Peripheral nervous system

PNS, cranial nerves spinal nerves

1. PERIPHERAL NERVOUS SYSTEM BY SONI KUMARI SHAH

2. PNS The PNS consists of nerves and ganglia outside the brain and spinal cord. The main function of PNS is to connect CNS to the limbs and organs, essentially serving as relay station between brain & spinal cord and rest of the body. PNS consists of: 12 pairs of cranial nerves 31 pairs of spinal nerves

3. Cranial Nerves 12 pairs of nerves that arises from the brain are cranial nerves Name Nerve Type Function I Olfactory Sensory Smell II Optic Sensory Vision III Oculomotor Motor Movement of eye IV Trochlear Motor Moves eye V Trigeminal Both Face sensation. Mastication VI Abducent Motor Abducts the eye VII Facial Both Facial expression, taste VIII Vestibulocohlear Sensory Hearing, balance IX Glossopharyngeal Both Taste, gag reflex X Vagus Both Gag reflex, parasympathetic innervation XI Accessory Motor Shoulder shrug XII Hypoglossal Motor Swallowing, speech

4. Cranial Nerves S ome S ay M arry M oney B ut M y B rother S ays B ad B oys M arry M oney O hh O hh O hh T o T ouch A nd F eel V ery G ood V elvet. S uch H eaven!

5. Spinal Nerves 31 pairs of spinal nerves arises from the spinal cord 8 pairs cervical nerves 12 pairs thoracic nerves 5 pairs lumbar nerves 5 pairs sacral nerves 1 pair coccygeal nerves Parts of spinal nerves 1. Root: Dorsal Root Ventral Root 2. Trunk 3. Ramus And Branches: Dorsal Ramus Ventral Ramus

6. Spinal Nerve Plexuses S. N. Nerve Root Plexus Plexus supply to 1 C1-C4 C3-C5=Phrenic Cervical Scalp & neck, diaphragm 2 C5-T1 Brachial Arm 3 T2-T11 No plexus formed Intercostal nerves serve chest wall 4 T12-L4 Lumbar Abdominal wall, antero -medial thigh 5 L5-S1 sacral Posterior thigh, lower leg and foot

7. Autonomic Nervous System The autonomic or involuntary part of the nervous system controls involuntary body functions. The autonomic nervous system is separated into two divisions: • sympathetic (thoracolumbar outflow) • parasympathetic (craniosacral outflow).

8. Sympathetic Nervous System Originates in spinal cord and functions to activate the physiological changes in fight, flight or fright. Utilizes and activates the release of norerpnephrine in reaction. Parasympathetic Nervous System Originates in spinal cord and medulla and works with sympathetic nervous system. Functions to activate rest and digest response and return the body to homeostasis after fight or flight reaction. Utilizes and activates the release of acetylcholine.

9. Differences Between Sympathetic And Parasympathetic Nervous System S.N Sympathetic Nervous System Parasympathetic Nervous System 1 It is thoracolumbar in origin i.e originates from T1-L2 It is craniosacral in origin i.e originates from brainstem to S2, S3, S4 2 Ganglia are located in pre and paravertebral region. Ganglia are located in effector organ . 3 Preganglionic fibers are shorter & post ganglionic fibers are longer. Preganglionic fibers are longer & post ganglionic fibers are shorter. 4 Distribution of postganglionic fibers is wide. Distribution of postganglionic fibers is limited. 5 Its nerve ending are adrenergic in nature. Its nerve ending are cholinergic in nature. 6 It is active during fight, flight and fright. It is active during rest . 7 It dilates pupil. It constricts pupil. 8 It increases sweat production. No PS effect. 9 It increases heart rate. It decreases heart rate. 10 It dilates respiratory airways. It constricts respiratory airways. 11 It decreases secretion of saliva It increases secretion of saliva 12 It decreases peristalsis. It increases peristalsis. 13 It inhibits contraction of bladder wall. It stimulates contraction of bladder wall.

10. Pure sensory cranial nerves are III, IV,V I, II, III I, II, VIII II, III. VII Glossopharyngeal is one of cranial nerve. It is responsible for sense of Smell Taste Hearing Vision Largest cranial nerve in our body is Facial Trigeminal Vagus Olfactory Which of the following cranial nerve has longest route in periphery? I IV X XI

11. With the stimulation of parasympathetic nervous system the pupil will Dilated Constricted Neither Both The drowsiness after food intake is due to Increased blood flow to intestine Increased blood pressure Increased activity of liver Increased blood flow to the brain Appetite is controlled by Cortex of brain Hypothalamus Thalamus Stomach In human body the number of spinal nerves is 12 pairs 31 pairs 31 33