Organization and Functions of the Nervous System

1. Organization and Functions of the Nervous System

2. Nervous System Divisions • CNS (central nervous system) • Brain, Spinal Cord • 12 pairs of cranial nerves (originate from cranium) • PNS (peripheral nervous system) • Somatic nervous system • 31 pairs of spinal nerves • Autonomic nervous system • Afferent and Efferent Nerves

3. 12 cranial nerves

4. Autonomic Nervous System

5. Sympathetic Division Exits Thoracic-Lumbar region of SC Norepinephrine in postganglionic synapses Fight-or-Flight Response Elevated hr, bp Pupil dilation Increased sweat gland activity Dry mouth Increased blood flow to muscles Parasympathetic Division Exits Cranial and Sacral regions of SC Acetylcholine in postganglionic synapses Energy Conservation Decreased hr, bp Pupil constriction Salivation Gastric Secretion Autonomic Nervous System

6. Protection of the CNS • Meninges (3 protective layers) • Dura Mater • Arachnoid Membrane • Pia Mater • Cerebrospinal Fluid • Buoyancy and Shock Absorption • Ventricles and subarachnoid space

7. Ventricular System

8. Dissection Planes

9. NeuroanatomyDirectional Terminology • Anterior – Posterior (Front –Back) • Dorsal – Ventral (Top – Bottom) • Medial – Lateral (Middle –Side) • Superior –Inferior (Above – Below)

10. Spinal Cord

11. Brain Divisions

12. Four Cerebral Lobes

13. Midsagittal View of Brain

14. Ventral Surface of Brain

15. Cerebral Cortex

16. Basal Ganglia • Three Main Components • Caudate Nucleus • Putamen • Globus Pallidus • Major Functions • Motor Control • Somatosensory-Motor Integration • Diseases of the BG • Parkinson’s Disease • Huntington’s Disease

17. Limbic System • Limbic Structures: a group of structures surrounding the brain stem • Cingulate Cortex • Hippocampus • Amygdala • Mammillary Bodies • Anterior Hypothalamus • Fornix • Functions • Emotions • Memory

18. Diencephalon • Thalamus • Two lobes at the anterior portion of the brain stem surrounding the third ventricle, joined by massa intermedia • Interconnected with Cerebral Cortex and with Cerebellum • Major Sensory Relay • Vision: Lateral Geniculate Nucleus • Hearing: Medial Geniculate Nucleus • Touch: Ventral Posterior Nucleus • Smell: Medial Dorsal Nucleus • Taste: Ventral Posterior Nucleus

19. Diencephalon • Hypothalamus • Located below the anterior thalamus • Contains several subdivisions and interconnected with limbic system regions • Detection of need states, involved in hormone and temperature, fluid & nutrient regulation

20. Brain Stem • Brain Stem—midbrain + hindbrain (minus the cerebellum)

21. Tectum (“roof”) relays visual and auditory information and controls simple reflexes, eye and ear orientation movements superior colliculi (“little hills”)—relay visual information inferior colliculi—relay auditory information Mesencephalon (Midbrain)

22. Mesencephalon (Midbrain) • Tegmentum (“floor covering”) • Substantia nigra—integration of voluntary movements • Red nucleus—controls basic body movements • Reticular formation—controls arousal and consciousness • Raphé system

23. The Hindbrain

24. The Hindbrain • Metencephalon • Pons—a “bridge” for many fibers passing from one side of the brain to the other. • Contains sensory fibers, fibers from the cortex to cerebellum, and fibers that relay information on sleep, arousal, muscle tone, and dreaming. • Cerebellum—involved in the development and coordination of movement • Myelencephalon • Medulla Oblongata • Cranial nerve nuclei • Regulates basic life functions (e.g., respiration, heart rate, vomiting, salivation)

25. Cerebellum • Components • Vermis • Lateral zone • Flocculonodular lobe • Cell Layers • Molecular Layer • Purkinje Cell Layer • Granule Cell Layer • Major Functions • Balance • Motor Coordination • Timing and sequencing of rapid movements • Sensorimotor Learning • Cognition?