Central Nervous System White vs gray matter :: Gray = cell bodies (processing); White = myelinated axons (communication) Primary motor cortex, Broca’s, premotor location :: Frontal lobe Innermost meninge :: Pia mater CSF is formed where :: Choroid plexus (ventricles) Ventral horn destruction causes :: Loss of motor output Same hemisphere fibers :: Association fibers Across hemispheres :: Commissural fibers (corpus callosum) Advantage of convolutions :: Increased surface area → more processing power Grooves :: Sulci Folds :: Gyri Groove dividing hemispheres :: Longitudinal fissure Frontal vs parietal lobe :: Central sulcus Parietal vs temporal :: Lateral sulcus Primary motor cortex :: Voluntary movement Premotor cortex :: Plans movement Primary sensory cortex :: Detects touch Somatosensory association :: Interprets sensation Visual area :: Vision Auditory area :: Hearing Prefrontal cortex :: Decision making/personality Broca’s area :: Speech production Controls temp, hunger, ANS :: Hypothalamus Substantia nigra location :: Midbrain Vital centers (heart, breathing) :: Medulla oblongata Sensory relay center :: Thalamus (gray matter) Basal nuclei function :: Initiate/stop movement, smooth motion Cerebellum role :: Coordination, balance, posture Limbic system location/function :: Around brainstem; emotion + memory RAS meaning/function :: Reticular Activating System; alertness STM → LTM factors :: Repetition, sleep, emotion, meaning CNS protection (4) :: Skull/vertebrae, meninges, CSF, BBB CSF formation/drainage :: Produced in ventricles → circulates → reabsorbed into blood Blood-brain barrier :: Tight capillaries + astrocytes Pyramidal tracts :: Motor pathways; cross at medulla Dorsal vs ventral roots :: Dorsal = sensory; Ventral = motor CSF location :: Subarachnoid space Spinal cord organization :: Gray inside; white outside Anterior vs posterior root signals :: Anterior = motor; Posterior = sensory Cervical/lumbar enlargements :: Serve limbs Spinal cord location :: Vertebral foramen Filum terminale :: Anchors spinal cord ⸻ Sensation & Integration Sensation vs perception :: Sensation = detection; Perception = interpretation Sensory modality :: Type of stimulus Mechanoreceptors :: Touch/pressure Thermoreceptors :: Temperature Chemoreceptors :: Chemicals Nociceptors :: Pain Naked nerve endings :: Free endings (pain/temp) Encapsulated endings :: Wrapped (touch/pressure) 3 steps of sensation :: Stimulus → receptor → signal to brain Meissner’s corpuscles :: Light touch receptors Proprioceptor example :: Muscle spindle; detects stretch/body position Pressure receptor :: Pacinian corpuscle (encapsulated) Thermal receptor distribution :: Uneven Touch receptor distribution :: Uneven Referred pain :: Pain felt elsewhere Pain receptors :: Nociceptors Brain maps based on :: Sensitivity (not size) 3-neuron sensory pathway :: 1st: receptor → spinal cord 2nd: spinal cord → thalamus 3rd: thalamus → cortex Motor pathway neurons :: 2 neurons Upper: brain → spinal cord Lower: spinal cord → muscle Ascending pathways :: Sensory to brain Descending pathways :: Motor from brain