Human Anatomy (Chapters 16 & 17) PDF

Human Anatomy Chapter 16 Nervous Tissue 1 Part I Nervous System Divisions ◼ Central nervous system (CNS) ❑ Brain ❑ Spinal cord ◼ Peripheral nervous system (PNS) ❑ Cranial nerves involve all structure except those in CNS ❑ Spinal nerv...

Human Anatomy Chapter 16 Nervous Tissue 1 Part I Nervous System Divisions ◼ Central nervous system (CNS) ❑ Brain ❑ Spinal cord ◼ Peripheral nervous system (PNS) ❑ Cranial nerves involve all structure except those in CNS ❑ Spinal nerves ❑ Others 2 Functions of Nervous System ◼ Sensory function: to sense changes in the internal and external environment through sensory receptors. ❑ Sensory (afferent) neurons serve this function. Stowards > - CNS ◼ Integrative function: to analyze the sensory information, store some aspects, and make decisions regarding appropriate behaviors. spiral cord brain ~ ❑ Association or interneurons serve this function. ◼ Motor function is to respond to stimuli by initiating action. ❑ Motor(efferent) neurons serve this function. laway (from spinal cord) 5 Part II HISTOLOGY OF THE NERVOUS SYSTEM 6 Overview of nervous tissue ◼ Nervous tissue consists of two type of cells: ❑ Neurons Perform the function of the nervous system ❑ Neuroglia Support, nourish and protect the neurons 7 Neurons Functional unit of nervous system Have capacity to produce action potentials &transmit nerve impulse 1. Parts of neurons ❑ Cell body DCBA - ❑ Dendrites ❑ Axon 8  receivesignsa CB transmit to - Axon 9 Neuroglia Small but 5 to 50 more numerous than neuron Have NO electrical excitability or action potential Six types of Neuroglia ◼ Four in CNS ◼ astrocytes > form - blood brain barrier , protect brain cells ◼ oligodendrocytes > - protect CNS ◼ microglia > engulf - ◼ ependymal cells > - produce (SF ◼ Two in PNS & of impulses ◼ Schwann cells > - protect neurone propagation ◼ Satellite cells> - support 10  CNS Neuroglia Reference found in brain & CNS around wrap blood vessels to form blood brain barrier. ~ phagocytes lies of in ventricles brain Fig 16.6 & central canal Copyright@Tortora 11 Myelination ◼ Myelin sheath ❑ A multilayered lipid and protein covering around some axons that insulates them and increases the speed of nerve impulse conduction. ◼ Axons with myelin sheath are said to be myelinated. ◼ Axons without this cover are called unmyelinated. Two types of neuroglia produce myelin sheaths: ❑ Schwann cells in the PNS ◼ Nodes of Ranvier ❑ Oligodendrocytes in the CNS Fig16.7 copyright@Tortora 12 Collections of Nervous Tissue ◼ Cluster of neuronal Cell Bodies ❑ Ganglion (in PNS) ❑ Nucleus (in CNS) ◼ Bundles of Axons ❑ Nerve (in PNS) ❑ Tract (in CNS) ◼ Gray and White Matter (CNS) ❑ White matter – Myelinated axons ❑ Gray matter – Cell bodies, dendrites, unmyelinated axons, neuroglia 13 Cluster of neuronal Cell Bodies ↑ Fig 18.8 copyright@Tortora Fig 21.13 14 copyright@Tortora Tract (in CNS) ↓ X bundles of axon 15 Gray and White Matter Fig 16.9 Copyright@ Tortora 16 Chapter 17: The Spinal Cord and Spinal Nerves 17 Part I SPINAL CORD ANATOMY 18 Protective structures Provide protection to the spinal cord and provide physical stability. ◼ Vertebral column ◼ Meninges a. Dura mater, in b. Arachnoid mater, Can c. Pia mater ◼ Epidural , space, subdural space and subarachnoid space 19 Spinal Cord Anatomy 20 Spinal Cord Anatomy 21  External Anatomy of the Spinal Cord In adult, spinal cord extends from the medulla oblongata to the superior border of the second lumbar vertebra (L2). ❑ Two enlargements: cervical and lumbar Conical shape ❑ Conus medullaris: end part of spinal cord ❑ Filum terminale: anchors the spinal cord to the coccyx ❑ Cauda equina: The roots of lumber, sacral and coccygeal regions ❑ Posterior (dorsal) root & anterior(ventral) root ❑ Posterior (dorsal) root ganglion ❑ Spinal nerve 22 Spinal nerve enlarge part - nerve root 24 Internal Anatomy of the Spinal Cord D ◼ Anterior median fissure ◼ Posterior median sulcus ◼ Gray commissure ◼ Central canal ◼ Gray matter -- Anterior, posterior & lateral gray horns ◼ White matter -- Anterior, posterior & lateral white columns 25  Internal Anatomy of Spinal Cord * need to know their name & how to draw. butterfly/H containsaxon cominansent each I column D small space middle part & cluster all of body - motor neurone 26 Part II SPINAL NERVE 27 Overview of Spinal Nerves & motor Contain sensory neurones. ◼ 31 pairs; mixed nerves. ◼ Cervical (C1-C8), thoracic (T1-T12), lumbar (L1-L5), sacral (S1-S5) and coccygeal (Co1). 28 Distribution of Spinal Nerves ◼ Branches: Spinal nerves branch and their branches are called rami: ❑ Posterior (dorsal) ramus ❑ Anterior (ventral) ramus ◼ Plexuses: a network of axons Anterior rami form plexuses, except T2-T12. ❑ Cervical plexus ❑ Brachial plexus ❑ Lumbar plexus ❑ Sacral plexus ◼ Intercostal nerves: anterior rami of T2-T12 30 31 Cervical Plexus ◼ Formed by the anterior rami of C1-C5. ◼ supplies the skin and muscles of the head, neck, and superior part of the shoulders and chest. ◼ Phrenic nerves - important nerves from the cervical plexuses. supply motor fibers to the diaphragm. 