Clinical Neuroscience Week 1 – Embryological Development and Cell Pro

Week 1: Embryological Development and Cell Properties

• Neuroanatomy Key Terminology:

  • Nucleus: Group of neurons in CNS with similar function.
  • Ganglia: Group of neuronal cell bodies outside CNS with similar function.
  • Tract: Bundle of axons in CNS (e.g., corticospinal tract).
  • Nerve: Bundle of axons outside CNS.
  • Afferent: Incoming information.
  • Efferent: Outgoing information.
  • Gray matter: Tissue of nerve cell bodies and dendrites.
  • White matter: Tissue of nerve fibers with myelin sheaths.
  • Somatic nervous system: Afferent/efferent to skeletal muscle.
  • Autonomic nervous system: Afferent/efferent to smooth muscle & glands.
  • Sulci: Grooves (fissures are larger sulci).
  • Gyrus: Folds or ridges.

• CNS Organization:

  • Dorsal: Top of brain, back of spinal cord.
  • Ventral: Bottom of brain, front of spinal cord.
  • Rostral: Front of brain.
  • Caudal: Back of brain, toward the tail.
  • Medial: Midline of brain.
  • Lateral: Away from midline.
  • Horizontal Plane: Divides brain into upper/lower halves.
  • Sagittal Plane: Divides brain into left/right halves.
  • Coronal Plane: Divides brain into front/back halves.

• CNS Components:

  • Central Nervous System (CNS): Brain and spinal cord, surrounded by bone.
  • Peripheral Nervous System (PNS): Cranial nerves, spinal nerves, and peripheral nerves.

• Embryological Development Key Events:

  • Gastrulation (~18 days): Formation of ectoderm, mesoderm, and endoderm.
  • Neurulation (3-4 weeks): Formation of neural plate, folds, and tube; neural crest development.
  • Spinal Nerves (3-6 weeks): Differentiation into alar (sensory) and basal (motor) plates.
  • Brain Development (4-6 weeks): Formation of prosencephalon, mesencephalon, and rhombencephalon.

• Brain Regions:

  • Prosencephalon: Diencephalon (thalamus, hypothalamus) and telencephalon (cerebral hemispheres).
  • Mesencephalon: Midbrain.
  • Rhombencephalon: Cerebellum, pons, and medulla oblongata.
  • Optic outgrowth forms the eyes.

• Clinical Applications:

  • Spina Bifida: Neural tube closure failure, often in lumbar region.
  • Arnold Chiari Malformation: Herniation of cerebellar tonsils through foramen magnum.

• Cell Properties and Transmission:

  • Neuron Structure: Dendrites, soma, axon, presynaptic terminal, cytoskeleton (microtubules, neurofilaments).
  • Neuron Types: Multipolar, bipolar, pseudounipolar.
  • Neuron Areas: Input (dendrites, soma), conducting (axon, nodes of Ranvier, myelin), output (presynaptic terminal).
  • Nerve Communication: Synaptic input -> passive current -> action potential in axon -> neurotransmitter release.

• Ions and Channels: Sodium, potassium, chloride, calcium move across membranes. Ion channels (ligand-gated, voltage-gated, modality-gated). Ion pumps establish concentration gradients.

• Action Potential: Resting potential (-70 mV), local potential, action potential (all-or-none), repolarization, hyperpolarization.

• Synapses: Chemical (neurotransmitters), electrical (gap junctions).

• Neurotransmitters: Excitatory (acetylcholine, glutamate, catecholamines), inhibitory (GABA, endocannabinoids).

• Post-Synaptic Receptors: Ionotropic (fast), metabotropic (slow).

• Clinical Applications (cell properties): - Botox: Limits acetylcholine release. - Myasthenia Gravis: Autoimmune destruction of post-synaptic receptors.

• Non-neural Cells: Neuroglia (astrocytes, microglial cells, oligodendrocytes, Schwann cells). Myelination (insulates axon); Nodes of Ranvier (saltatory conduction).

• Clinical Applications (non-neural cells):

  • Multiple sclerosis: Demyelination in CNS.
  • Guillain-Barre Syndrome: Demyelination in PNS.

Week 2: The Cerebrum, Cerebral Cortex, Blood Supply, and Substructures

• Cerebrum and Cerebral Cortex Functions: Higher-level functions (touch, vision, hearing, speech, reasoning, emotions, learning, movement).

• Hemispheres: Left (dominant, logic, language), Right (non-dominant, creativity, spatial processing).

• Cerebral Cortex Key Areas: Motor (primary motor, premotor, supplementary motor), Sensory (somatosensory, visual, auditory, smell, taste, vestibular), Association (integration).

