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A&P Turk CENTRAL AND PERIPHERAL NERVOUS SYSTEMS EMBRYONIC DEVELOPMENT OF NERVOUS SYSTEM ectoderm, neural plate neural groove neural fold neural tube central canal and ventricles of the CNS neural crest forebrain, midbrain, and hindbrain VENTRICLES cerebral spinal fluid Ventricles Central canal subarachnoid space CEREBRAL HEMISPERES gyri sulci fissures cerebral cortex motor areas, sensory areas, and association neurons White matter Gray matter Commissural fibers corpus callosum Association fibers Projection fibers DIENCEPHALON Thalamus hypothalamus infundibulum pituitary gland limbic system autonomic nervous system epithalamus pineal gland BRAIN STEM Midbrain Pons medulla oblongata CEREBELLUM ELECTROCEPHALOGRAM (EEG) MENINGES Meninges dura mater arachnoid membrane pia mater epidural space subdural space subarachnoid space CEREBROSPINAL FLUID CNS buoyancy protection waste removal choroid plexus stability of chemical environment BLOOD BRAIN BARRIER perivascular feet of the astrocytes endothelial cell of the capillaries circumventricular organs third and fourth ventricles FUNCTIONS OF SPINAL CORD conduction locomotion cerebral cortex central pattern generators control of reflex activity ANATOMY OF SPINAL CORD foramen magnum vertebral canal L1 31 pairs of spinal nerves cervical region lumbosacral region cauda equina GRAY MATTER OF SPINAL CORD dorsal (posterior) horns ventral (anterior) horns gray commissure central canal filled with CSF interneuron lateral horn WHITE MATTER OF THE SPINAL CORD Spinal tracts Ascending carry sensory First order neurons – ganglion Second dorsal horn thalamus or cerebellum Third order neurons order neurons thalamus cerebrum Descending pathways and tracts Direct System interneurons or ventral horn neurons Indirect System HOMEOSTATIC IMBALANCES OF CNS Transient ischemic attacks (TIAs) Cerebrovascular accident (CVA) Alzheimers disease Parkinsons Disease dopamine-releasing neurons Huntingtons disease HOMEOSTATIC IMBALANCES OF CNS Poliomyelitis ventral horn motor neurons, Amyotrophic Lateral Sclerosis – Lou Gehrig’s Disease Spinal cord injuries paralysis paresthesias Anencephaly Spina bifida COMPONENTS OF PNS afferent fibers efferent fibers somatic skin, skeletal muscles, bones and joints visceral blood vessels, glands, and viscera receptor sense organ GENERAL PROPERTIES OF RECEPTORS transducers modality location intensity firing frequency number of nerve fibers firing higher threshold duration adaptation phasic receptors tonic receptors CLASSIFICATION OF RECEPTORS chemoreceptors thermoreceptors nociceptors mechanoreceptors Photoreceptors General senses Special senses interoceptors proprioceptors exteroceptors NERVE ENDINGS Unencapsulated nerve ending Encapsulated nerve ending Tactile (meissner) corpuscles – dermal papillae of skin Krause end bulb Lamellated (pacinian) corpuscles Ruffini corpuscles SPINAL NERVES Ganglia dorsal (sensory) root ventral (motor) root dorsal ramus ventral ramus meningeal branch intercostal nerve SPINAL NERVES nerve plexuses cervical – neck, shoulder, diaphram brachial – upper arm, forearm, hands radial – trauma causes wrist drop ulnar – funny bone, damage causes tingling of little finger median – damage makes objects hard to grab also musculocutaneous and axillary SPINAL NERVES nerve plexuses lumbar – abdominal wall muscles, thigh, buttock, genitals femoral – can cause problems walking if damaged obturator, also lateral femoral cutaneous, iliohypogastric, ilioinguinal, and genitofemoral sacral plexus – buttocks, pelvic structures, upper and lower leg, feet sciatic – actually 2 nerves (tibial and peroneal) also superior gluteal, inferior gluteal, posterior femoral cutaneous and pudendal (damage can affect erection and urination) coccygeal – pelvic floor and skin over coccyx REFLEXES peripheral effectors reflex arc Somatic receptors Afferent nerve fibers Interneurons Efferent nerve fibers Skeletal muscle Stretch reflex Tendon reflex Flexor reflexes
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