Central Nervous System I- The Brain- Essentials PDF

Nervous System Introduction; Central Nervous System I: The Brain Essentials Course Objective Histology: Interpret micrographs by recognizing important components of cells and tissues to more fully understand how organs and organ...

Nervous System Introduction; Central Nervous System I: The Brain Essentials Course Objective Histology: Interpret micrographs by recognizing important components of cells and tissues to more fully understand how organs and organ systems function. Nervous System: Describe how the body communicates by identifying anatomical structures and tracing pathways of the nervous system in order to aid in medical diagnoses when these systems are compromised.  Lecture Learning Objectives 1. Identify which organs comprise the CNS vs the PNS 8. List/diagram the meningeal layers and spaces from superficial to deep to relate 2. Explain the different divisions of the nervous surrounding/supporting structures to the CNS system (anatomical and functional) and practice the associated terminology 9. Compare neural tissue (gray and white matter), linking its contents to its location and function 3. List the 3 components of a neuron and their primary characteristics. Link these components to 10. Visually identify the gross anatomical structures the locations you will find them. of the brain 4. Match the 4 types of neurons with their 11. Recall the organization of the brain and its characteristics and what nervous pathways they subdivisions, their primary functions (in blue) are located within (motor/sensory) linking functions to specific structures 5. Draw-out and label a schematic of somatic 12. Recall the location (lobe and/or gyrus) and sensory and motor neuron innervation pathway, primary roles of the cerebral functional and focusing on the differences between sensory and association areas and describe their differences motor and the location of cell bodies vs. 13. Define the three types of tracts found in cerebral axons/nerves white matter, focusing on what structures they 6. Describe the composition of nerves and their connect associated structures 14. Create a flow-chart for the flow of CSF through 7. Explain the difference of myelination in the PNS the CNS and recognize the roll of CSF and CNS Nervous System Overview  Nervous System System for interpretation and control of your body in reaction to your external and internal environments Includes sensation and motor responses Mostly comprised of nervous tissue Neurons and supporting glial cells Anatomical divisions Central Nervous System (CNS) Brain (cerebrum, brainstem, and cerebellum) and spinal cord Peripheral Nervous System (PNS) Cranial nerves, spinal nerves, peripheral nerves, and ganglia Gray’s Basic Anatomy, Moore et al. (2018)  LO 1 Functional Categories Processes information: Sensory = afferent (arrives at CNS) a. Somatic and Special Sense- Consciously perceived from external environment b. Visceral- Unconsciously perceived (mostly) from internal environment Information is processed and evaluated in CNS Respond to information: Motor, efferent (exits CNS) a. Somatic - Voluntary response to skeletal muscle b. Visceral - Involuntary response to internal organ muscle Gray’s Basic Anatomy, Moore et al. (2018)  LO 1 Functional Divisions Somatic (soma= body) Autonomic Sensory external environment Sensory from internal environment Motor to skeletal muscle Motor to smooth muscle in organs, some cardiac muscle, and glandular cells Effects are mostly conscious, voluntary or reflexive Effects are involuntary and automatic Sensory Sensory Central External Somatic Nervous Autonomic Internal Divisions of the Division (or Division Environment System Division Environment subdivisions) (CNS) Parasympathetic Motor Motor Sympathetic Neurons  LO 2 Neurons Neurons (nerve cells) Specialized to respond to environmental changes Nerve impulses- method of communication between neurons via electrical impulses Require glial cells to survive High metabolic rate Most are amitotic Vary greatly in size and shape Junquiera’s Basic Histology, Mescher (2018)  LO 2 Neuron Composition Cell body (soma) - Comprise gray mater Contain: Single nucleus and prominent nucleolus Chromatophilic (Nissl) substance- large masses of organelles related to protein syntheses in cytoplasm Dendrites Numerous elongated cellular processes Specialized to receive