MindMap Gallery Neurology Chapter 1 General Introduction to Neurology 004
Neurology Chapter 1: Neurology General Thought Map, which introduces the localization and diagnosis of nervous system damage, reflexes, brain function localization, etc.
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The ice hockey schedule for the Milano Cortina 2026 Winter Olympics, featuring preliminary rounds, quarterfinals, and medal matches for both men's and women's tournaments from February 5–22. All game times are listed in Eastern Standard Time (EST).
Neurology Chapter 1 General Introduction to Neurology 004
Section 2: Localization and Diagnosis of Nervous System Damage
4. Reflection
Anatomy and Physiology
Deep reflex: The reflex arc is a monosynaptic reflex arc composed of direct connections between sensory neurons and motor neurons; such as jaw reflex (pons), scapular reflex (C5~C6), biceps reflex (C5~C6), Triceps reflex (C6~C8), radial periosteal reflex (C5~C8), knee reflex (L2~L4), Achilles tendon reflex (S1~S2)
Shallow reflex: It is a rapid muscle contraction reaction caused by stimulating the skin, mucous membrane and cornea; the reflex arc can still be transmitted to the cerebral cortex, and then descends to the anterior horn cells of the spinal cord with the pyramidal tract; such as abdominal wall reflex (T7~T12), cremasteric reflex (L1~L2), plantar reflex (S1~S2), anal reflex (S4~S5), corneal reflex (pons), gag reflex (medulla oblongata)
Damage localization
Deep reflexes are weakened/disappeared: injury to any part of the reflex arc path, disconnection shock period of brain/spinal cord injury, mental stress/concentration, sedatives/anesthesia/coma
Deep hyperreflexia: upper motor neuron damage, neurosis, hyperthyroidism, tetanus
Shallow reflexes weaken/disappear: spinal cord reflex arc interruption, pyramidal tract lesions
Pathological reflex: It is a reflex that does not exist under normal circumstances and only appears when the central nervous system is damaged; it is a definite indication of pyramidal tract damage and often coexists with the disappearance of shallow reflexes and hyperreflexia of deep reflexes.
Babinski's sign (Babinski's sign/plantar reflex): the most important pathological reflex; when a needle is passed across the outer edge of the sole of the foot from back to front, the big toe dorsiflexes and the remaining four toes fan out (positive); However, normal babies under 1 year old can also be positive
Hoffmann's sign (Hoffmann's sign): Hold the patient's wrist with your left hand, pinch the patient's middle finger with the index finger and middle finger of your right hand, and flick the nail of the patient's middle finger downward with your thumb. When the thumb and other fingers are palmarly flexed (positive)
Mass reflex/withdrawal reflex/defense reflex: seen in complete transverse spinal cord injury (disconnected from the brain); manifested by stimulation of any part of the lower limbs, positive bilateral Babinski sign and bilateral lower limb gyrus. Contraction (hip flexion, knee flexion, ankle dorsiflexion), even subtle stimuli that are not easy to detect can cause this reflex (it seems to happen automatically); severe flexor spasm can eventually form a persistent flexion posture of the lower limbs (flexion paraplegia); When the reaction becomes more intense, it may be accompanied by emptying of urine and feces, sweating/piloerection/skin redness below the level of the lesion.
Oral reflex: Note that this reflex is normal in newborns and young children.
Lip reflex/sucking reflex: When lightly scratching the lips/tapping the corner of the mouth, the upper and lower lips protrude to make a sucking action; this is a sign of the release of the pyramidal tract in the brain innervation area (pseudobulbar palsy)
Palmomental reflex: lightly scratching the skin on the thenar surface of the palm can cause contraction of the mental muscle on the same side; the reflex will be hyperactive when the cortical brainstem tract above the pons is damaged.
strong grip reflex
5. Brain Function Positioning
(1) Cerebral hemisphere
Classification
Dominant hemisphere: The hemisphere that is dominant in language, logical thinking, analysis and synthesis, and calculation functions; mostly located on the left side (only some right-handers and about half of left-handers may be on the right side)
Non-dominant hemisphere: dominant in music, art, comprehensive ability, space, geometric figures, recognition of faces and visual memory functions, etc.
