Introduction to Neuroanatomy PDF

Introduction to Neuroanatomy Stacia Hall Thompson, PT, DPT, PhD, CS DPT 5600 Functional Neuroanatomy Lecture Objectives By the end of lecture, students will: 1. Describe the organization of the nervous system. 2. Identify the major components of the CNS & PNS. 3. Appreciate the CNS regions &...

Introduction to Neuroanatomy Stacia Hall Thompson, PT, DPT, PhD, CS DPT 5600 Functional Neuroanatomy Lecture Objectives By the end of lecture, students will: 1. Describe the organization of the nervous system. 2. Identify the major components of the CNS & PNS. 3. Appreciate the CNS regions & their function. 4. Describe how the structure & location of an area dictates its function. 5. Develop a basic understanding of how to draw and label the various portions of the nervous system. Did You Know? Aristotle (335 BC) believed the heart was the seat of mental processes. The function of the brain was to dissipate heat. Terms & Directions Terminology – See Worksheet CNS Olive Telencephalon PNS Pyramid Diencephalon White matter Pyramidal Midbrain Gray matter Geniculate Dorsal columns Tracts Putamen Mesencephalon Associations Subdural Subcortical white Nuclei Epidural matter Ganglion Cavernous sinus Basal ganglia Ventricle Ophthalmic Hypothalamus Motor Arachnoid Epithalamus Sensory Glial cells Choroid plexus Schwann Ipsilateral Dural sinus Oligodendrocyte Bilateral Corpus callosum Dendrodendritic  Ipsilateral/Contralateral/Bilateral Proximal/Distal Location Superior/Inferior Terms Medial/Lateral Horizontal, Coronal (frontal), Sagittal planes Directional Terms Above the Midbrain Anterior = Rostral Posterior = Caudal Superior = Dorsal Inferior = Ventral Below the Midbrain Anterior = Ventral Posterior = Dorsal Superior = Rostral Inferior = Caudal Development to Adult Brain Structures  Nervous System CNS Teleocephalon (Outer layer) Forebrain Brain and spinal cord (Prosencephalon) Diencephalon (Inner layer) Brain Midbrain (Encephalon) (Mesencephalon) Pons Hindbrain Medulla (Rhombencephalon) Cerebellum Dorsal Columns White matter Lateral Columns Anterior Spinal Cord Columns Gray matter Structure CNS Gray & White Matter  Central Nervous System Neuroglia Neuron Dendrites Gray matter White matter Perikaryon Cell body Nucleus Nucleus Cortex Telodendria (inside) Axons Axon (Surface) Not organelle Direction Tracts (up/down) This color-coded figure shows the four general Association (front/back) regions of a neuron. Commissure (left/right) Gray matter -Collection of cell bodies within the CNS Cerebral gray matter- collection of cell bodies in the cerebrum White matter- Collection of Axons (myelination) Basal nucleus, Cranial nerve nuclei Cell bodies in CNS surrounded by white matter  Nervous System PNS CNS Everything else Brain and Spinal cord Functional Divisions/Directions Afferent division Carries sensory information FROM PNS sensory receptors to CNS Efferent division Carries motor commands From CNS to PNS muscles and glands Spinal Cord and Peripheral Nerves  Nervous System PNS Sensory Motor Somatic Autonomic Voluntary Involuntary Special General (specific part of body) (many parts of body) Vision Olfaction Sympathetic Parasympathetic Taste Hearing Somatic Visceral Balance Superficial Deep Subcutaneous organs Locomotors Proprioception Sympathetic and Parasympathetic Parts and Pieces Brain  Cerebral Cortex Cerebral Cortex is made up of: Frontal lobe Parietal lobe Temporal lobe Occipital lobe Sulcus - Crevice Fissure - Deep sulcus Gyri - bumps/rises The Brain Six Major Regions of the Brain 1.Cerebrum 2.Cerebellum 3.Diencephalon 4.Mesencephalon 5.Pons 6.Medulla oblongata The Brain  Primary Sensory and Motor Areas Primary Motor Cortex Precentral gyrus Movement of contralateral side of body Primary Sensory Cortex Postcentral gyrus Sensation for Contralateral side of body Primary Visual Cortex Occipital lobe Along the Calcarine fissure Primary Auditory Cortex Temporal lobe Inside the Sylvian fissure Topographical Organization Cortical Homunculus Neurological "map" of the anatomical divisions of the body  Why do the features look weird?? The Body within the brain or the “Cortex Man” His body parts developed in proportion