so called abducent) Eye oriented medially (diplopia, internal strabismus) can t move the eye latterly
CN 7 8 12 modalities Mixed: Motor (SVE): from the pons and innervate facial, scalp muscles Parasympathetic (GVE): pterygopalatine and submandibular ganglia glands SVA: taste buds of the anterior 2/3 of the tongue GVA: soft Palate GSA: external ear course Pons (cerebellopontine angle) Internal acuastic meatus Facial canal Stylomastoid foramen main motor (SVE): deep in the reticular formation in the lower part of the pons, connects with the cortex, innervates the upper muscles of facial expression bilaterally and the lower muscles contralateral, Fibers go posteriorly looping around abducent Parasympathetic nuclei (GVE): Superior salivatory & Lacrimal nuclei which connect with hypothalamus, Lacrimal also connects with Sensory nuclei of Trigeminal (corneal irritation felt by trigeminal lacrimation by facial) Sensory : 1st order neuron geniculate ganglion 2nd order neuron Nucleus of the tractus solitarius (SVA, GVA) Mainly a sensory nerve but cochlear has an efferent for ulduar hair cells Between pons & medulla Internal acoustic meatus inner ear Auditory Nuclei: Receptors in the spiral organ in the cochlea 1st order neuron spiral ganglion 2nd order neurons Anterior & posterior nuclei, Axons cross and uncross midline 3rd order neurons Posterior of trapezoid body & superior olivary, Axons lateral lemniscus 4th order neurons Inferior colliculus Medial geniculate body (5th) internal capsule auditory cortex (superior temporal gyrus) The Vestibular Nuclei: 4th ventricle Receptors in the semicircular canals; saccule, and utricle 1st order neuron vestibular ganglion 2nd order neurons have 4 nuclei that connects mainly with cerebellum and the lateral connects with spinal cord (Lateral vistibulospinal tract, Superior, Medial, Inferior) Inputs from cerebellum Mixed, primarily motor (GSE): innervate the all tongue muscles (intrinsic + extrinsic) Exiting from the pre-olivary sulcus hypoglossal canal cervical region floor of the mouth just above the mylohyoid m. GSE: located in medulla oblongata (in most medial dorsal part ) reflection hypoglossal trigon on the floor of the rhomboid fossa connect to cortex (bilaterally)
3rd order neuron PVM of thalamus Then to postcentral gyrus via internal capsule Axons To spinal cord, To eye muscles nerves (III, IV, VI), To thalamus (VP) vestibular area in cerebral cortex (postcentral gyrus) branches functions lesions notes 1-Nerve to stapidius muscle (SVE): facial canal stapidius muscle in the middle ear 2- Posterior auricular n. (SVE): innervates Stylohyoid muscles & posterior belly of digastric muscle 3-5 terminal branches (SVE): temporal, zygomatic, buccal, marginal mandibular, cervical 4- Greater petrosal nerve (GVE,GVA): parasympathetic lacrimal and small salivary glands 5-Chorda tympani n. (GVE submandibular & sublingual glands),(sva ant. 2/3 of the tongue\taste),(gva) regulating muscles of facial expression and secretion of saliva and tears Facial palsy (Bell s palsy): Unable to show teeth and close eye Loss of corneal reflex Loss of taste from the anterior ⅔ of tongue defect in salivation, lacrimation, hearing Don t innervate the parotid gland although it pierces it Cochlear branch: hearing Vestibular branch: equilibrium Hearing & equilibrium deafness or tinnitus disequilibrium, vertigo, nystagmus, ataxia Controls muscles of tongue during speech and swallowing Atrophy in tongue m. Injury deviates tongue to injured side when protruded
CN 9 10 11 modalities Mixed SVE: stylopharyngeus muscle GVE: Parasympathetic via otic ganglion parotid gland (regulation of secretion of saliva) GSA superior ganglion external ear GVA inferior ganglion The pharynx & posterior ⅓ of tongue, Carotid sinus baroreceptors, Carotid body chemoreceptors SVA inferior ganglion Taste buds of the posterior third of the tongue (taste) course medulla (between olive & inferior cerebellar peduncle) Jugular foramen give superior ganglion and inferior ganglion: the superior one responsible for GSA,, and inferior one give GVE and SVA Main motor (SVE): ( ambiguus) in medulla, connect to cortex bilaterally Parasympathetic (GVE): (inferior salivatory ), Mixed SVE: Muscles in the respiratory passageways (skeletal muscle for pharynx and larynx) GVE: smooth muscle of Lungs, heart, esophagus, stomach, small intestine, most of the large intestine and the gallbladder & GIT glands GVA: sensory receptors from abdomen,thorax,up to the laryngopharynx (inferior nodose ganglion) GSA: The ear small part from external auditory canal (superior jagular ganglion) SVA: Some taste buds on epiglottis (inferior nodose ganglion) exiting from post-olivary sulcus jugular foramen giving superior and inferior ganglion reach below the mandible pass through the carotid sheath thorax & abdomen (only cranial nerve reach them) Main motor SVE: Nucleus Ambiguous: vagus part for all pharyngeal muscles & laryngeal muscles with some exceptions (stylopharyngeus Muscle by CN9) Mixed: primarily motor (SVE) Cranial root: originates from post-olivary sulcus join vagus Spinal root (SVE): originates in the anterior gray horn of the first five segments of the cervical spinal cord foramen Magnum jugular foramen Cranial root (SVE): Nucleus ambiguous Join vagus outside the skull Spinal root (SVE):
