神经病学教学ppt课件：General Introduction.ppt

Neurology,General Introduction,The most frequent neurological disorders,Headache (tension type: pop. 40-60%, migraine: femails 9-12%,males 4-6%)Low back painStroke: prev. 2000/100 000Epilepsy: 60-800/100 000Parkinsonism: 300/100 000Polyneuropathy: 300/100 000Multiplex Sclerose:6-80/100 000,General Introduction,Transduction pathway of motor,Contents,Cranial nerves,Transduction pathway of sense,Deep, superficial and pathologic reflexes,1,2,3,4,Status of consciousness,5,Contents,Cranial nerves,1,2,3,4,5,Cranial nerves,Cranial nerves( I ) Olfactory,Major function: smell,Olfactory nerve Cranial nerve I,Close eyeIdentified familiar odors: coffee,cloves andPeppermintNoxious substances not suggested:Ammonia or achol(false positive response),Cranial nerves( II )Optic Nerve,Major function: vision,Optic nerve,Visual acuityWords or letterFingers 1mMovements of handFlash a lightSnellen charts testing20/20 feet and 6/6 meters normal,Normal Fundi,Edema fundi,Visual fields,Cranial nerves( III )Oculomotor(IV) Trochlear (VI)Abducent,Major function:III: eyelid and eyeball movementIV: innervates superior oblique turns eye downward and laterallyVI: turns eye laterally,Example: A complete left III nerve palsy is illustrated along with clinical presentations of left VI and IV nerve palsies.,Pretectum & Pupillary Light Reflex:The pretectum controls the action of the pupillary constrictor muscle via its projection to both Edinger-Westphal nuclei.,Pupillary Constrictor muscle,Pretectum & Pupillary Light Reflex:,The pretectum bilateral projections to the Edinger-Westphalnuclei ensure that both eyes react to light: shining a light into each eye can elicit a direct and a consensual pupillary reflex.This light reflex tells us about ones visual pathways status.,Pretectum & Pupillary Light Reflex:,In summary, pupillary reflexes are clinically important because they indicate the functional state of the afferent and efferent pathways mediating them.The absence of pupillary reflexes in an unconscious patient is a symptom of damage to the pretectum.,Cranial nerves(V) Trigeminal Nerve,Major function:chewing face & mouth touch & pain,Cranial nerves(VII)Facial Nerve,Major function:controls most facial expressions secretion of tears & salivataste,central & peripheral facial paralysis,Paralysis involving all divisions of the nerve is peripheral, and that sparing the forehead is central.,Cranial nerves (VIII) Vestibulocochlear Nerve,Major function:hearing equillibrium sensation,Hearing,Otoscopic inspection of the auditory canals and tympanic membranes,assessment of auditory acuityWeber test (256 Hz tuning fork): unilateral sensorineural hearing loss(from lesion of the cochlea or cochlea nerve). Conductive(external or middle ear),Vestibular portion,Nystagmus Video 1 (wmv 2M).wmv is rhythmic oscillation of the eyes.pendular nystagmus,onset infancy with equal velocity in both direction.jerk nystagmus is characterized by slow phase of movement followed a fast phase in the opposite directionPositional nystagmus test (Dix- HallpikeManeuver for benign positional vertigo,Vertigo and dizzleVertigo is the illusion of movement of the body or the environmentDizzle is sensations of light-headedness,faintness,or giddiness not associated with an illusion of movementRomberg,s sign,Rinne test ACBCACBCBCAC on affected ear,Weber testnormal sound perceived(SP) as coming midlineSensorineural hearing loss SP coming normal ear Conductive hearing loss SP as coming from affected ear,Assessment of hearing loss,AC:air conductionBC:bone conduction,Cranial nerves(IX) Glossopharyngeal Nerve,Major function:taste senses carotid blood pressure,Cranial nerves(X)Vagus Nerve,Major function:senses aortic blood pressure slows heart rate stimulates digestive organstaste,Glossopharyngeal nerve(、）,Sense and motor examinationPharynx(gag) reflex with nause by touching the back of tongue with a tongue bladePharynx (open mouth and say “ah”): uvula rise symmetryLarynx: watch laryngeal contours rise with swallowingSwallow some water(if paralysis induced coughing or reflux into the posterior nose, hoarseness may be unilateral vocal cord paralysis (dysdipsia)Dispnea and inspiratory stridor (bilateral involvement)Disphagia,Cranial nerves(XI) Accessory Nerve,Major function:controls trapezius & sternocleidomastoidcontrols swallowing movements,Accessory nerve,Only motor fiberTwo muscles:trapezum and sternocleidomastoid Palpate the upper borders of the trapeziiLook for scapularSternocleidomastoid (turn head test),Cranial nerves(XII)Hypoglossal Nerve,Major function:controls tongue movements,Hypoglossal nerve,Only motor fiberOboservation the tremors, atrophy and fasciculations(When the tongue protrudes)Deviation toward to paralysis,Paralysis of the hypoglossal nerve affects the tongue. It impairs speech (it sounds thick) and causes the tongue to deviate toward the paralyzed side. In time, the tongue diminishes in size (atrophies).,Hypoglossal tumor,Tongue atrophy in left