stimuli from other neurons at synapses Axon- Comprise white mater and nerves Single long process that originates at axon hillock, sends information Can also receive impulses  LO 2 Neuron Composition Contextualized Cell body (soma) - Comprise gray mater, ganglia, and nuclei Dendrites Upper central nervous system Basal nuclei Axon- Comprise white mater, nerves, tracts Spinal cord cross-section  LO 3 Structural Classification of Neurons a. Multipolar neuron 1 axon, 2+ dendrites Most common, motor Example? b. Bipolar neuron 1 axon, 1 dendrite Special senses Example? Junquiera’s Basic Histology, Mescher (2018)  LO 3 Structural Classification of Neurons c. Unipolar (pseudounipolar neuron) 1 process that bifurcates to CNS and PNS All sensory but special senses d. Anaxonic neuron Many dendrites, no true axon Regulate electrical changes, do not produce action potential Brain and retina Junquiera’s Basic Histology, Mescher (2018)  LO 4 Functional Classification of Neurons 1. Sensory neurons Receive stimuli from receptors (PNS → CNS) Somatic, autonomic/visceral, special sensory Unipolar 2. Interneuron 2 In CNS, form networks Multipolar or anaxonic Cell bodies located in gray matter, axons in Cell body white matter 3. Motor neurons (CNS → PNS) 3 Send impulses to effector organs (muscle 1 fibers; glands) Somatic or autonomic/visceral Multipolar Clinically Oriented Anatomy, Moore et al. (2018) Nerves!  LO 5 Peripheral Nerves Nerve A bundle of axons outside the CNS, surrounding CT, and blood vessels Protective CT Endoneurium- surrounds axon and myelin if present Perineurium- surrounds fascicle Epineurium- surrounds nerve or fascicle bundle Nuclei Collection of neuron cell bodies inside the CNS Ganglion Collection of neuron cell bodies outside the CNS Clinically Oriented Anatomy, Moore et al. (2018)  LO 7 Myelination Larger axon/nerve fibers are enclosed within myelin sheaths (myelinated) Narrow gaps between myelin sheaths are neurofibril nodes (nodes of Ranvier) Neurolemmocyte are also known as Schwann cells Clinically Oriented Anatomy, Moore et al. (2018)  LO 7 Myelination PNS myelination Myelin formed by neurolemmocytes (Schwann cells) CNS myelination Myelin formed by olgodentrocytes which form internodes on many axons Smallest diameter axons are unmyelinated and covered in processes from adjacent glial cells Junquiera’s Basic Histology, Mescher (2018) Context Example 1- Typing- Somatic Portion of brachial plexus a) Sensory neurons- primary neurons Tactile sensory cells in your Median fingers respond to the feeling of nerve in the the keyboard by sending signals upper limb to afferent sensory nerves. Sensory information travels through the peripheral nerves in the upper limb, through the brachial plexus, then spinal nerves. Enter the dorsal root of the spinal cord.  Example 1- Typing- Somatic b) Interneuron- secondary and tertiary neurons Information is carried though the spinal cord in an ascending spinal cord pathway, bundles of interneuron nerve fibers which create white mater. Enter brainstem, filtered by the thalamus, and travel to gray mater in post-central gyrus of the parietal lobe. Communicate with neuronal cell bodies in the pre-central gyrus of the frontal lobe via cerebral tracts.  Example 1- Typing- Somatic c) Motor neurons Signals from motor neurons in pre- frontal gyrus exit through cerebral white mater. Travel through the brainstem then inferiorly through a descending spinal cord pathway. Pathway fibers will synapse with motor neurons in anterior horn gray matter of spinal cord beginning of peripheral motor nerves. Travel through brachial plexus, nerves in the upper limb to the muscles of the hand to place the fingers on the keys.  Example 2- Heart Rate- Visceral/Autonomic Sensory neurons (PNS→ CNS) Chemoreceptor sensory cells in your carotid artery sense the C02 levels in your blood. Afferent sensory information travels through the glossopharyngeal (IX) nerve into the brainstem to the solitary nucleus. Synapsing occurs here. Interneuron (CNS) Interneurons transmit information in the brainstem to either the hypothalamus and cerebrum for a parasympathetic responses, or the remain in the brainstem for an immediate sympathetic response. Motor neurons (CNS → PNS) Information synapses on efferent motor neuron bodies, travel and exit via the vagus nerve (CN X) or sympathetic nerves Carry autonomic information to alter the rate