branches posterior to ambiguous, Connect to hypothalamus Sensory (SVA, GVA): ( of the tractus solitarius) Tympanic n tympanic plexus (tympanic cavity) lesser petrosal n fissure between petrous portion & greater wing of sphenoid otic ganglion posterior to parotid gland Carotid sinus n. Nerve to stylopharyngeus m Pharyngeal branches pharyngeal plexus Lingual branch Parasympathetic (dorsal of the vagus) (GVE): (in medulla ) lateral to hypoglossal posteriorly located has tripod in rhomboid fossa, Connect to hypothalamus Sensory ( of the tractus solitarius)(sva, GVA) Meningeal branch (dura matter above tentorium cerebelli) Auricular branch (external auditory canal) Pharyngeal branches pharyngeal plexus Superior laryngeal n. (mixed) Inferior laryngeal n. Internal laryngeal n. (sensation for larynx above vocal cord) External laryngeal n. (motor for cricothyroid muscles ) Left & right Recurrent laryngeal n.( motor for all laryngeal m. +sensation in lower part) Cardiac branches cardiac plexus pulmonary branches Spinal FROM (anterior horn C1 C5) Connect to cortex bilaterally Fibers course: From SC between the roots of spinal nerves functions Mentioned above Cranial root: Innervates the skeletal muscles of the pharynx, larynx, and soft palate that are used in swallowing Spinal root SVE: Innervates the sternocleidomastoid and trapezius muscles to coordinate head lesions Loss of gag reflex (afferent limb) & Hypersensitive carotid sinus reflex (syncope) & Loss of general sensation in the oropharynx & Loss of taste from posterior ⅓ if the tongue & Glossopharyngeal neuralgia (irritation of the nerve pain in the back of the throat, tongue and ear) block for all visceral organs & Ipsilateral paralysis of the soft palate, pharynx, larynx mm & dysphonia, dyspnea, dysarthria & dysphagia & Loss of gag reflex (efferent limb) & Anesthesia of pharynx & larynx movements IN Spinal root: Difficult moving the head & Shoulder droop
modalities course branches ophthalmic maxillary mandibular GSA innervate sup 1/3 of GSA supply middle third of the GSA supply lower third of face + scalp + orbit head the head SVE masticatory muscle enter from Superior orbital from foramen rotundum-open infra temporal fossa fissure -Frontal nerve (Supraorbital scalp Supratrochlear skin of the eyelid) -Lacrimal nerve Lacrimal gland (receive Zygomatic branch of maxillary nerve which Carry parasympathetic fibers) -Nasociliary nerve Anterior & posterior ethmoidal n for paranasal sinuses, Infratrochlear n, Long ciliary nn. (Carry sympathetic fibers (dilator pupillae m.)(gsa), Communicating branch to ciliary ganglion sensory fibers (GSA) from short ciliary nn for posterior part of eyeball in ptyregopaltine fossa -Meningeal branches -Zygomatic branch: face above zygomatic bone, carry postganglionic fiber to lacrimal nerve, inferior orbital fissure two branches: Zygomaticotemporal & Zygomaticofacial -Posterior superior alveolar n: posterior third of the upper jaw -Infraorbital nerve: inferior orbital fissure to infra orbital groove infraorbital foramen to area above maxilla two branches: Middle & anterior superior alveolar -Ganglionic branches (pterygopalatine nerves):postganglionic neurons towered nasal cavity and palate Greater &lesser palatine, Nasal branches (posterior superior lateral, posterior superior medial, & nasopalatine), Pharyngeal branch foramen ovale -Meningeal branch: foramen spinosum -Nerve to medial pterygoid: branches to tensor tympani, tensor palatine, medial pterygoid muscle -Anterior division: Masseteric n. (masseter muscle), Deep temporal nn. (temporal),nerve to lateral pterygoid, Buccal nerve (GSA to Cheek region) - Posterior division: Auriculotemporal n. (upper part of the mandible), Lingual n (GSA to tongue), Inferior alveolar n (lower jaw), Mylohyoid n. (GSE), Mental n. from mental foramen
course lesions test Trigeminal nerve Emerges from two roots on the ventrolateral surface of pons laterally and the Cell body of it in the trigeminal ganglion which is found in the middle cranial fossa Motor (SVE): superior to abducent &facial in pons, connect to Cortex bilaterally & to Reticular formation, red, tectum *The small motor root (SVE) originates from the pons pass beneath the ganglion Join the mandibular branch for mastication Sensory Nuclei (GSA): 1st order neurons: in the Trigeminal ganglion (exception: proprioception information have first order neuron in the mesencephalic ) 2nd order neurons: Trigeminal nerve sensory nuclei Central axons cross midline Form trigeminal lemniscus 3rd order neurons :VPM of thalamus Internal capsule *The large sensory root (GSA) trigeminal ganglion in the trigeminal cave of the dura matter -Loss of general sensation in anterior two third of head (hemianesthesia) from face and oral (soft palate so may affect swallowing ) & nasal cavities -Loss of corneal reflex (V1) afferent limb -Paralysis of the muscles of mastication -Deviation of the mandible to the weak side -Paralysis of the tensor tympani muscle partial deafness -Trigeminal neuralgia Sensory by touching face using cotton ball Motor by assisting masticatory muscles (masseter & temporalis) on clenching