33 Brachial plexus ◼ Formed by the anterior rami of C5-C8 & T1. ◼ Supplies the shoulders and upper limbs. ◼ Important nerves that arise from the brachial plexuses are ❑ Axillary nerve ❑ Musculocutaneous nerve X ❑ Radial nerve ❑ Median nerve ❑ Ulnar nerve 34 Lumbar Plexus ◼ Formed by the anterior rami of L1-L4. ◼ I Supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs. ◼ Femoral nerves, obturator nerves. 37 Sacral Plexus ◼ Formed by the anterior rami of L4-L5 and S1-S4. ◼ Supplies the buttocks, perineum, and lower limbs. ◼ Gives rise to the largest nerve in the body- the sciatic nerve. # 38 Distribution of Nerves from the Lumbar and Sacral Plexuses -Fut I Hamstring. Fem S Sciatic nerve nerve - 39 Part III SPINAL CORD PHYSIOLOGY 41 Sensory and Motor Tracts X test Reference naming ◼ The name of the tract often indicates its location in the white matter and where it begins and ends. ◼ The white matter contains both sensory and motor tracts. ◼ Sensory tract ❑ The spinothalamic tract ❑ The posterior column: gracile fasciculus, cuneate fasciculus ◼ Motor tract ❑ Direct tract: lateral corticospinal, anterior corticospinal and corticobulbar tracts ❑ Indirect tract: rubrospinal, tectospinal, vestibulospinal, lateral reticulospinal, and medial reticulospinal tracts ↳ maintain balance. 42 Reference 43 Human Anatomy Chapter 18: The Brain and Cranial Nerves 44 Part I BRAIN ORGANIZATION, PROTECTION, AND BLOOD SUPPLY 45 Major Parts of the Brain ◼ Brain stem ❑ continuation of the spinal cord; consists of the medulla oblongata, pons and midbrain. ◼ Cerebellum J. As ❑ second largest part of the brain. ◼ Diencephalon 1/ ❑ gives rise to thalamus, hypothalamus and epithalamus. ◼ Cerebrum ❑ largest part of the brain. 46 Protective Coverings of the Brain ◼ The cranium ◼ The cranial meninges: dura mater, arachnoid mater and pia mater. Three extensions of the dura mater separate parts of the brain: a) Falx cerebri separate the two cerebral A hemispheres. b) Falx cerebelli separate the two cerebellar J A - hemispheres. c) Tentorium cerebelli separate the cerebrum -A from the cerebellum. 48 Brain Blood Flow and the Blood- Brain Barrier ◼ Brain receives approximately 20% of the total blood supply. ❑ Internal carotid and vertebral arteries carry blood - to the brain. ❑ Internal jugular veins return blood from the brain. - 51  Blood-Brain Barrier ◼ Blood-brain barrier (BBB) protects brain from harmful substances. ❑ BBB consist mainly of tight junctions that seal together the endothelial cell of brain capillaries, along with a thick basement membrane around the capillaries. ◼ Astrocytes surround the capillaries, maintain the tight junctions 52 Blood-brain barrier (BBB) ❑ Permeability: ◼ A few water-soluble substances, such as glucose, amino acids, ions (Na+, Cl-, Ca2+, H+), gases cross the BBB by active transport. ◼ Lipid-soluble substances, such as steroids, fatty acid, alcohol, most anesthetic agents easily cross BBB. ◼ Other substances, like protein, antibiotic drugs, antibodies, microorganisms, e.g. bacteria, fungi, viruses, or parasites, can hardly or can’t pass BBB. 53 Part II CEREBROSPINAL FLUID 56 Overview of Cerebrospinal Fluid (CSF) ◼ Clear fluid. ◼ Circulates through cavities in the brain (ventricles) and the spinal cord (central canal) and also in the subarachnoid space. ◼ Functions of CSF: ❑ Absorbs shock and protects the brain and the spinal cord. ❑ Helps transport nutrients and wastes from the blood and the nervous tissue. 57 Ventricles Are four CSF-filled cavities within the brain. ❑ 2 Lateral ventricles: cerebral hemispheres. ❑ 1 Third ventricle: diencephalon. ❑ Cerebral aqueduct: midbrain. connect ❑ 1 Fourth ventricle: brain stem and the cerebellum. 58 Location of ventricles within a transparent brain 59 Formation of CSF in the Ventricles ◼ Ventricles are lined by ependymal cells and choroid plexuses. Theuroglia) ◼ Choroid plexuses ❑ networks of capillaries in the walls of the ventricles. ◼ Plasma is drawn from the choroid plexuses through ependymal cells into the ventricles to produce CSF. 60 Pathways of circulating cerebrospinal fluid 61  Circulation of CSF Reference ◼ CSF from the lateral ventricles → interventricular foramina → third ventricle → cerebral aqueduct → fourth ventricle → subarachnoid space or central canal. ◼ CSF is reabsorbed into the blood by arachnoid villi. ◼ Reabsorption = formation → maintainintracranial pressure is constant. 62 Formation and Circulation of CSF in the Ventricles 63 Parts of the Brain 1. Brain stem 2. Cerebellum 3. Diencephelon 4. Cerebrum 64 https://www.biomanbio.com/HTML 5Quizzes/physioquizzes.html 65