Ch 3: Anatomy of the Nervous System Jan 16, 2013 Ch 3: Anatomy of the Nervous System

Divisions of the Nervous System CNS Brain & spinal cord PNS Nerves outside CNS

PNS SNS ANS Interacts with the outside world; skeletal muscles Afferent nerves Incoming sensory info Efferent nerves Outgoing motor signals ANS Controls body’s internal environment ventral dorsal

ANS Regulates the internal body processes 2 kinds of efferent nerves: Sympathetic nerves Stimulate, organize & mobilize energy “fight or flight” Arousal Parasympathetic nerves Conserve energy; bring back to base levels “rest & digest” Relaxation

ANS Appendices 1 & 2 (pg. 491-492)

Neuro Quirk!!

The 12 Cranial Nerves Appendix 3 (pg. 493) While most of the PNS project from the spinal cord, 12 pairs come from the brain aka Auditory

Functions of the 12 Cranial Nerves Appendix 4 (pg. 494) Olfactory Smell Optic Sight Oculomotor Eye movement & pupil constriction Trochlear Eye movement Trigeminal Facial sensations & chewing Abducens Facial Taste, facial expression, tears, salivation Vestibulocochlear/Auditory Hearing & balance Glossopharyngeal Salivation & swallowing Vagus Abdominal & thoracic organs Accessory Neck, shoulders & head Hypoglossal Tongue movement

Functions of the 12 Cranial Nerves http://faculty.washington.edu/chudler/cranial.html for fxns

Nervous System Breakdown Fig 3.2

Nervous System Breakdown

Protecting the Brain Under the hard skull, 3 meninges help protect the brain Dura mater A tough leathery membrane Arachnoid membrane Spider web-like membrane Beneath it is the subarachnoid space that contains numerous blood vessels & CSF Pia mater Delicate membrane adhering directly to the brain’s surface

Protecting the Brain Cerebrospinal Fluid (CSF) Cushions the brain Produced by the choroid plexus One interconnected reservoir of CSF Fills the subarachnoid space, central canal of the spinal cord & ventricles of the brain Lateral ventricles (2) 3rd ventricle Cerebral aqueduct 4th ventricle Hydrocephalus: a condition where a buildup of CSF causes brain to expand

Protecting the Brain Blood-Brain Barrier (BBB) Prevents most toxic substances in the blood from passing into the brain Tightly packed cells of the blood vessel walls prevent proteins & large molecules from getting through

Neuroanatomical Directions Described in relation to the spinal cord 3 axes Anterior-posterior Dorsal-ventral Medial-lateral

Neuroanatomical Directions Be careful! Humans are a little tricky. Superior-inferior

Neuroanatomical Directions

Neuroanatomical Directions Proximal-distal Brain Slices: Horizontal section Frontal section Sagittal section Cross section

Spinal Cord Made of gray matter & white matter Gray: cell bodies White: myelinated axons Spinal nerves (31 pairs) attach to the spinal cord Their axons attach at the dorsal or ventral roots Dorsal: sensory Ventral: motor Efferent or afferent??

Major Structures of the Brain Brain Stem: Medulla Pons Cerebellum Cerebral aqueduct Thalamus Hypothalamus Cerebral cortex

Brain Stem: Medulla Pons Cerebellum Tracts carrying signals between brain & body Pons Cerebellum “little brain” Important in sensorimotor functions; precise movement control; coordination

Brain Stem (cont.) Cerebral aqueduct Thalamus Hypothalamus Connects 3rd & 4th ventricles Thalamus 2 lobes joined across the 3rd ventricle Sensory relay nuclei Receive signals from sense, process them & send them to the cortex Then get feedback from the cortex Hypothalamus Regulates motivated behaviors (sleep, sex, eating) Via hormone release from pituitary gland

Cerebral Cortex Cerebral hemispheres Gray & white matter Gyri & sulci (in humans) Fissures Longitudinal, central, lateral Corpus callosum Connects the 2 hemis

Cerebral Cortex 4 lobes of the brain Frontal Parietal Occipital PFC Parietal Occipital Temporal