Partition
frontal lobe
Functional partition
Cortical motor area (precentral gyrus): forms most of the pyramidal tract; controls voluntary movement of the contralateral half of the body ("inverted human shape")
Premotor area (in front of the precentral gyrus): Extrapyramidal cortical center; related to joint movement, postural adjustment, co-motor movement, autonomic nervous function, and muscle tone inhibition
Cortical lateral vision center/eye gaze center (posterior middle frontal gyrus): controls the same direction (contralateral) lateral gaze movement of both eyes
Writing center (posterior middle frontal gyrus of dominant hemisphere): adjacent to the cortical motor area that controls the hand
Motor speech center/Broca’s area (upper Sylvian fissure and posterior inferior frontal gyrus): controls speech movement
Prefrontal lobe: extensive contact fibers; related to memory, judgment, abstract thinking, emotion, and impulsive behavior
Lesion manifestations and localization diagnosis
Lateral surface: seen in cerebral infarction, tumors, and trauma
Frontal pole: mental disorders (memory/attention loss, slow reaction, etc.)
Precentral gyrus: epilepsy (irritating lesions), paralysis (destructive lesions)
Posterior superior frontal gyrus: contralateral upper limb grasping reflex (grasp reflex) ①, groping reflex (groping reflex) ②
① It refers to the phenomenon that when an object touches the palm of the patient's contralateral side to the lesion, it causes a flexion reaction of the fingers and palm, causing the patient to hold the object tightly and not let go.
② Refers to the phenomenon that when the palm on the opposite side of the lesion touches an object, the limb gropes in all directions until it grasps the object and holds it tightly.
Posterior part of the middle frontal gyrus: both eyes gaze to the contralateral side of the lesion (irritating lesions)/ipsilateral gaze (destructive lesions), and inability to write
(Dominant hemisphere) Posterior inferior frontal gyrus: motor aphasia
Medially: seen in anterior cerebral artery occlusion and parasagittal sinus meningiomas; posterior paracentral lobular lesions can cause paralysis of the contralateral side below the knee (compared to spinal cord lesions, there is no paralysis above the knee)
Bottom surface: seen in contusion, olfactory groove meningioma, sphenoid crest meningioma
Frontal orbital surface (limbic system damage): Overeating, excessive gastrointestinal motility, polyuria, high fever, sweating, skin vasodilation
Foster-Kennedy syndrome: Tumors near the olfactory groove on the base of the frontal lobe may cause anosmia on the ipsilateral side, pallor and atrophy of the ipsilateral optic papilla, and papilledema on the contralateral side.
parietal lobe
Functional partition
Cortical sensory area (postcentral gyrus): receives the deep and shallow sensations of the contralateral limb ("inverted human shape"); the parietal lobule is the cortical center for touch and entity sensation
Application center (dominant supramarginal gyrus): related to complex movements and labor skills
Visual language center/reading center (angular gyrus)
Lession manifestations and localization diagnosis
Postcentral gyrus and superior parietal lobule
Destructive lesions: Complex sensory impairment of the contralateral limb
Irritant lesions: Partial sensory epilepsy of the contralateral limb
Infraparietal lobule (supramarginal and angular gyrus)
Body image disorder
Gerstmann syndrome: caused by damage to the angular gyrus of the dominant hemisphere; manifested by acalculia, finger agnosia, left-right agnosia, agraphia, and may be accompanied by alexia
Apraxia: caused by damage to the supramarginal gyrus of the dominant hemisphere
Temporal lobe
Functional partition
Sensory speech center/Wernicke’s area: angular gyrus and posterior superior temporal gyrus
Auditory center: middle part of superior temporal gyrus, transverse temporal gyrus
Olfactory center: uncus and anterior part of hippocampus
Anterior temporal lobe: related to high-level neural activities such as memory, association, comparison, etc.
