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Class 3 The Nervous System and Somatic and Special Senses Peripheral Nervous System Cranial Nerves and Spinal Nerves Cranial Nerves •12 Pairs of nerves that originate on the brain. I - Olfactory II - Optic III - Oculomotor IV - Trochlear V - Trigeminal VI - Abducens VII - Facial VIII - Auditory IX - Glossopharyngeal X - Vagus XI - Accessory XII - Hypoglossal Spinal Nerves • 31 pairs of spinal nerves (mixed nerves) – 8 cervical (C1 – C8) C1 between skull and atlas – others exiting at intervertebral foramen – 12 thoracic (T1 – T12) – 5 lumbar (L1 – L5) – 5 sacral (S1 – S5) – 1 coccygeal (Co) Spinal cord Anterior median fissure Pia mater Denticulate ligaments Dorsal root Ventral root, formed by several “rootlets” from one cervical segment Arachnoid mater (reflected) Dura mater (reflected) Spinal blood vessel Stimulus Reflex Arc Skin 1 Receptor Interneuron 2 Sensory neuron 3 Integration center 4 Motor neuron 5 Effector Spinal cord (in cross section) Patellar Reflex Withdrawal Reflex Nerve Plexus • Where 2 or more nerves come together, are resorted, and form a new nerve • Include: – Cervical – Brachial – Lumbosacral Cervical Plexus C1 – C4 Brachial Plexus C5 – T1 Lumbosacral Plexus L1 – L4 & L4 – S3 Peripheral Nerves Phrenic Nerve Axillary Nerve Median Nerve** Ulnar Nerve Radial Nerve Musculocutaneous Nerve Sciatic Nerve** Femoral Nerve** Obturator Nerve Cervical plexus diaphragm armpit associated with carpal tunnel syndrome medial forearm posterior arm, lateral forearm, posterior hand muscles and skin of arm posterior thigh to bottom of foot to big toe; splits into Tibial and Fibular at knee; largest and longest nerve in the body; can often been impinged by the piriformis muscle anterior and lateral thigh pelvis Brachial plexus Lumbosacral plexus Dermatomes C2C3 NV C2C3 C2 C3 • A dermatome is a region of the skin supplied by a single spinal nerve. T2 C6 L1 L2 C8 C7 T1 L3 L4 L5 C4 C5 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 S2 C3 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L4 L3 L5 C4 C5 T2 C6 T1 C7 SS 4 3 L1 S1 L5 S5 C8 L2 S2 L3 S1 L4 ANTERIOR POSTERIOR Shingles Autonomic Nervous System Parasympathetic and Sympathetic Sympathetic Division “Fight or Flight” Thoracolumbar division it’s branches come from the T₁ – L₂ or L₃ Effects heart rate, breathing rate, sweating, pupil size, blood vessel size to skeletal muscle, adrenal gland secretions intestinal function and saliva Parasympathetic Division “Rest and Digest” CranioSacral Division it’s branches come from the CNs III, VII, IX, X and S₂, S₃, and S₄ Effects: •Increase Intestinal Activity and saliva •Decrease Heart Rate •Slower, deeper breathing •Constricts pupils Role of Massage Therapy in Autonomic Nervous System Function Stimulates a Parasympathetic response Relaxation! Relaxation! Relaxation! Exception: Pre-event Massage/Sports Massage – which is designed to “stimulate” the body to prepare it for the event about to take place Somatic and Special Senses 5 Types of Receptors: Chemoreceptors Detect chemical concentrations in an aqueous solutions ex) taste buds and receptors of the nose Pain Receptors Detect damage to tissue ex) free nerve endings throughout body Thermoreceptors Detect changes in temperature ex) receptors found throughout skin and more Mechanoreceptors Detect changes in pressure or movement ex) receptors found in skin, inner ear and more Photoreceptors Detect light energy ex) rods and cones – the visual receptors Sensations •All impulses (information) entering the CNS are virtually the same. • The brain sends the signals to specific areas of the brain for interpretation. •All sensation is subjective. •Sensation is projected back to the site of the original stimulus, which makes us think we sense it at that point. •Many senses will adapt, impulses rates will decrease. Somatic Senses Touch, Pressure and Vibration Temperature Sensation 2 categories of Thermoreceptors: Hot and Cold receptors. • Cold receptors – Most stimulated between 77º F and 41º F. Below that and area goes numb. • Hot receptors – Perceive hot sensations above 86º F and are most stimulated at 113º F. • Free Nerve Endings: Detect as burning sensation when temp is above 113⁰ or detect as numbing when temp is below 41⁰. • Thermoreceptors are found all over the body, with highest concentration found in the face and ears (hence why your nose and ears always get colder faster than the rest of your body on a chilly winter day). Pain Sensation • Acute Fibers (A-Delta fibers) – sharp, myelinated, remove stimulus & pain goes away • Chronic Fibers (C fibers) – dull, unmyelinated, remove stimulus & pain stays Visceral Pain and Referred Pain Regulation of Pain Impulses Endorphins and Enkephalins Our Natural Pain Killers – special chemicals that when released slow down the pain fiber impulses hence lessening pain. Muscle and Tendon Proprioception Muscle Spindles Golgi Tendon Organs Special Senses Sense of Smell Olfaction Sense of Taste Gustation Sense of Sight • Hyperopia (farsightedness) – difficulty focusing on objects near the face. • Myopia (nearsightedness) – difficulty focusing on distant objects. • Astigmatism - An irregular shaped cornea or lens prevents light from focusing properly on the retina. Images focus at multiple points on retina Sense of Hearing/Equilibrium Hearing Cochlea of the Inner Ear Organ of Corti – hearing receptor Static Equilibrium • As the head moves, the thick fluid above the receptor cells, weighted with otoliths, pulls on the cilia of the cells, generating a nerve impulse Dynamic Equilibrium • As the body spins or moves in different directions, the cilia bend as the head changes position, generating nerve impulses. EXAM REVIEW This…….is….…Jeopardy Nervous System Peripheral Nervous System Neurons The Brain Senses 100 100 100 100 100 200 200 200 200 200 300 300 300 300 300 400 400 400 400 400 Thank goodness!!!