USMLE Step 1 Sample.pdf - Index 1 Anatomy 2 2 Physiology 34...

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S.S.Patel , M.D.© All rights reserved1Index1Anatomy22Physiology343Biochemistry694Cell Biology855Genetics946Microbiology987Immunology1328Biostatistics1449Behavior Science14610Pharmacology15511Pathology19012Buzzwords for USMLE242
S.S.Patel , M.D.© All rights reserved2Anatomy - Brain§Forebrain– Telencephalon [Cerebral cortex, basal ganglia, Lateral ventricles &Olfactory bulb] & Diencephalon [prethalamus, thalamus, hypothalamus, subthalamus,epithalamus, pretectum and the posterior pituitary gland]§Midbrain– Mesencephalon [Midbrain, Cerebral aqueduct]§Hindbrain– Metencephalon [Pons & Cerebellum] & Myelencephalon [Medulla] [4thventricle forms from both metencephalon & myelencephalon]§Anterior Pituitary gland– is an outgrowth of oralectoderm[Rathke’s pouch].Remnant of Rathke’s pouch formsCraniopharyngiomathat compress Optic chiasm andproduce bitemporal heteronymous hemianopsia§Neural Crest form– Adrenal medulla, Primary sensory neurons & Post-ganglionicautonomic neurons [Cell bodies in ganglia (Peripheral Nervous System (PNS)]§Neural tube form– skeletal motor neurons & Pre-ganglionic autonomic neurons [Cellbodies in SC (Central nervous system (CNS)]§Schwann cells make myelin for PNS§Oligodendrocytes make myelin for CNSBasic Concepts§Our cerebral cortex has an ultimate control on over body!§Our body send sensation to our cortex so sensory fibers are always afferent(goes toward brain)§Our cortex send information to different part of body to do their function somotor fibers are always efferent (goes away from brain)§No matter which fibers [afferent or efferent], both cross midline so our braincontrol opposite side of our body! Right side of brain control left side of body!So any lesion to our brain produce Contralateral (opposite side) defect.Exception to this rule is cerebellum. Cerebellar fibers cross midline twice socerebellar lesion produce Ipsilateral (same side) defect.§For Cranial Nerves (CN), most of the CN nuclei are located in brain stem sothese nuclei work as LMN for those CN and their control (cerebral cortex)work as UMN for them.§UMN lesion – spastic paralysis, usually contralateral§LMN lesion – flaccid paralysis, usually ipsilateral§As I mentioned above cerebral cortex control opposite side of our body,involvement of CN in cerebral cortex lesion is contralateral and ipsilateral inbrainstem lesion.§Important parts of our brain – Cerebral cortex, Brain stem (Mid brain, Ponsand Medulla) and Cerebellum. Other small parts are Basal ganglia, Thalamus,Hypothalamus, and Internal Capsule. Spinal Cord is also a part of CNS!
S.S.Patel , M.D.© All rights reserved3§Optic N (CN-2) is an outgrowth of brain so its myelin is formed by oligodendrocytes.CN-2 is affected in Multiple Sclerosis§Sympathetic Outflow– T1 to L2 [Descending hypothalamic fibers drive all Pre-ganglionic sympathetic nerve fibers]§Parasympathetic OutflowCN-3,7,9,10and S-2,3,4§Optic canal – CN-2 (optic N) & ophthalmic artery§Rotundum – Maxillary N (CN-5 second division) (V2)§

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Term
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Tags
Immunology, Pathology, Usmle, cerebral cortex lesion, unilateral lesion

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