Mesial surface of temporal lobe: belongs to limbic system, including hippocampus
Lession manifestations and localization diagnosis
Lesions in the posterior superior temporal gyrus of the dominant hemisphere: sensory aphasia
Lesions in the posterior middle temporal gyrus of the dominant hemisphere: naming aphasia
Uncinus lesions: phantom smells, phantom tastes, tongue licking, chewing movements (uncus seizures)
Hippocampal lesions: epilepsy, delusions, hallucinations, automatisms, déjà vu, emotional abnormalities, psychosis, visceral symptoms/convulsions, severe recent memory impairment
Extensive damage to the temporal lobe of the dominant hemisphere/bilateral temporal lobe damage: psychiatric symptoms (personality changes, abnormal mood, memory impairment, mental retardation, indifferent expression)
Deep optic radiation fiber/optic tract damage in the temporal lobe: homonymous hemianopia in the contralateral visual fields of both eyes
Occipital lobe
Functional division - visual center/striatal area (surrounding the calcarine cortex): receives visual impulses from the lateral geniculate body, "up to up, down to down"
Lession manifestations and localization diagnosis
Visual center
Irritating lesions: visual hallucinations
Destructive lesions: visual field defect; ① bilateral visual center lesions → complete cortical blindness (total blindness, but light reflection exists); ② visual center lesions on one side → homonymous hemianopia in the contralateral visual field, no impact on central vision (macular Avoidance (macular sparing); ③ Glossary gyrus lesions below the calcarine fissure → Homotropic upper quadrantopia in the contralateral visual field; ④ Cuneiform gyrus lesions above the calcarine fissure → Homotropic lower quadrantanopia in the contralateral visual field
Macular avoidance: Possible reasons: ① Some visual fibers in the macular area have bilateral projections; ② The visual cortex that receives the projection of macular fibers has dual blood supply from the anterior and posterior circulation of the brain.
Lesions around the visual center of the dominant hemisphere: visual agnosia (not blind, but losing the ability to distinguish shapes, faces, and colors, and sometimes requiring the help of touch to identify)
Parieto-occipital junction area lesions: visual distortion (sometimes a precursor to epilepsy)
Insula/insula: deep surface of Sylvian fissure, related to visceral sensation and movement
Limbic lobe: an arc-shaped structure located around the corpus callosum and the lower wall of the lateral ventricle on the medial side of the hemisphere; including the septal area, cingulate gyrus, hippocampus, parahippocampal gyrus, and uncus; and the amygdala, anterior nucleus of the thalamus, and inferior The thalamus, midbrain tegmentum, anterior insula, frontal orbital surface and other structures together form the limbic system, which participates in high-level neurological, mental and visceral activities.
(2) Internal capsule
Anatomy and Physiology
Location: Laterally, it is the lentiform nucleus, medially, it is the thalamus, and it is the caudate nucleus anteromedially.
