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CENTRAL AND PERIPHERAL NERVOUS SYSTEMS By Shruti Rajendra 4 year Medical Student – Imperial College London 07/11/2023 at 7:00pm @ BRITISHINDIANMEDICASSOCIATION @BINDIANMEDICS BRITISH INDIAN MEDICAL @BIMA ASSOCIATION BIMA Preclinical seriesWHO AM I Shruti Rajendra 4 year medical student at Imperial College Intercalating in Cardiology BScTOPICS COVERED I. Central Nervous II. Peripheral Nervous System System III. SBAsCentral Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø Enlargements 2539 8868Divisions of the Nervous System Nervous System Central Nervous Peripheral System Nervous System The Brain Spinal Cord Nerves GangliaCentral Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsOverview of the BrainParts of the Brain I. Forebrain Ø Cerebral hemispheres Ø Diencephalon II. Midbrain III. Hindbrain Ø Pons Ø Medulla Ø CerebellumLobes of the Brain Touch Pain Motor function Temperature Language Sense of limb position Cognitive function Attention Memory Processing visual information Processing auditory informationOther Lobes Limbic lobe Insular lobeMeninges • Dura mater Ø Meningeall • Arachnoid mater • Pia materCerebrospinal Fluid • Bathes brain and spinal cord 125 mls 500 mls • ______ volume of CSF produced at any one time; ______ volume of CSF produced per day Produced in: Collects in: Reabsorbed via: Choroid plexus of Subarachnoid Arachnoid villi lateral, 3 and 4 th space and into superior ventricles ventricles sagittal sinus MENTI Code : 16917140Central Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsOverview of the Spinal Cord Cervical (8) Thoracic (12) Lumbar (5) Sacral (5) Coccygeal (1)Spinal Cord Enlargements Cervical Enlargement: Upper Limbs Innervation Lumbar Enlargement: Lower Limbs InnervationCentral Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsSomatotopyCentral Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsDescending Tracts – Overview • Motor function • Corticospinal tract • 2 parts: Ø UMN: v Primary motor cortex Ø LMN: v Brainstem (head and neck) v Spinal cord (trunk and limbs)Descending Tracts – Location and Function • 2 parts to corticospinal tract: Decussation = Ø Anterior / ventral Crossing over of fibres Ø Lateral contralaterally • Anterior à trunk muscles • Lateral à limb musclesDescending Tracts – Pathway Common pathway Lateral corticospinal tract pathway Anterior corticospinal tract pathwayCentral Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsAscending Tracts – Overview • Sensory function Ascending Tracts Dorsal Column Spinothalamic Pathway Tracts Ventral Lateral Spinothalamic Tract Spinothalamic TractAscending Tracts – OverviewDorsal Column Pathways First order neurone Second order neurone Third order neuroneSpinothalamic Tracts First order neurone Second order neurone Third order neuroneCentral Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsOther Tracts Vestibulospinal – Head movement and position and mediates postural adjustments Tectospinal – Orientation of the head and neck during eye movements Reticulospinal – Control of breathing and emotional motor function Rubrospinal – Innervate lower motor neurones of the upper limbCentral Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Example Case Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsExample Case A 32-year old male patient has fallen onto his back from a ladder, whilst doing some DIY work at his home. He feels little to no pain on the left side of the body from the T5 level downwards. He also feels altered sensation of fine touch on the right side of his body from the same point downwards. He is able to move his left leg normally but has severely restricted movement of his right leg.Example Case A 32-year old male patient has fallen onto his back from a ladder, whilst doing some DIY work at his home. He feels little to no pain on the left side of the body from the T5 level downwards. He also feels altered sensation of fine touch on the right side of his body from the same point downwards. He is able to move his left leg normally but has severely restricted movement of his right leg.Example Case – Answer Right sided lesion at T5 level. • Pain is transmitted through the spinothalamic tract. This decussates immediately at the level of the spinal cord. So, no pain on left side from T5 downwards suggests right sided lesion at T5 level. • Fine touch is transmitted by dorsal column pathways. This decussates at the medulla. So, lack of sensation of fine touch on the right side suggests right sided lesion at T5 level. • The lack of movement in the right leg also suggests right sided lesion at T5 because the corticospinal tract travels upwards on the ipsilateral side before decussating at the medulla.Central Nervous System Introduction to the Nervous Systems Ascending Tracts: Other Tracts Ø Overview Ø Dorsal Column Pathways The Brain: Ø Spinothalamic Tracts Ø Overview Clinical Significance Ø Parts Ø Lobes Ø Other Lobes Ø Meninges Descending Tracts: Ø Overview Summary Table Ø Cerebrospinal Fluid Ø Location and Function Ø Pathway The Spinal Cord: Ø Overview Somatotopy Ø EnlargementsSummary Table Tracts Function Neurones Decussation Lesion Effect Lateral Motor – limb muscles UMN and LMN Medulla Tends