of contraction in the heart Central Nervous System CNS Supporting Structures  LO 8 and 10 Cranial Meninges and Meningeal Spaces Connective tissue that a. Separates brain from cranium b. Protects and encloses blood supply c. Contain cerebrospinal fluid (CSF) Cerebral sinuses d. Form dural venous sinuses- large veins 1. Dura mater- thick outer layer 1 2. Arachnoid mater- thin web-like 2 layer 3. Pia mater- thin inner layer 3 adhered to CNS Cerebral meninges  LO 8 Cranial Meninges and Meningeal Spaces Superficial 1. Periosteum and bone 2. Epidural space - potential space 3. Dura mater Dense irregular CT Periosteal (superficial) and meningeal (deep) layers Separate to form dural venous sinsus 4. Subdural space - potential space 5. Arachnoid mater 6. Subarachnoid space Deep 7. Pia mater Junquiera’s Basic Histology, Mescher (2018)  LO 10 3 1. Periosteum and bone 2. Dura mater 2 3. Arachnoid mater 1  LO 8 and 10 Falx cerebri Cranial Dural Septa Meningeal layers extend between cerebral and cerebellar lobes as flat partitions Diaphragma sellae Stabilization and support Most contain venous sinuses Falx cerebri Separates cerebral hemispheres Falx cerebelli Tentorium cerebelli Separates occipital and temporal lobe from cerebellum Falx cerebelli Divides cerebellar hemispheres Diaphragma sellae Roof for sella turcica Tentorium cerebelli Cerebral Anatomy and Function  LO 9-10 The Brain Body’s control and coordination center Parts of the brain 1. Cerebrum (brain will include diencephalon) 2. Cerebellum 3. Brainstem Gray Organization of neural tissue A. Gray matter- neurons cell bodies, dendrites, and unmyelinated axons Cortex Basal nuclei Brainstem nuclei White B. White matter- myelinated axons Tracts Peduncles  LO 11 Subdivisions of the Brain and Brainstem 1. Cerebrum 2. Cerebellum 3. Diencephalon 4. Mesencephalon (midbrain) 5. Pons 6. Medulla (medulla oblongata)  LO 11 Subdivisions of the Brain and Brainstem Diencephalon 1. Cerebrum 2. Cerebellum 3. Diencephalon 4. Mesencephalon (midbrain) 5. Pons 6. Medulla (medulla oblongata)  Big Themes Cerebrum- Somatic motor and Brainstem- highway for sensory incoming sensory and outgoing Diencephalon- Relay station and motor pathway Mesencephalon- somatic motor, visual, auditory, sleep cycles, and Sleep, somatic sensory filter, temperature master autonomic control Pons- motor and sensory tracts, cranial nerve nuclei, respiration Medulla oblongata- Autonomic nuclei Cerebellum Coordination, control, and patterns  LO 10 Cerebrum (Telencephalon) Gyri, sulci, and fissures Longitudinal cerebral Longitudinal fissure fissure Right and left cerebral hemispheres Connected by tracts of axons, largest in the corpus callosum  LO 10 Cerebrum (Telencephalon) Frontal lobe Bounded by posterior at precentral gyrus and central sulcus, inferior at lateral sulcus Parietal lobe Bounded by postcentral gyrus, inferior at lateral sulcus Temporal lobe Bounded superior at lateral sulcus Occipital lobe Insula Deep to lateral sulcus  LO 12 Functional areas- Specific structures of cerebral cortex that have distinct motor or sensory roles Postcentral gyrus Precentral gyrus Association areas- Connected to primary motor and sensory cortical regions and integrate, interpret, and store information - In lobe adjacent to functional areas Clinically Oriented Anatomy, Moore et al., 2018  LO 12 Frontal lobe: Somatic Motor Parietal lobe: Somatic Sensory F: Primary motor cortex- Precentral gyrus- F: Primary somatosensory cortex- Postcentral gyrus- voluntary (somatic) motor control Touch, pressure, pain, and temperature A: Coordinate learned, skilled motor A: Sensory of texture, temperature, pressure, and activities object shape Occipital lobe: Vision F: primary visual cortex A: Visual information of color, movement, and form to identify what we see Gnostic area Gnostic area- integrates all sensory, visual, and auditory information from parietal, occipital, and temporal lobes Insula- Taste F: Primary gustatory cortex Temporal lobe: Hearing and smell F: primary auditory and olfactory cortex A: Sound and store memories of sound Clinically Oriented Anatomy, Moore et al., 2018  LO 10/11 Head and tail of Cerebral Nuclei caudate nucleus (Basal nuclei) Paired, irregular masses of gray matter buried within central white matter Claustrum Subconscious body movement a and somatic motor coordination; b emotion, behavioral activities, and development of