side,Contents,Cranial nerves,Transduction pathway of sense,1,2,3,4,5,SOMESTHETIC SYSTEM OF THE HEAD,Nerve cells bodies for touch, pressure, pain, and temperature in the head are in the trigeminal (semilunar) ganglion of the trigeminal (CN V) nerve (blue and red lines in figure).Neuronal cell bodies mediating proprioception reside in the mesencephalic nucleus of CNV (purple fibers). Most relay neurons project to the Contralateral VPM nucleus of the thalamus and thence to the postcentral gyrus of the cerebral cortex, where they are somatotopically represented.,RETINOGENICULOSTRIATE VISUAL PATHWAY,The retina has two types of photoreceptors:cones that mediatecolor vision and rods that mediate light perception but with low acuity. The greatest acuity is found in the region of the macula of the retina(where only cones are found (upper left panel).,Visual signals are conveyed by the ganglion cells whose axons course in the optic nerves. Visual signals from the nasal retina cross in the optic chiasm while information from the temporal retina remains in the ipsilateral optic tract. Fibers synapse in the lateral geniculate nucleus (visual field is topographically represented here and inverted), and signals are conveyed to the visual cortex on the medial surface of the occipital lobe.,RETINOGENICULOSTRIATE VISUAL PATHWAY,The positions of injury,The sights,The cochlea transduces sound into electrical signals. This is accomplished by the hair cells, which depolarize in response to vibration of the basilar membrane. The basilar membrane moves inresponse to pressure changes imparted on the oval window of the cochlea in response to vibrations of the tympanic membrane.,AUDITORY PATHWAYS:COCHLEAR RECEPTORS,The cochlea transduces sound into electrical signals. Axons convey these signals to the dorsal and ventral cochlear nuclei, where it is tonotopically organized. Following a series of integrated relay pathways, the ascending pathway projects to the thalamus (medial geniculate bodies) and then the acoustic cortex in the transverse gyrus of the temporal lobe, where information is tonotopically represented (low, middle, and high tones).,VESTIBULOSPINAL TRACTS,VESTIBULAR RECPTORSThe vestibular apparatus detects movement of the head in the form of linear and angular acceleration. This information is important for the control of eye movements so that the retina can be provided with a stable visual image. It is also important for the control of posture.,Sensory input from the vestibular apparatus is used to maintain stability of the head and to maintain balance and posture. Axons convey vestibular information to the vestibular nuclei in the pons, and then secondary axons distribute this information to five sites: spinal cord (muscle control), cerebellum (vermis), reticular formation (vomiting center), extraocular muscles, cortex (conscious perception).,VESTIBULOSPINAL TRACTS,TASTE PATHWAYS,TASTE RECEPTORSTaste buds on the tongue respond to various chemical stimuli. Taste cells, like neurons, normally have a net negative charge internally and are depolarized by stimuli, thus releasing transmitters that depolarize neurons connected to the taste cells.,Depicted here are the afferent pathways leading from the taste receptors to the brainstem and, ultimately, to the sensory cortex in the postcentral gyrus.,TASTE PATHWAYS,OLFACTORY PATHWAY,OLFACTORY RECEPTORS,OLFACTORY PATHWAY,Integrated signals pass along the olfactory tract and centrally diverge to pass to the anterior commissure (some efferent projections course to the contralateral olfactory bulb, blue lines) or terminate in the ipsilateral olfactory trigone (olfactory tubercle). Axons then project to the primary olfactory cortex (piriform cortex), entorhinal cortex, and amygdala.,Olfactory stimuli are detected by the nerve fibers of the olfactory epithelium and conveyed to the olfactory bulb .,SOMESTHETIC SYSTEM OF THE BODY Cutaneous Sensory Receptors:,Cutaneous receptors respond to touch (mechanoreceptors), pain (nociceptors), and temperature (thermoreceptors). Several different types of receptors are present in skin.,SOMESTHETIC SYSTEM OF THE BODY,Pain, temperature, and pressure sensations below the head ultimately are conveyed to the primary somatosensory cortex (postcentral gyrus) by the anterolateral system (spinothalamic and pinoreticular tracts).The fasciculus gracilis and cuneatus of the spinal lemniscal system convey proprioceptive, vibratory, and tactile sensations to the thalamus (ventral posterolateral nucleus).The lateral cervical system mediates some touch, vibratory, and proprioceptive sensations (blue and purple lines show these dual pathways). Ultimately, these fibers ascend as parallel pathways to the thalamus, synapse, And ascend to the cortex.,DERMATOMES,Sensory information below the head is localized to specific areas of the body, which reflect the distribution of peripheral sensory fibers that convey sensations to the spinal cord through the dorsal roots (sensory nerve cell bodies