Physio - Hindbrain, Midbrain, Subcortical Structures

Midbrain Overview and Anatomy

Brainstem Cross Sections: Midbrain, Pons, Medulla

中脳レベルの反応ー出現と

anatomy lecture 2 What are the three major divisions of the brain? What structures make up the brainstem? What is the largest portion of the brain? To which structure is the cerebellum attached? What does the brainstem connect? ⸻ Answers Forebrain, midbrain, hindbrain Midbrain, pons, medulla oblongata Cerebrum Brainstem Brain to spinal cord ⸻ Section 2 — Lobes of the Brain How many lobes are in each cerebral hemisphere? Name the four lobes of the brain. Which lobe controls voluntary movement? Which lobe controls sensation? Which lobe controls hearing? Which lobe controls vision? Which lobe is located posterior to the parietal lobe? Which lobe lies anterior to the central sulcus? Which lobe lies posterior to the central sulcus? ⸻ Answers Four Frontal, parietal, temporal, occipital Frontal lobe Parietal lobe Temporal lobe Occipital lobe Occipital lobe Frontal lobe Parietal lobe ⸻ Section 3 — Sulci and Fissures What is a sulcus? What is a gyrus? What is a fissure? What does the central sulcus separate? What does the lateral sulcus separate? What does the longitudinal fissure separate? ⸻ Answers A groove A ridge A deep groove Frontal and parietal lobes Temporal lobe from frontal and parietal lobes Right and left cerebral hemispheres ⸻ Section 4 — Corpus Callosum and White Matter What is the corpus callosum? What does the corpus callosum connect? What type of tissue is the corpus callosum composed of? What type of fibres connect the right and left cerebral hemispheres? What type of fibres connect areas within the same hemisphere? What type of fibres connect the brain to the spinal cord? What structure contains projection fibres linking the cortex to the brainstem? ⸻ Answers A bundle of nerve fibres Right and left cerebral hemispheres White matter Commissural fibres Association fibres Projection fibres Internal capsule ⸻ Section 5 — Cerebellum and Brainstem What is the function of the cerebellum? Where is the cerebellum located relative to the brainstem? Which part of the brainstem controls breathing and heart rate? Name three automatic functions controlled by the brainstem. ⸻ Answers Coordination and balance Posterior to the brainstem Medulla oblongata Breathing, heart rate, reflexes ⸻ Section 6 — Meninges and CSF (Very High Yield) Name the three layers of the meninges from outermost to innermost

blood supply to brain, stroke & midbrain

brainstem- midbrain

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

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dorsal midbrain structures of sheep brain

Midbrain