Ch. 1 Notes Neuroanatomy of the Brain PDF

1.1 Neuroanatomy of the Brain ' Nervous System • peripheral nervous system central brain: brainstem, cerebellum efferent: nerve signals away from cerebrum, • connect spinal cord to spinal CNS to periphery periphery (limbs, core, cord nerve endings) afferent: signals towards CNS for appr...

1.1 Neuroanatomy of the Brain ' Nervous System • peripheral nervous system central brain: brainstem, cerebellum efferent: nerve signals away from cerebrum, • connect spinal cord to spinal CNS to periphery periphery (limbs, core, cord nerve endings) afferent: signals towards CNS for appropriate response Cerebrum :conscious thought & higher order thinking cerebral hemispheres • • diencephalon: central core of gyri, sulci, folds, grooves internal capsule: info b/w cerebral cortex & subcortical • structures (separates lenticular nucleus from thalamus) brain thalamus, basal ganglia, hypothalamus, subthalamus, (putamen & globus pallidus) epithalamus (all gray matter) brain: director • cerebrum, cerebellum, & brainstem • relay center for sensory & motor input • link to endocrine system w/ pituitary gland & circadian rhythm brain components . brainstem:midbrain, pons, medulla practice: know all label of brain gray matter: includes basal ganglia (lenticular nucleus), amygdala, hippoxampus : deep to cerebral cortex (neural integration & processing) • temporal lobe: auditory processing, language, memories • frontal lobe: primary motor cortex • parietal lobe: primary sensory cortex • occipital lobe: primary visual cortex cerebellum: • coordinate movement,, integrate sensory info to guide body response two lateral hemispheres connected by vermis three lobes : ant, post, flocculonodular brainstem: convey/process signals b/w body and cerebrum (regulate subconscious functions, HR, breathing) Extra CN CN 6-8 b/w medulla oblongata and pons Refer to mnemonics page • made up of: midbrain, pons, medulla oblangata • I • most rostral • ant part of cranial fossa • CN 3-4 • CN 5 most caudal & continuous with spinal cord • CN 9-12 1.2 Neuroanatomy of the Support System know flow of csf in ventricles & meninges Locations forms cerebral spinal fluid (CSF) Gray on outside—white inside • 50/50 ventricles! • lat ventricle->iv physical support of brain, foramen-> 3rd vent -> absorb shock, keep neurons in White outside—gray inside cerebral aqueduct -> homeostasis, provides 4th ventricle at pons/ nutrition/immune cells medulla level -> central canal of sc 4 ventricles 3rd ventricle lateral ventricles • largest • drain through IV • 4th ventricle • foramen into aqueduct, into 4th ventricle drains into central canal @ pons & medulla of spinal cord central 3rd canal in drains from cerebral diencephalon brain arterial supply • 2 internal carotid arteries • 2 vertebral arteries: cervical & atlantic dural / venous sinus : valveless veins receives 1/6th CO • consumes 1/5 O2 drain deox blood from brain to internal jug veins spinal cord major reflex center& conduction pathway for efferent & afferent * does not always match vertebral column conus medullaris: (L1-L2) where spinal cord tapers off cauda equina: loose spinal nerve roots, originate from lumbosacral enlargement & conus medullaris (part of PNS) fílum termínale: longest part of cauda equina • anchors coccyx to spinal cord STABILITY white matter surrounds periphery gray matter centralized here cell bodies • forms ant/post horns send out motor signals to periphery except dorsal roots • • nerve tract w/ info receive sensory info from periphery via posterior sensory route lateral horn enlargements @ cervical & lumbar • lumbar plexus t11-s1 • brachial plexus c4-t1 myelinated fibers forming • • comes off ventral horn vital for sympathetic division of ANS 1.3 Development of the Nervous System 1 Development of the Nervous System pre-embryonic (conception - day 14) fertilization of ovum (single cell) in uterine tube divides as moving down uterine tube arrives at uterus: divides into 4 continuous dividing until solid sphere of cell cavity opens outer layer: fetal contribution to placenta inner: embryo implants into endometrium where inner cell becomes embryonic disc with 2 layers (ectoderm/endoderm) embryonic (day 15 - end of 8th week) organs formed! neurons connecting with neural tube & somites day 16: neural plate forms w/ 3 layers ectoderm: sensory organs, epidermis, & nervous system endoderm:gut, liver, pancreas & respiratory system mesoderm: dermis, muscles, skeleton, excretory & circulatory systems day 18: neural groove formed day 21: neural plate meets. forming neural tube! • neural crest separates from tube from ectoderm day 27: superior neural pore closes only superior rostral part form brain & caudal side form spinal cord neural tube differentiate association plate motor plate • • forms ventral forms dorsal horn of spinal cord horn of spinal sensory cord extras after 3rd month in utero • rate of spinal column exceeds spinal cord and nerve roots • lower nerve roots elongate to reach passage (lumbosacral nerves) somites : divide into myotome, dermatome, sclerotome myotome: skeletal muscle dermatome: dermis sclerotome: vertebrae & skull 1.4 Development of the Nervous System 2 day 28: brain develops 3 enlargement stage : superior neuropore of neural tube closes forming 3 enlargements • forebrain develops into diencephalon: forms thalamus, hypothalamus, 3rd ventricle hindbrain • midbrain stays midbrain • cerebral aqueduct • develops into pons /cerebellum & medulla, 4th ventricle telencephalon: forms into cerebral hemispheres including basal ganglia, 100 days: telencephalon cerebral cortex, and lat ventricles 6 month: sulci begin to form 9 months: more sulci prominent day 40: 5 enlargement stage fetal stage week 9 - birth • formation of sulci & grooves in gyri (cerebral & cerebellar hemispheres) central canal forms ventricles cerebral hemispheres grow into a “c” shape (caudate nucleus in the lat ventricle) 4th fetal month - end of 3rd yr myelination: on axons of neurons in CNS & PNS • # of electrical signals • insulate neurons (protect) more myelinated axons.