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Brain Anatomy and Spinal Cord Pathways Brooke Nash What We Will Cover 01. 02. 03. Brain Anatomy Spinal Cord Anatomy Spinal Cord Pathways 04. Spinal Cord Pathologies 01. BRAIN ANATOMY (simplified) Table of contents 01. 02. 03. Meninges Cerebrum Brainstem Dura, Arachnoid, Pia & Frontal, Temporal, ParietMidbrain, Pons, Medulla Dural Reflections and Occipital Lobes & Oblongata Functions 04. 05. 06. Blood Supply CSF Flow Brain Imaging Arterial supply and venous Axial, coronal, sagittal drainage MENINGEAL LAYERS https://www.thoughtco.com/brain-anatomy-meninges-4018883 DURA - Thick, Tough and Inextensible - Dural Reflections - Middle Meningeal Artery - Innervated (CN V) ARACHNOID - Loose connective tissue layer - Arachnoid Granulations = CSF Flow - Avascular, No Innervation PIA - Thin, adhered to the brain/ spinal cord - Highly vascularised - Impermeable to water MENINGITIS = Inflammation of the Meninges DURAL REFLECTIONS https://www.pinterest.co.uk/pin/472526185896259953/ Extradural Haemorrhages are confined by the Dural reflections, hence their lentiform shape QUESTION 1 A woman is visibly upset and brings her A FRONTAL LOBE husband to the GP. She explains that he has completely changed personalities in the Bast PARIETAL LOBE and now he is impulsive and rude. Thean husband, Mr Barker disputes this and tells OCCIPITAL LOBE you that his wife is overreacting. You take a collateral history from his wife and discover that his personality changed after he fell TEMPORAL LOBE off his ladder 3 months ago. E CEREBELLAR LOBE Damage to what part of Mr Barker’s brain could be causing this? QUESTION 1 A woman is visibly upset and brings her A FRONTAL LOBE husband to the GP. She explains that he has completely changed personalities in the Bast PARIETAL LOBE and now he is impulsive and rude. Thean husband, Mr Barker disputes this and tells OCCIPITAL LOBE you that his wife is overreacting. You take a collateral history from his wife and discover that his personality changed after he fell TEMPORAL LOBE off his ladder 3 months ago. E CEREBELLAR LOBE Damage to what part of Mr Barker’s brain could be causing this?THE CEREBRUMTHE BRAINSTEM ARTERIAL SUPPLY – CIRCLE OF WILLIS https://en.wikipedia.org/wiki/Circle_of_Willis QUESTION 2 Mrs Williams is a 78 year old female. She is an ex smoker with a 50 pack year history. LEFT ANTERIOR CEREBRAL ARTERY She presents to the ED with progressive left leg weakness. There is no arm weakness. LEFT MIDDLE CEREBRAL ARTERY You suspect an ischemic stroke. What artery is most likely to be affected. C RIGHT ANTERIOR CEREBRAL ARTERY D RIGHT MIDDLE CEREBRAL ARTERY E BASILLAR ARTERY QUESTION 2 Mrs Williams is a 78 year old female. She is an ex smoker with a 50 pack year history. LEFT ANTERIOR CEREBRAL ARTERY She presents to the ED with progressive left leg weakness. There is no arm weakness. LEFT MIDDLE CEREBRAL ARTERY You suspect an ischemic stroke. What artery is most likely to be affected. C RIGHT ANTERIOR CEREBRAL ARTERY D RIGHT MIDDLE CEREBRAL ARTERY E BASILLAR ARTERY ARTERIAL SUPPLY – CEREBRUM MAAL = Middle Arms, Anterior Legs https://teachmeanatomy.info/neuroanatomy/vessels/arterialhttps://www.sciencenewsforstudents.org/article/scientists-say-cortical-homunculus VENOUS DRAINAGE https://teachmeanatomy.info/neuroanatomy/vessels/venous-drainage/ CSF FLOW Functions of CSF 1. Protection 2. Buoyancy 3. Chemical stability Hydrocephalus = abnormal collection of CSF within the ventricles - Communicating (non-obstructive) = no flow obstruction - Non communicating (obstructive) = flow obstructed within the ventricular system (usually at the cerebral aqueduct) https://en.wikipedia.org/wiki/Ventricular_system BRAIN IMAGING - AXIAL https://www.kenhub .com/en/library/anat omy/normal-brain- mri BRAIN IMAGING - CORONAL https://mrimaster.co m/anatomy%20brai n%20coronal.html BRAIN IMAGING - SAGITTAL https://learningne urology.com/diag nostic- to-mri-brain/h- 02. SPINAL CORD ANATOMY (simplified) QUESTION 3 A 20 year old university student preseAts toC6/7 the ED with neck stiffness, photophobia and a non blanching rash. You suspect B T10/11 Lumbar Puncture to confirm the diagnosis.a At what level of the spinal cord should a L1/2 Lumbar