to the surface area of the cortical region dedicated to the control of specific functions For example: Afferent sensory nerves arriving from the hands Terminate over a large areas of the brain Results in homunculus’ hands being correspondingly large In contrast: Nerves emanating from the torso or arms Cover a much smaller area Results in torso and arms look small and weak Dr. Wilder Penfield Sensory & Motor Homunculus “HAL” Topographical Organization  Association Cortex Unimodal Association Cortex Mostly for a single sensory or motor modality Found adjacent to the primary areas Heteromodal Association Cortex Integrating functions from multiple modalities Can test these areas with the Mental Status Exam  Association Cortex Language: broken down into 2 phases: 1) Perceiving “Wernicke’s area” 2) Making ”Broca’s area” Listening: Perceived first in primary auditory cortex Reading Perceived primary visual cortex From here Association Fibers…..convey the information to: Wernicke’s area “Left hemisphere” Lesions in Wernicke’s area: Deficits in language comprehension Sensory aphasia Receptive aphasia Wernicke’s aphasia Broca’s area “Left hemisphere” Adjacent to primary motor cortex Involved in moving lips, tonuge, larynx Lesions in Broca’s area: Deficits in speech production Expressive aphasia Motor aphasia Broca’s aphasia Limbic System H.O.M.E Brainstem Brainstem Brainstem  DIENCEPHALON Brainstem THALAMUS Relay and processing centers for sensory information HYPOTHALAMUS Centers controlling emotions, autonomic functions, and hormone production MIDBRAIN Brain Processing of visual stem and auditory data Generation of reflexive somatic motor responses Maintenance of consciousness PONS Relays sensory MEDULLA OBLONGATA information to cerebellum and Relays sensory information to thalamus and thalamus to other portions of the brain stem Subconscious Autonomic centers for regulation of visceral somatic and visceral function (cardiovascular, respiratory, and motor centers digestive system activities) Brainstem and Cranial Nerves Spinal Cord  Posterior median sulcus Dorsal root Dorsal root White matter ganglion Central Gray C1 C2 canal matter Cervical spinal C3 C4 nerves C5 Spinal Ventral C6 Cervical nerve root Anterior median fissure C7 C3 C8 enlargement T1 T2 T3 T4 T5 T6 T7 Thoracic T8 Posterior spinal T9 median sulcus nerves T10 Lumbar T3 T11 enlargement T12 Conus L1 medullaris L2 Inferior Lumbar L3 tip of spinal L4 spinal cord nerves Cauda equina L5 L1 Sacral spinal S1 S2 nerves S3 S4 S5 Filum terminale S2 Coccygeal nerve (Co1) (in coccygeal ligament)  Typical Cross-Section of the Spinal Cord How do you know what you are looking at?? Use the following rules: 1) Lateral horn is present from T1-L2 2) Absolute number of nerve fibers in the white matter increases at each successive higher spinal segment 3) Fasciculi Cuneatus and Gracilis are BOTH present above T7 4) Grey matter is largest in Segments of the cervical and lumbosacral enlargements Such large structures require a massive innervation 5) When comparing the cervical and lumbosacral enlargements Dorsal horn at cervical levels is narrower than that in lumbar Ventral horn is broad in both Spinal cord Anterior median fissure Pia mater Denticulate ligaments Dorsal root Ventral root, formed by several “rootlets” from one cervical segment Arachnoid mater (reflected) Dura mater (reflected) Spinal blood vessel  Posterior white column Posterior gray horn Lateral Lateral Dorsal root white gray horn ganglion column Anterior gray horn Anterior white column The left half of this sectional view shows important anatomical landmarks, including the three columns of white matter. The right half indicates the functional organization of the nuclei in the anterior, lateral, and posterior gray horns.  