= faster response time end of 3rd year motor & sensory systems matured & cerebral myelination almost complete • 5 -7 y/o • prefrontal cortex maturing so more myelination 20 - 30 y/o • myelination of cerebral cortex cont. • brainstem / cerebellum first then cerebral cortex 50 y/o • help integrate info & purposeful action 1.5 ANS Overview peripheral nervous system visceral fxn ANS: maintain homeostasis • Somatic NS control blood flow, skeletal fxn Visceral NS breathing, digestion, metabolism, endocrine function, body temo, reproduction Enteric nervous system Sympathetic nervous system Parasympathetic nervous system receptors of the ANS receive & send out appropriate signals found in visceral & vascular regions generate response to signals sensed by receptors in periphery • send afferent signals to • central system send efferent signals to generate appropriate sympathetic, parasympathetic, hormonal response limbic system, hypothalamus, reticular formation in brainstem and spinal cord 4 main receptors • pressure & stretch • changes in BP in • profile in blood aorta or stretch of bladder change in chem • sense levels of O2, CO2, Hydrogen thermorecpetors nociceptors chemoreceptors mechanical • sense pain • sensitive to stretch, • sense altered temp internal/ external chem imb, or lack of blood supply signal levels below neck: signals to periphery to spinal cord through CNS to brain above neck: peripheral signals detected by CN then go toward brainstem, * 3 CN carrying autonomic signals * CN 7, 9, 10 for taste, sensation, & visceral function autonomic afferent signals converges in solitary nucleus in medulla (main visceral sensory nucleus) sent to medulla, pons for HR, respiration, and control of vasculature (reach hypothalamus, thalamus, amygdala, anterior insula) Hypothalamus: influences all system via pituitary gland, brainstem, and spinal cord • receives sensory info from periphery comparing to baseline to make changes in BP, electrolytes, temp, reproduction, metabolism, emergent response Limbic system: emotional control • amygdala • anterior insula thalamus: signal relay for amygdala & anterior insula efferent autonomic nervous system pathways target organ post-ganglionic pre-ganglionic • cell bodies w/in CNS • long axon • sends signal to post • • receives signal initiate change from pre ganglionic in the -ganglionic neuron peripher in periphery 1.6 ANS: Sympathetic Nervous System SNS: stimulate fight or flight efferent signals ensure blood supply, body temp, metabolism & visceral function • decrease increase • HR • digestion • pupils dilate to enhance vision • bladder fxn • blood rush to muscles • bowel fxn • sweating neurotransmitter shormone influence • cortisol • adrenaline • ACTH solitary nucleus & hypothalamus in charge location: thoracolumbar outflow • pre ganglionic neurons in thoracic & lumbar regions • T1-L2 • in lateral horn sympathetic: closer to spinal cord para: closer to target organ or at 3 ways thoracolumbar outflow affects organs • SNS direct connection to adrenal medulla allows for quick response in adrenal medulla to release *only organ that has this* neurotransmitters into blood signals go to thoracic viscera then • SNS indirect connection to target organ involves post ganglionic nerve within paravertebral ganglia periphery ex: heart, trachea, skin • • indirect connection seen in abdominal viscera & pelvic organs post ganglionic neuron closer to organ • stomach, liver, pancreas & intestines 3 Neurotransmitters SNS depends on • norepinephrine most common in SNS • if not released by adrenal acetylcholine used by • cholinergic neurons epinephrine medulla, post ganglionic neurons activated by ACH in SNS & PNS release & act on heart, BV, • pre ganglionic bronchi neurons release this • • released by adrenal medulla bind to adrenergic receptors neurotransmitter receptors (SNS) nictonic: acetylcholine attaches activating ANS, arousal, & motivation systems (on post ganglionic neurons) muscarinic : more involved in parasympathetic : Impact on Effector organs SNS 1.7 ANS Parasympathetic Nervous System parasympathetic division: rest & digest efferent signals • • regulate body • solitary nucleus & metabolism, & conservation regulated by hormones @ temp, ensure body energy hypothalamus visceral fxn aka: craniosacral outflow • pre ganglionic neurons in brainstem or sacral region • S2-S4 • closer or @ target organ • direct communication via autonomic plexus • focused on bowel, bladder, & reproductive fxn CN involved • 3, 7, 9 (Indirect) • 10 (direct) autonomic plexuses • responds to head, thoracic region, & abdominal vsicera *only one neurotransmitter* regulates glands, smooth muscles and slow HR • acetylcholine • both pre & post ganglionic release this • target organ also responds using muscarinic recpetors pt focus • PNS, Heart, BV, digestion, metabolism Brain Stem Rostral Get off bw 3-4 (midbrain) Get home at 5 (pons) Dinner 6-8 (bw pons and medulla) Sleep bw 9-12 (medulla) Caudal