Divisions: Forelimbs (anterior thalamic radiation, frontopontine tract), knees (cortical brainstem tract), hind limbs (corticospinal tract, central thalamic radiation, auditory radiation, temporopontine tract, posterior thalamic radiation, optic radiation)
Lesion location
Complete internal capsule damage: "tri-hemian" syndrome (contralateral hemiplegia, contralateral hemiplegia, contralateral hemianopia)
partial internal capsule damage
(3) Basal ganglia/basal ganglia (see above)
(4) Diencephalon
Features
Including thalamus, epithalamus, hypothalamus, and subthalamus; most lesions have no obvious localization signs; space-occupying lesions in this area are similar to intraventricular tumors (called "midline tumors")
thalamus
Anatomy and Physiology
Pronucleus group: limbic system relay station; related to visceral activity
Medial nucleus group: including dorsomedial nucleus and ventromedial nucleus; it is the integration center of somatic/visceral sensation
Lateral nucleus group
Ventral nucleus group: ventroanterior nucleus → regulates body movement; ventrolateral nucleus → regulates extrapyramidal motor coordination; ventroposterolateral nucleus → spinothalamic tract & medial lemniscus (body/limb sensation); ventroposteromedial nucleus → Trigeminal system (facial sense of taste); medial geniculate body → hearing; lateral geniculate body → vision
Dorsal nucleus group
Lesion localization—taking lateral core group lesions as an example
Lesions of the ventroposterolateral nucleus and ventroposteromedial nucleus: contralateral hemiplegia sensory impairment (characteristics: ① All senses are impaired; ② Deep sensory/fine touch impairment is more severe than shallow sensory impairment; ③ Limb/trunk sensory impairment is more severe than the face; ④ There may be ataxia caused by deep sensory impairment; ⑤ abnormal sensation; ⑥ spontaneous pain on the contralateral side of the body (thalamic pain))
Thalamus pain: ①Characteristics: The pain location is diffuse and not fixed, the nature of the pain is difficult to describe, the pain can be aggravated by various emotional stimuli, and is often accompanied by autonomic nervous system dysfunction (such as increased blood pressure and blood sugar)
And red nucleus/cerebellum/globus pallidus contact fiber lesions: contralateral hemisphere involuntary movements
epithalamus
Anatomy and physiology: pineal gland, habenular commissure, posterior commissure
Lesions: Parinaud syndrome may occur with pineal gland tumors
hypothalamus
Anatomy and physiology: preoptic area (temperature regulation), supraoptic area (supraoptic nucleus, paraventricular nucleus), tubercular area (ventromedial nucleus, dorsomedial nucleus, infundibulum nucleus), mammillary body area (posterior hypothalamic nucleus, mammillary body nucleus)
Lesion location
Supraoptic nucleus and paraventricular nucleus lesions: central diabetes insipidus
Lesions of the thermoregulatory center: lesions in the anteromedial zone → heat dissipation disorder; lesions in the posterolateral zone → heat production disorder
Lesions of the satiety center (ventromedial hypothalamus nucleus) and food intake center (ventrolateral hypothalamus nucleus)
subthalamus
Anatomy and Physiology: Subthalamic nucleus (extrapyramidal system)
Impairment: Off-body throwing motion
(5) Brainstem
Anatomy and Physiology
Nerve nuclei: midbrain (pairs of cranial nerves III and IV); pons (pairs of cranial nerves V, VI, VIII, and VIII); medulla oblongata (pairs of cranial nerves IX, X, XI, and XII); nucleus fasciculata, cuneus Fascicular nucleus; red nucleus, substantia nigra
conductive bundle
Reticular structure: multiple neuromodulatory centers, ascending reticular agonist system
Lesion location
Medulla oblongata
Lesions of the dorsolateral region of the upper medulla oblongata - dorsolateral medulla syndrome/Wallenberg syndrome
Manifestations: ① Dizziness, nausea, vomiting, nystagmus → damage to the vestibular nerve nucleus; ② Paralysis of the soft palate/pharyngeal muscles on the affected side (dysphagia, dysphonia, drooping of the ipsilateral soft palate, loss of gag reflex) → nucleus ambiguus/glossopharyngeal nerve /Vagus nerve damage; ③ Ataxia on the affected side → Damage to the funicular body/spinocerebellar tract/part of the cerebellar hemisphere; ④ Horner syndrome on the affected side → Damage to the descending sympathetic fibers; ⑤ Crossed sensory disorder (loss of pain and temperature sensation on the same side of the face , loss of pain and temperature sensation on the contralateral hemisphere) → damage to the spinal nucleus of the trigeminal nerve and damage to the lateral spinothalamic tract