Gray Matter and White Matter Sectional Anatomy of the Spinal Cord White matter Is superficial Contains myelinated Gray matter Surrounds central canal of spinal cord Contains neuron cell bodies, neuroglia Has projections (gray horns) Organization of Gray Matter Gray horns Posterior gray horns contain somatic and visceral sensory nuclei Anterior gray horns contain somatic motor nuclei Lateral gray horns are in thoracic and lumbar segments; contain visceral motor nuclei Gray commissures Axons that cross from one side of cord to the other before reaching gray matter Peripheral Nervous System  Posterior median sulcus Functional Organization Posterior gray of Gray Matter commissure The cell bodies of neurons in the gray matter of the spinal cord are organized into functional groups called nuclei. Somatic Sensory nuclei Visceral Visceral Motor nuclei Somatic Ventral root Anterior gray commissure Anterior white commissure Anterior median fissure The left half of this sectional view shows important anatomical landmarks, including the three columns of white matter. The right half indicates the functional organization of the nuclei in the anterior, lateral, and posterior gray horns. Peripheral Distribution of Spinal Nerves From interoceptors From exteroceptors, of back proprioceptors of back The dorsal root of each spinal nerve carries sensory information to The dorsal ramus carries the spinal cord. sensory information from the skin and skeletal Somatic muscles of the back. sensory nuclei The ventral ramus carries sensory information from the ventrolateral body surface, structures in the body wall, and the limbs. Dorsal root From exteroceptors, ganglion proprioceptors of body wall, limbs From interoceptors of body wall, limbs Rami communicantes Visceral Ventral sensory nuclei root = Somatic sensations = Visceral sensations The sympathetic nerve carries sensory information From interoceptors from the visceral organs. of visceral organs Peripheral Distribution of Spinal Nerves To skeletal Postganglionic fibers muscles of to smooth muscles, back glands, etc., of back The spinal nerve forms just lateral to the intervertebral foramen, The dorsal ramus contains where the dorsal somatic motor and visceral motor and ventral roots unite. Dorsal root fibers that innervate the skin and Dorsal root skeletal muscles of the back. ganglion The axons in the relatively large ventral ramus supply The ventral root of each the ventrolateral body spinal nerve contains the surface, structures in the axons of somatic motor and body wall, and the limbs. visceral motor neurons. To skeletal Visceral motor nuclei muscles of body wall, limbs Somatic motor nuclei Rami communicantes Postganglionic fibers to smooth muscles, = Somatic motor glands, etc., of body commands wall, limbs Sympathetic = Visceral motor ganglion commands The white ramus is the first branch from the spinal nerve and carries visceral motor fibers to a nearby sympathetic ganglion. Because Postganglionic fibers these preganglionic axons are myelinated, to smooth muscles, this branch has a light color and is therefore glands, visceral organs known as the white ramus. in thoracic cavity A sympathetic nerve contains preganglionic The gray ramus contains postganglionic and postganglionic fibers that innervate glands and smooth Preganglionic fibers fibers innervating muscles in the body wall or limbs. These fibers to sympathetic structures in the are unmyelinated and have a dark gray color. ganglia innervating abdominopelvic thoracic cavity. viscera  Organization of White Matter Tracts or fasciculi In white columns Bundles of axons Relay same information in same direction Ascending tracts Carry information to brain Descending tracts Carry motor commands to spinal cord What are Tracts?? Bundles of Axons moving within the CNS Three types of Tracts 1) Ascending/Descending fibers Vertical fibers (Axons) Run through brain and Spinal cord Connect Upper CNS to Lower CNS 2) Commissural fibers Transverse fibers (Axons) Connect the left and right hemispheres of the brain 3) Association fibers Connect cortical areas within the same cerebral hemisphere (Front & Back) Anterior/Posterior Connect Brain to Brain Typical Cross-Section of the Spinal Cord White matter is divided into 3 major areas: (Tracts can only run in these areas) Dorsal Column ONLY carries ASCENDING TRACTS Lateral Column Carries BOTH Ascending and Descending Tracts Anterior Column Carries BOTH Ascending and Descending Tracts Summary A basic understanding of the nervous system will aid in understanding the details later this semester.