FPP, Wk11, Lecture 1, Neuroanatomy and Physiology 1 2024-25 PDF

Foundations for Physiotherapy Practice 2024-25 Neuroanatomy and physiology Lecture 1 Learning Outcomes At the end of this session and associated independent study, the successful student will be able to: 1. Demonstrate a basic understanding of the anatomy and physiology of t...

Foundations for Physiotherapy Practice 2024-25 Neuroanatomy and physiology Lecture 1 Learning Outcomes At the end of this session and associated independent study, the successful student will be able to: 1. Demonstrate a basic understanding of the anatomy and physiology of the human nervous system 2. Describe the neuron and its structural classification 3. Discuss neural and chemical transmission in the nervous system 4. Discuss the anatomy of a peripheral nerve 5. Consider the clinical relevance of this neuroanatomy  Reference Book Readings on canvas Anatomy and human movement: structure and function UH FPP 2024-25  Have a pen and paper to hand UH FPP 2024-25 Nervous system Nervous system Central nervous system Peripheral Peripheral nervous system – nervous system – sensory division motor division Receptors Effectors  What are the types of cells in the nervous system??? What is neuron and what are its parts?? The nervous system micro structure Can you identify the features of a typical neuron Neuroglia - Supporting cells Neurons – Excitable cells UH FPP 2024-25  NOTES Neuroglia: supporting cells that surround the neurons insulate neuron and speed up conduction promote growth and healing support neurons in CNS e.g. oligodendrocytes, astrocytes (most abundant) in PNS e.g. satellite cells, Schwann cells form myelin sheaths Neurons to transmit the electrical signals  Neuron Cell Body (soma): Terminal Branches of Axon : Processes information (Axon Terminal)- End of the axon Dendrites: ‘Ears’ of the neuron - receives information Schwann Cell/Oligodendrocytes: Axon: Wraps around the axon Carries message to other cells Filled with Fat called Myelin Nodes of Ranvier seen between Forms insulating myelin myelin sheath  NOTES CNS contains 100 billion neurons/nerve cells 100 – 200,000 synaptic connections to a neuron Single output via the axon which then branches Neurons are typically large and complex Dendrites, hundreds used for input/receive signals from other neurons convey toward the cell body Neuron has single axon that generates nerve impulse and transmits them Axon terminal has NT that excite/inhibit the neighbouring neurons Myelin sheath increase the speed of transmission. Schwann cells in PNS, oligodendrocyte in CNS that produce the myelin. Myelination Lipid sheath surrounding neuron Function: Protect Insulate Increase speed of conduction PNS – Schwann cells CNS - oligodendrocytes  What would be the effect of disruption to the myelin sheath? Name a condition of the CNS where this is a problem What would be the effect of disruption to the myelin sheath? Slowing or loss of conduction of the impulse. Name a condition of the CNS where this is a problem. Multiple Sclerosis (MS). Classification of Nerve Fibres Function Afferent or sensory Efferent or motor Structural Classification Physiological characteristics Conduction velocity (proportional to its size) A fibres – fast (myelinated) B fibres fast but not as fast as A (myelinated) C fibres slow Classification of Nerve Fibres Physiological characteristics Myelinate d This Photo by Unknown Author is licensed under CC BY-SA  What type of fibres are connected to voluntary muscle?  Structural classification of neurons Neural Transmission Action Potential: The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell. The Resting Potential At rest, a neuron is polarised  It has an excess of negative charges on the inside and positive charges on the outside This uneven distribution of charges is separated by the cell membrane. The resting potential is - 70mV  Generating and propagating an action potential or nerve impulse · an electrical signal · generated / propagated along excitable cell membrane · CNS neurons work in pools to integrate incoming information before sending it on UH FPP 2024-25  Generating activity- the Action 1. Potential Action potential is initiated in the axon initial segment after neurotransmitter activates excitatory receptors in the neuron's dendrites and cell body. This depolarizes the axon initial segment 2. Stimulus causes sodium (Na+) channels to open and the membrane depolarises 3. When the membrane contains more positive ions than negative ones (+30mV) sodium channels close 4. Potassium channels open and shift the membrane potential back towards resting levels- repolarisation 5. The membrane becomes hyperpolarised due to the loss of potassium ions. The potassium gates close. Generating and propagating an action potential or nerve impulse Neural Transmission - Action potential https://commons.wikimedia.org/wiki/File:Action_potentia l_propagation_animation.gif https://upload.wikimedia.org/wikipedia/commons/2/2f/A ction_potential_propagation_animation.gif https://www.youtube.com/watch?v=iBDXOt_uHTQ Atrtributed: John Schmidt [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)] UH FPP 2024-25 Chemical Transmission Chemical Transmission This Photo by Unknown Author is licensed under CC BY-SA Peripheral Nerves An aggregation of myelinated and unmyelinated axons Axons held together by fibrous sheets https://morelifehealth.com/articles/peripheral- neuropathy Anatomy of peripheral nerves Function of the connective tissue layers Endoneurium Elastic collagenous tissue. Fibres are longitudinal suggesting can protect axon from tensile forces. Axons themselves are seen undulate with in the endoneurium Perineurium Surrounds a fascicle acting to protect axons within as well as providing a mechanical and chemical barrier Considered most resistant to tensile forces but also arranged with some circular and oblique's fibres to protect from angulations created during motion especially at joints Fascicles run in wavy courses throughout the nerve Epineurium Outermost sheath which protects and cushions fascicles and their axons Internal epineurium facilitates gliding of fascicles on one another allowing for motion  Nerve Adaptation Nerves can’t tolerate endless stretch but they need to adapt to length changes in every day life of between 10-20%. Nerves also glide in their environment or bed of other soft tissues like muscle. Nerves are most vulnerable to compression and interruption of their blood supply. Prolonged stretch or compression can compromise this and pins and needles/ loss of function can result. This resolves quickly when restoring normality. Prolong the exposure and the symptoms take longer to settle. Clinical Relevance of Neuroanatomy Why do physiotherapists need to know about peripheral nerves Have you ever had pins and needles? You move – it goes – phew! Imagine being in a plaster cast and developing pins and needles initially and then the area going numb. Imagine not being able to wiggle your toes. Clinical Relevance of Neuroanatomy How might a patient present due to muscle weakness following a radial nerve palsy? UH FPP 2024-25  Clinical Relevance of Neuroanatomy How might a patient present due to muscle weakness following a radial nerve palsy? This is a peripheral nerve lesion. Wrist drop and inability to extend the fingers due to weakness in the wrist and finger extensor muscles UH FPP 2024-25 This Photo by Unknown Author is licensed under Clinical Relevance of Neuroanatomy How might a patient present due to a lesion of the spinal cord ie a spinal cord injury? This Photo by Unknown Author is licensed under CC BY-SA-NC Clinical Relevance of Neuroanatomy How might a patient present due to a lesion of the spinal cord ie a spinal cord injury? Where is the lesion is it complete or incomplete? Motor and sensory loss or abnormality below the level of the lesion UH FPP 2024-25 Revisit the Learning Outcomes At the end of this session and associated independent study, the successful student will be able to: Demonstrate a basic understanding of the anatomy and physiology of the human nervous system Describe the neuron and its structural classification Discuss neural and chemical transmission in the nervous system Discuss the anatomy of a peripheral nerve Consider the clinical relevance of this neuroanatomy