Seen in: obstruction of posterior inferior cerebellar artery, vertebrobasilar artery, lateral medullary artery
Mesioventral lesions of the medulla oblongata - medial bulbar syndrome/Dejerine syndrome
Manifestations: ① Paralysis and atrophy of the tongue muscle on the affected side → hypoglossal nerve damage; ② Central paralysis of the upper and lower limbs on the contralateral side → damage to the pyramidal tract; ③ Hyposensation/loss of deep sensation on the contralateral side → damage to the medial lemniscus
Seen in: vertebral artery and its branches, basilar artery posterior vascular obstruction in the pons
Lesions of the ventrolateral pons - ventrolateral pons syndrome/Millard-Gubler syndrome
Manifestations: ① Inability to abduct the eyeball on the affected side, peripheral facial paralysis → abducens nerve palsy, damage to the facial nerve nucleus; ② Central hemiplegia on the contralateral side → damage to the pyramidal tract; ③ Sensory disorder on the contralateral side → medial lemniscus, spinothalamic tract damage
Seen in: obstruction of the inferior anterior cerebellar artery
Lesions of the ventromedial part of the pons - ventromedial pons syndrome/Foville syndrome
Manifestations: ① Inability to abduct the eyeball on the affected side, peripheral facial paralysis → abducens nerve palsy, and damage to the facial nerve nucleus; ② Both eyes gaze to the opposite side → damage to the lateral visual center and medial longitudinal fasciculus of the pons; ③ Central hemiplegia on the contralateral side → pyramidal beam damage
Seen in: paramedian pontine artery occlusion
Dorsolateral pontine lesions - pontine tegmentum syndrome/superior cerebellar artery syndrome/Raymond-Cestan syndrome
Manifestations: ① Dizziness, nausea, vomiting, nystagmus → damage to the vestibular nerve nucleus; ② Inability to abduct the eyeball on the affected side → abducens nerve paralysis; ③ Paralysis of the affected side → damage to the facial nerve nucleus; ④ Horner syndrome on the affected side → descending sympathetic fibers Damage; ⑤ Ipsilateral hemitaxia → damage to the middle cerebellar peduncle, inferior cerebellar peduncle and spinocerebellar anterior bundle; ⑥ Crossed sensory disorder; ⑦ Gaze to the opposite side → damage to the pontine lateral visual center and medial longitudinal fasciculus; ⑧ Right Hypoesthesia/loss of deep body hemisphere→medial lemniscus damage
Seen in: superior cerebellar artery/inferior anterior artery obstruction
Bilateral pontine base lesions - locked-in syndrome/deefferented state
Manifestations: clear consciousness, no obstacle in language understanding, bilateral central paralysis, only able to move the eyes up and down, horizontal eye movement disorder, unable to speak, bilateral facial paralysis, tongue, pharynx, articulation, and swallowing movement disorders, unable to turn Neck shrug, may have bilateral pathological reflexes, often mistaken for coma (but EEG is normal)
Seen in: Bilateral occlusion of the pontine branches of the basilar artery → Bilateral corticospinal tracts and cortical brainstem tracts innervating the trigeminal nerve are affected
midbrain
Damage to the sole of the cerebral peduncle on one side of the midbrain—cerebral peduncle syndrome/ventral midbrain syndrome/Weber syndrome
Manifestations: ① Paralysis of all ophthalmic muscles except the rectus and superior oblique muscles on the affected side, mydriasis → oculomotor nerve palsy; ② Central facial and tongue paralysis on the contralateral side, paralysis of the upper and lower limbs → pyramidal tract damage
Seen in: Tentorial hiatal hernia
Mesencephalic quadrigeminal damage - mesencephalic tectum syndrome/quadrigeminal syndrome/Parinaud syndrome
Manifestations: ① Loss of pupillary light reflex (superior colliculus); ② Vertical eye movement disorder (especially upward gaze) (superior colliculus); ③ Nervous deafness (inferior colliculus); ④ Cerebellar ataxia (combined brachial ataxia) )
Seen when tumors (such as pineal tumors) compress the midbrain quadrigemium (ie, tectum)
Diffuse damage to the bilateral brainstem: may manifest as lethargy and coma (high brainstem tumor), central hyperventilation (damage to the midbrain and lower pontine tegmentum), long-breathing (damage to the lateral part of the middle pontine tegmentum) ), ataxic breathing/Biot breathing (bulbar damage)