• Surface Features: Sulci (lateral, central, parietal-occipital, cingulate, calcarine), Lobes (frontal, parietal, occipital, temporal), Corpus callosum (connects hemispheres), Anterior commissure, Precentral gyrus (motor), Postcentral gyrus (sensory), Cingulate gyrus (limbic system), Cuneus (visual), Uncus (memory, smell), Thalamus (relay station).

• Inferior Aspect Landmarks: Longitudinal fissure, Olfactory bulbs, Optic chiasm, Midbrain, Poles (occipital, temporal, frontal).

• Lobes of the Cerebral Cortex:

  • Frontal Lobe: Cognition, behavior, emotions, language (Broca's), movement, executive functions. Damage leads to behavioral changes, depression, etc.
  • Temporal Lobe: Hearing, language (Wernicke's), memory, emotion. Damage to Language comprehension difficulties (Wernicke's), etc
  • Parietal Lobe: Sensory perception, spatial orientation, body position. Damage leads to disorientation.
  • Occipital Lobe: Visual processing. Damage leads to visual problems.
  • Insular Lobe: Sensory/Pain/Temperature, Emotional Regulation, Multi-Sensory Integration. Damage leads to sensory and pain perception issues.

• Functional Areas: Primary cortex, premotor cortex, somatosensory cortex, occipital lobe (Wernicke's and primary visual), auditory cortex, Broca's area, olfactory bulbs.

• Cortical Homunculus: Mapping of body onto cortex (primary motor, primary somatosensory); contralateral representation.

• Brain Blood Supply: Circle of Willis (alternative pathways), arteries (anterior cerebral, middle cerebral, posterior cerebral, vertebral), superior/inferior cerebellar arteries.

• Venous System: Cerebral veins drain to dural sinuses (superior sagittal, transverse, sigmoid).

• Cranial Meninges: Dura mater, arachnoid mater, pia mater; spaces (epidural, subdural, subarachnoid), dural reflections (falx cerebri, tentorium cerebelli, falx cerebelli).

• Clinical Applications (Stroke): Types (ischemic, hemorrhagic), signs/symptoms, NIH Stroke Scale, imaging (CT, MRI), medical management (tPA, thrombectomy), stroke location and symptoms (MCA, ACA, PCA, basilar, vertebral).

• Ventricles: Lateral ventricles, third ventricle, cerebral aqueduct, fourth ventricle; CSF flow; ventricular pathology (hydrocephalus).

Week 3: Brainstem and Cranial Nerves

• Brainstem: Midbrain, pons, medulla. Functions: Cardiovascular, respiratory, sleep, head/neck motor/sensory. Structures (midbrain: cerebral peduncles, tegmentum, tectum; pons: vertical tracts; medulla: nuclei, decussation)

• Vertical Tracts: Corticospinal, other motor pathways. Reticular Formation: regulates alertness, sleep, motor activity, autonomic function.

• Brain Blood Supply (Brainstem): Detailed arterial supply (internal carotid, posterior communicating, posterior cerebral, superior/inferior cerebellar, pontine, basilar, labyrinthine, anterior/posterior inferior cerebellar, anterior spinal, vertebral).

• Clinical Application (brainstem): Damage results in disorders of consciousness (coma, vegetative, minimally conscious states)

• Cranial Nerves (CN): All 12, function, sensory/motor/mixed, ipsilateral/contralateral deficits. Olfactory (smell), Optic (vision), Oculomotor (eye movements), Trochlear (eye movements), Trigeminal (facial sensation/mastication), Abducens (eye movements), Facial (facial expression, taste), Vestibulocochlear (hearing, balance), Glossopharyngeal (swallowing, taste), Vagus (swallowing, visceral sensations), Spinal Accessory (neck muscles), Hypoglossal (tongue movements). Clinical considerations, lesions, and deficits for each cranial nerve.

Week 4: The Spinal Cord

• Spinal Cord: General features (31 pairs of spinal nerves, conus medullaris, cauda equina), internal structure (gray matter: dorsal, lateral, ventral horns; white matter: columns), white matter components (sensory and motor tracts), longitudinal organization.
• Spinal Cord Reflexes: Stretch reflex (monosynaptic), reciprocal inhibition, flexor withdrawal (polysynaptic), stepping pattern generators.
• Descending Systems (upper motor neurons): From motor cortex, brainstem, basal ganglia, cerebellum.
• Spinal Cord and Peripheral Nerves: Peripheral nervous system components, nerve classification, dermatomes, myotomes, upper vs. lower motor neuron pathology (UMN vs. LMN).
• Clinical Application (spinal cord): Amyotrophic Lateral Sclerosis (ALS).
• Spinal Cord Regeneration: Peripheral (Schwann cells promote regrowth), central (glial scars inhibit regeneration).