Puncture be done? C D L3/4 E S1/2 QUESTION 3 A 20 year old university students presAnts C6/7 to the ED with neck stiffness, photophobia and a non blanching rash. You suspect B T10/T11 Lumbar Puncture to confirm. At what levela of the spinal cord should a Lumbar L1/2 Puncture be done? C D L3/4 E S1/2 SPINAL CORD The spinal cord finishes Origin of the Brachial Plexus growing at age 4, while the vertebral column finishes growing at age 14-18. This is why in adults the spinal cord occupies only the upper 2/3s of the vertebral canal Origin of Lumbar and Sacral Plexus L2 level, termination of the spinal cord SPINAL CORD CROSS SECTION DORSAL = SENSORY AFFERENT VENTRAL = MOTOR EFFERENT VASCULATURE OF THE SPINAL CORD https://www.researchgate.net/figure/An-Overview-of-Blood-Supply-to-the-Spinal-Cord-The-spinal-cord- predominantly-receives_fig4_311975365 D to the C → C to the S → S to the T WHITE MATTER https://commons.wikimedia.org/wiki/File:Spinal_cord_tracts_-_English.svg 03.1 ASCENDING SPINAL CORD SENSORY PATHWAYS: DCML & Spinothalamic QUESTION 4 Mr Jones is a 70 year old man with a hAstory Dorsal Column of prostate cancer who presents to his GP complaining that his legs are ‘feelingB Spinothalamic no difficulty. He also says that when heth dropped hot soup onto his legs he could Corticospinal feel it. However he cannot seem to feel his clothes on his legs. You conduct a lower limb neurological examination and reveal Reticulospinal that he also has reduced vibration and proprioception bilaterally. E Corticobulbar What pathway is affected in this patient? QUESTION 4 Mr Jones is a 70 year old man with a hisAory Dorsal Column of prostate cancer who presents to his GP complaining that his legs are ‘feeling B Spinothalamic no difficulty. He also says that when heth dropped hot soup onto his legs he could feel it. However, he cannot seem to feel his Corticospinal clothes on his legs. You conduct a lower limb neurological examination and revealD Reticulospinal that he also has reduced vibration and proprioception bilaterally. E Corticobulbar What pathway is affected in this patient? DORSAL COLUMN – FASCICULUS CUNEATUS 1st Order 2nd Order 3rd Order Decussation Function Lesion Carry sensory Begin in the Transmitthe Second order Fine touch Ipsilateral informationfrom nucleus cuneatus sensory signals neuronIn the Vibration loss of fine touch, the peripheral and travels to the from the thalamus medulla vibration and nerves fromT6 ventral in the internal Proprioceptio proprioception posterolateral capsule to the oblongata n levels and nucleus of the primary sensory above to the thalamus cortex Can be seen in medulla vitamin B12 oblongata deficiency They synapse with the nucleus cuneatus of the medulla PeripheralNerve → Medulla(decussate)→ Thalamus→ Cortex DORSAL COLUMN – FASCICULUS GRACILLIS st nd rd 1 Order 2 Order 3 Order Decussation Function Lesion Carry sensory Begins in the Transmitthe Second order Fine touch Ipsilateral informationfrom nucleus gracilis sensory signals neuronIn the Vibration loss of fine touch, peripheralnerves and then travel to from the thalamus medulla vibration and from below T6 the ventral in the internal Proprioceptio proprioception posterolateral capsule to the oblongata n to the medulla nucleus of primary sensory oblongata thalamus cortex Can be seen in vitamin B12 deficiency They synapse in the nucleus gracilis of the medulla PeripheralNerve → Medulla(decussate)→ Thalamus→ Cortex DORSAL COLUMN WHY IPSILATERAL LESIONS IN SPINAL CORD INJURIES ? The DCML runs up the entire cord and decussates in the medulla. Therefore, if there is damage to the cord, the signal cannot go past this damage to alert the brain, hence ipsilateral (same side) loss of vibration/proprioception/ light touch LATERAL SPINOTHALAMIC 1 Order 2 Order 3 order Decussate Function Lesion Arise from sensory Carry the sensory Carry the signals Second order Pain and Contralateral receptorsin the informationfrom from the thalamus neurondecussates sensory loss of periphery,enter the substantia through the within the temperature the spinal cord, gelatinosa to the internalcapsule pain and spinal cord temperature ascend1-2 ventroposterolate and to the primary vertebral levels ral nucleus of the sensory cortex