reside in the corresponding dorsal root ganglion). The area of skin subserved by afferent fibers of one dorsal root is called a dermatome. This figure shows the dermatome segments and lists key dermatome levels used by clinicians. Variability and overlap occur, so all dermatome segments are only approximations.,For example, when the C6 nerve is pinched, there is pain and numbness in the thumb and index finger.,List of Dermatomes of Commonly Injured Nerve Roots,C5 The area over the shoulder.C6 The thumb and part of the forearm.C7 The middle finger.C8 The smallest fingers and part of the forearm.L4 The thigh.L5 The medial part of the calf and foot, the big toe.S1 The lateral part of the calf and foot, the smaller toes.,Transduction pathway of motor,Contents,Cranial nerves,Transduction pathway of sense,1,2,3,4,5,Descending Motor Pathways,CORTICOSPINAL TRACTS The corticospinal, or pyramidal, tract is the major motor tract that controls voluntary movement of the skeletal muscles, especially skilled movements of distal muscles of the limbs. All structures from the cerebral cortex to the anterior horn cells in the spinal cord constitute the upper portion of the system (upper motor neuron). The anterior horn cells and their associated axons constitute the lower portion of the system (lower motor neuron).,CEREBRAL CORTEX: LOCALIZATION OF FUNCTION AND ASSOCIATION PATHWAYS,The cerebral cortex is organized into functional regions. In addition to specific areas devoted to sensory and motor functions, there are areas that integrate information from multiple sources.,The corticonuclear tract:,The corticonuclear tract is a white matter pathway connecting the cerebral cortex to the brainstem. The muscles of the face, head and neck are controlled by the corticobulbar system, which terminates on motor neurons within brainstem motor nuclei. The corticonuclear tract runs through the genu of the internal capsule and a few fibers in the posterior limb of the internal capsule, as it passes from the motor cortex down through to the brainstem.,The corticonuclear tract:,The corticonuclear tract innervates cranial motor nuclei bilaterally with the exception of the lower facial nuclei which are innervated only contralaterally (below the eyes) and CN XII, which is innervated contralaterally as well. Among those nuclei that are bilaterally innervated a slightly stronger connection contralaterally than ipsilaterally is observed. The corticobulbar tract directly innervates the nuclei for cranial nerves V, VII, XI, and XII, and indirectly innervates nuclei for nerves III, IV, and VI via interneurons. It also contributes to the motor regions of nerves X and IX in the nucleus ambiguus.,Upper motor neuron paralysis& Lower motor neuron paralysis,These changes in muscle performance vary depending on the site and the extent of the lesion, and may include:* Muscle weakness* Decreased control of active movement* Brisk tendon jerk reflexes* Spasticity: a velocity-dependent change in muscle tone * Clasp-knife response: where initial higher resistance to movement followed by a lesser resistance * Babinski sign is present* increase deep tendon reflex* EMG: nerve conduction was normal and no loss of nerve potentials.,An upper motor neuron lesion is a lesion of the neural pathway above the anterior horn cell or motor nuclei of the cranial nerves.,Upper motor neuron paralysis& Lower motor neuron paralysis,One major characteristic used to identify a lower motor neuron lesion is flaccid paralysis - paralysis accompanied by muscle loss. This is in contrast to a upper motor neuron lesion, which often presents with spastic paralysis - paralysis accompanied by severe hypertonia.* Muscle paresis or paralysis * fibrillations* fasciculations* Hypotonia or atonia* Areflexia or hyporeflexia* EMG: nerve conduction was abnormal and loss of nerve potentials.,A lower motor neuron lesion is a lesion which affects nerve fibers traveling from the anterior horn of the spinal cord to the relevant muscle(s) - the lower motor neuron.,List of Myotomes of Commonly Injured Nerve Roots,C5 The deltoid muscle (abduction of the arm at the shoulder).C6 The biceps (flexion of the arm at the elbow).C7 The triceps (extension of the arm at the elbow).C8 The small muscles of the hand.L4 The quadriceps (extension of the leg at the knee).L5 The tibialis anterior (upward flexion of the foot at the ankle).S1 The gastrocnemius muscle (downward flexion of the foot at the ankle).,Transduction pathway of motor,Contents,Cranial nerves,Transduction pathway of sense,Deep, superficial and pathologic reflexes,1,2,3,4,5,Deep Reflex:,SPINAL REFLEX PATHWAYS,Proprioception and Reflex Pathways,Position sense or proprioception involves input from cutaneousmechanoreceptors, Golgi tendon organs, and muscle spindles(middle figure of upper panel). Both monosynaptic reflex pathways(middle figure of upper panel) and polysynaptic pathways involvingseveral spinal cord segments (top and bottom figures of upperpanel) initiate m