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
61