and then synapse thalamus at the tip of the dorsal horn (substantia gelatinosa) PeripheralNerve → Spinal Cord(decussate)→ Thalamus→ Cortex ANTERIOR SPINOTHALAMIC ST nd rd 1 Order 2 Order 3 order Decussate Function Lesion Arise from sensory Carry the sensory Carry the signals Second order Crude touch Contralateral receptorsin the informationfrom from the thalamus neurondecussates and Pressure sensory loss of periphery,enter the substantia through the within the pain and the spinal cord, gelatinosa to the internalcapsule spinal cord temperature ascend1-2 ventroposterolate and to the primary vertebral levels ral nucleus of the sensory cortex and then synapse thalamus at the tip of the dorsal horn (substantia gelatinosa) PeripheralNerve → Spinal Cord(decussate)→ Thalamus→ Cortex SPINOTHALAMIC WHY CONTRALATERAL LESIONS IN SPINAL CORD INJURIES ? You can’t feel pain or temperature in the other side because of theLEVEL OF DECUSSATION . The pain/ temperature stimuli from the 1 order neuron on the unaffected side will travel to the spinal cord. This will synapse with the second order neuron which will then decussate to the other side. The second order neuron will try and run up this tract however, it will not be able to go the full way because there is a lesion. The brain will not be notified of a pain/ temperature stimuli and you will not feel it. Therefore there is a https://teachmeanatomy.info/neuroanatomy/pathways/ascending-tracts-sensory/ 03.2 DESCENDING SPINAL CORMotor Pathways: Corticospinal LATERAL CORTICOSPINAL Pathway Decussation Function Lesion of Spinal Cord Begin in the cerebralcortexwhere they receive inputs Decussatein the Supplies the IPSILATERAL Loss from: medullary musculatureof the of Motor Function •Primary motor pyramids body (distal •Premotor muscles) UMN Lesion signs •Supplementary motor - Muscle •Somatosensory weakness/ paralysis - Hyperreflexia Neurons converge and descendthroughthe internal - Hypertonia capsule Neuronspass through the crus cerebri of the midbrain, the pons and into the medullary pyramids Descend into the spinal cord and terminateat the ventral horn From the ventral horn, the LMNs go on to supply the ANTERIOR CORTICOSPINAL Pathway Decussation Function Lesion Begin in the cerebral cortex where they receive inputs Decussatein the Supplies the Rare from: spinal cord at the musculatureof the •Primary motor ventral horn body (trunk) •Premotor •Supplementary motor •Somatosensory Neurons converge and descendthroughthe internal capsule Neurons pass through the crus cerebri of the midbrain, the pons and into the medullary pyramids Descend into the spinal cord and terminateat the ventral horn From the ventral horn, the LMNs go on to supply theCORTICOSPINAL CORTICOBULBAR Pathway Decussation Function Lesion of Spinal Cord Arise from the lateral aspect of the primary Many of these fibres Motor control of the Unilateral lesion results motor cortex innervate the motor muscles of the face and in mild muscle neurons bilaterally neck; weakness Fibres pass through the internal capsuleto - CN V = Muscles of the brainstem Except for CN VII and Mastication Lesion to the UMN of CN IX which have - CN VII = Lower face CNXII = spastic paralysis - CN IX = Pharynx and Neurons terminateon the motor nuclei of contralateral Larynx of the contralateral cranial nerves and synapse with the LMNs innervation genioglossus (tongue which carry motor signals to the muscles of - CN XI = deviates to the the face and neck Sternocleidomastoid contralateralside) and Trapezius Lesion to the UMN of CN VII = spastic paralysis of muscles in the contralateral lower quadrantof the face Damage to these tracts are commonly seen in degenerative diseases They result in various types of dyskinesias EXTRAPYRAMIDAL TRACTS Extrapyramidal Tracts originate in the brainstem and carry motor fibers to the spinal cord They are responsible for INVOLUNTARY MOVEMENT: Muscle tone, balance, posture, locomotion PATHWAY DECUSSATION FUNCTION VestibulospinalArise from the vestibular nuclei (receivesinput from the organs No decussation Control balance and posture by of balance) innervating the anti gravity muscles Tracts convey this information to the spinal cord where it •Flexors of the arm remains ipsilateral •Extensors of the leg Reticulospinal The reticular formation of the pons and medulla gives rise toNo decussation Medial = facilitates voluntary the reticulospinalfibres movements and increasesmuscle tone Axons arising from the pontine reticular formation descend ipsilaterally as the medial/ pontine reticulospinal tract Lateral = inhibits voluntary movement and reduces muscle Axons arising from the medulla descended bilaterally in the tone lateral/ medullary reticulospinal tracts Rubrospinal Originates from the red nucleus Descendsinto the spinal cord Decussatesin the ventral Facilitates flexors and inhibits tegmental decussation extensors Tectospinal Begins in the superior colliculus (receivesinput from optic Decussateat the dorsal Coordinates movements of the nerves) tegmental decussation head in relation to visual stimuli Terminate at the cervical levels of the spinal cord 04. SPINAL CORD PATHOLOGIES Anterior, Posterior, Central, Brown Sequard ANTERIOR CORD SYNDROME POTENTIAL CAUSE SENSORY MOTOR Normally due to damage to the anterior Loss of pain and temperature Complete loss of motor spinal artery (trauma, disc prolapse, at and below the level of the function below injury tumour, something cutting off the injury bilaterally level bilaterally vascular supply) Due to loss of an anterior and Due to loss of lateral and lateral spinothalamic tracts anterior corticospinal The anterior spinal artery supplies the tracts anterior ⅔ of the cord Preservation of proprioception and vibration Bilateral Spastic Paralysis Dorsal column is still intact POSTERIOR CORD SYNDROME POTENTIAL CAUSE SENSORY MOTOR Posterior spinal artery injury → supplies Loss of vibration, Preserved motor function the posterior ⅓ of the spinal cord proprioception and light The corticospinal tract is Tumour growing on the back of the touch bilaterally intact spine, pressing on the spinal cord Loss of dorsal column behind pathway Syphilis (tabes dorsalis) RARE CENTRAL CORD SYNDROME POTENTIAL CAUSES SENSORY MOTOR Occurs in cervical Arms are affected more than the legs and Arms are affected more spondylosis and sacrum than the legs and extension injury sacrum Occurs in elderly patients Cape distribution → cervical region is the most Most common cord commonly affected (both arms, shoulders and Bilateral spastic syndrome upper chest but which sparing of the rest of theparalysis body) Bladder retention Loss of corticospinal Small lesions = bilateral loss of pain and tract temperature Loss of spinothalamic tracts The recovery pattern is Larger lesions = loss of pain and temp, light lower limbs, bladder, touch, proprioception upper limbs and then Loss of dorsal column and spinothalamic tracts sensory function QUESTION Mr Cole was found by paramedics in thA Bilateral loss of Motor Function street with a knife wound to the back which is suspected to have only affecBed Contralateral loss of Pain & Temp suspected to have Brown Sequardd. He is Syndrome. Which of the following Contralateral loss of Vibration & symptoms would you expect him to have? Proprioception Ipsilateral loss of Crude Touch and D Pressure E Contralateral loss of Motor Function QUESTION Mr Cole was found by paramedics in thA Bilateral loss of Motor Function street with a knife wound to the back which is suspected to have only affecBed Contralateral loss of Pain & Temp suspected to have Brown Sequardd. He is Syndrome. Which of the following Contralateral loss of Vibration & symptoms would you expect him to have? Proprioception Ipsilateral loss of Crude Touch and D Pressure E Contralateral loss of Motor Function BROWN SEQUARD SYNDROME POTENTIAL CAUSE SENSORY MOTOR This occurs when a knife is stabbed Ipsilateral loss of vibration anIpsilateral loss of motor through half of the spinal cord proprioception below the function below the level of injury the injury (rare, not seen much in clinical practice) Contralateral loss of pain and temperature below the level of the injury GOOD RESOURCES ●Teach me Anatomy / Teach Me Physiology ●Kenhub ●MRI Master ●Radiopedia ●2 Minute Neuroscience/ Neuroscientifically Challenged ●Physiopedia ●Case 14 LecturesThanks! Do you have any questions? nashb3@cardiff.ac.uk including icons by Flaticon and infographics & images bysgo, Freepik