to be same corticospinal side Ventral Motor – trunk muscles UMN and LMN Medulla Tends to be same corticospinal side Dorsal column Sensory – fine touch; 1 , 2 , 3 order Medulla Tends to be same pathways proprioception; vibration neurones side Lateral Sensory – pain; 1 , 2 , 3 order Spinal cord Tends to be spinothalamic temperature neurones opposite side Ventral Sensory – crude touch 1 , 2 , 3 order Spinal cord Tends to be spinothalamic neurones opposite sidePERIPHERAL NERVOUS SYSTEMPeripheral Nervous System Overview of the Peripheral Reflex Action Nervous System Peripheral and Somatic Peripheral Nerves: Nerves: Ø Structure Ø Peripheral nerves Ø v Conduction velocity Ø Somatic nerves v Axonal diameterOverview of Peripheral Nervous System Peripheral Nervous System Autonomic Somatic Nervous System Nervous System Sympathetic ParasympatheticPeripheral Nervous System Reflex Action Overview of the Peripheral Nervous System Peripheral and Somatic Peripheral Nerves: Nerves: Ø Structure Ø Peripheral nerves Ø Classification: Ø Somatic nerves v Axonal diametercityPeripheral and Somatic Nerves • Peripheral Nerves: Ø Cranial nerves à ___ pairs Ø Spinal nerves à ___ pairs • Somatic Nerves: skin and skeletal muscle Ø Afferent nerves à relay information _____ _______________________ Ø Efferent nerves à relay information __ _________________Peripheral Nervous System Reflex Action Overview of the Peripheral Nervous System Peripheral and Somatic Peripheral Nerves: Nerves: Ø Structure Ø Peripheral nerves Ø Classification: Ø Somatic nerves v Axonal diametercityPeripheral Nerves – Structure Endoneurium à internal layer à covers individual neurones Perineurium à middle layer à covers individual fascicle Epineurium à external vascular layer à covers entire nervePeripheral Neurones – Classification Reflex Action Overview of the Peripheral Nervous System Peripheral and Somatic Peripheral Nerves: Nerves: Ø Structure Ø Peripheral nerves Ø Classification: Ø Somatic nerves v Axonal diametercityReflex Action Involuntary coordinated pattern of muscle contraction and relaxation caused by a peripheral stimulusPeripheral Nervous System Reflex Action Overview of the Peripheral Nervous System Peripheral and Somatic Peripheral Nerves: Nerves: Ø Structure Ø Peripheral nerves Ø Classification: Ø Somatic nerves v Axonal diametercitySummary Table Tracts Function Neurones Decussation Lesion Effect Lateral Motor – limb muscles UMN and LMN Medulla Tends to be same corticospinal side Ventral Motor – trunk muscles UMN and LMN Medulla Tends to be same corticospinal side Dorsal column Sensory – fine touch; 1 , 2 , 3 order Medulla Tends to be same pathways proprioception; neurones side vibration Lateral Sensory – pain; 1 , 2 , 3 order Spinal cord Tends to be spinothalamic temperature neurones opposite side Ventral Sensory – crude touch 1 , 2 , 3 order Spinal cord Tends to be spinothalamic neurones opposite sideSBAsSBA 1 Which of the following is not associated with the central nervous system? A. Midbrain B. Spinal cord C. Cranial nerves D. Medulla MENTI Code : 16917140SBA 1 Which of the following is not associated with the central nervous system? A. Midbrain B. Spinal cord C. Cranial nerves D. MedullaSBA 2 How many spinal nerves do we have? A. 12 B. 31 C. 24 D. 62SBA 2 How many spinal nerves do we have? A. 12 B. 31 C. 24 D. 62SBA 3 Where is the substance that fills the subarachnoid space produced? A. Subarachnoid space B. Subdural space C. Choroid plexus of the ventricles D. 3 ventricleSBA 3 Where is the substance that fills the subarachnoid space produced? A. Subarachnoid space B. Subdural space C. Choroid plexus of the ventricles D. 3 ventricleSBA 4 A wasp is flying near a person’s eye and they need to contract the muscles around it to prevent it from touching their eye. Which tract is involved in this? A. Spinothalamic tract B. Dorsal column pathway C. Corticospinal tract D. Corticobulbar tractSBA 4 A wasp is flying near a person’s eye and they need to contract the muscles around it to prevent it from touching their eye. Which tract is involved in this? A. Spinothalamic tract B. Dorsal column pathway C. Corticospinal tract D. Corticobulbar tractSBA 5 A patient presents to A&E after a car accident. She complains of not being able to move her left arm, left hand, left side of the trunk and the left leg at all. She also complains that she does not feel any pain on the right side of her body, including her left hand, arm, trunk and leg. She notes that her head, neck and shoulders are unaffected. Where is the injury? A. Right-sided C3 lesion B. Left-sided C3 lesion C. Right-sided C5 lesion D. Left-sided C5 lesionSBA 5 A patient presents to A&E after a car accident. She complains of not being able to move her left arm, left hand, left side of the trunk and the left leg at all. She also complains that she does not feel any pain on the right side of her body, including her left hand, arm, trunk and leg. She notes that her head, neck and shoulders are unaffected. Where is the injury? A. Right-sided C3 lesion B. Left-sided C3 lesion C. Right-sided C5 lesion D. Left-sided C5 lesionTHANK YOU FOR LISTENING ANY QUESTIONS?? Email: shruti.rajendra20@imperial.ac.uk INSERT QR CODE FOR FEEDBACK FORM BIMA Preclinical series