moods Caudate Amygdaloid body Lentiform a. Putamen b. Globus pallidus Claustrum Lentiform Transverse section  A LO 10/11 Limbic System- Collective name for structures involved with motivation, emotion, and memory Fornix Function: Process and experience emotions Cingulate gyrus Hippocampus Anatomy: Forms a ring Fornix around diencephalon Cingulate gyrus Parahippocampal gyrus P Hippocampus Fornix Amygdaloid body Parahippocampal gyrus Fornix Anterior Mammillary bodies Mammillary body Posterior Amygdaloid body Hippocampus  LO 13 CNS White Matter Tract: Bundles of axons that serve as information highways and connect CNS structures Association tracts Connect cerebral cortex in same hemisphere Arcuate- within lobes Longitudinal- between lobes Will not be asked to Commissural tracts label tracts. Know what Connect cerebral hemispheres type connects different Ex., Corpus callosum structures Projection tracts Connect cerebral cortex to inferior brain regions and spinal cord Ex., Cerebral peduncles (from cerebrum to brainstem) Diencephalic and Brainstem Anatomy and Function  LO 10/11 Thalamus Diencephalon Epithalamus Hypothalamus Function: Relay and switching center for sensory and motor pathways for visceral activities Epithalamus- secrete melatonin and connect limbic system to other parts of the brain Pineal gland - endocrine gland that secretes melatonin Thalamus - somatic sensory filter Connected by an interthalamic adhesion  LO 10/11 Diencephalon Thalamus Epithalamus Hypothalamus - master autonomic Hypothalamus control center Master control of internal environment Heart rate, blood pressure, digestive activities, and respiration Master control of endocrine system Secretes hormones that influence or are stored in the pituitary gland Regulate body temperature Control emotional behavior Control food intake Control water intake Regulation of sleep-wake cycle Infundibulum holds pituitary gland  LO 10/11 Brainstem Function: Bidirectional passageway for all tracts (axons that share similar origin and destination) extending between the cerebrum and the spinal cord Anatomy: 1. Mesencephalon (midbrain) 2. Pons 3. Medulla oblongata  LO 10/11 Mesencephalon (Midbrain) a Function: b Pathway for motor axons from primary motor cortex (peduncles) M Visual and auditory sensation processing (colliculi) a Anatomy: b Midbrain Tectal plate- two cranial nuclei that control reflex turning of the head and Cerebral peduncles the eyes a. Superior colliculi- “visual reflex center” Cerebellar peduncles b. Inferior colliculi- “auditory reflex center” Posterior-lateral view  Cranial nerve nuclei LO 10/11 Pons Function: Contains sensory and motor tracts that connect brain and spinal cord Pons House many of the cranial nerve nuclei Respiration: Regulate rate and depth of Pons Cerebral peduncles breathing Influence and modify Cerebellar peduncles medulla’s respiration activity Anterior view  LO 10/11 Medulla Oblongata (medulla) Function: Autonomic nuclei (group of neurons) location Cardiac center- heart rate and strength of contraction M Vasomotor center- blood pressure Respiratory center- respiration rate, influenced by pons Cerebral peduncles Cerebellar peduncles Coughing, sneezing, salivating, swallowing, gagging, and vomiting Anatomy: 1. Pyramids 1 Anterior view Cerebellum Anatomy and Function  LO 10/11 Cerebellum Function: Coordinates and “fine-tunes” skeletal muscle(somatic) movement for patterns and smoothing movement Equilibrium and posture Receives proprioceptive information about position from muscles and joints, sends to cerebrum Anatomy: Right and left hemispheres; vermis (v); cerebellar peduncles Superior Cerebellum Cerebellar peduncles V L R R L Inferior Posterior view Anterior view Ventricular System  LO 14 Lateral Ventricular System Spaces within the central nervous system that carry Third cerebrospinal fluid Third Cerebral aqueduct Fourth Lateral ventricles Cerebrum Third ventricle Diencephalon Cerebral aqueduct Mesencephalon Cerebral aqueduct Fourth ventricle Pons, medulla, cerebellum Fourth  LO 14 Cerebrospinal Fluid Buoyancy Lateral Protection Environmental stability Third Flow of CFS 1. Lateral ventricles Cerebral 2. Interventricular foramen aqueduct 3. Third ventricle Interventricular foramen Fourth 4. Cerebral aqueduct 5. Fourth ventricle Lateral aperture 6. Median aperture – central canal Median aperture 7. Lateral apertures- subarachnoid space