♠ Motor division issues directives out to muscle or glandular tissue 中枢/外周神经功能分类. ♠ Sensory division brings information regarding the int. or ext. environment into the CNS ♠ Motor division issues directives out to muscle or glandular tissue ♣Somatic nervous system services skeletal muscle ♣ Autonomic nervous system services smooth &cardiac muscle: ♦ Sympathetic nervous system is responsible for the "fight-or-flight"response; ♦ Parasympathetic nervous system is responsible for the "rest-anddigest"response

Divisions of the Nervous System Central Nervous System Peripheral Nervous System nerves cranial nerves spinal nerves

The Spinal Nerves 1. General Description 31 Pairs of Spinal Nerves Cervical Nerves : 8 pairs Thoracic Nerves : 12 pairs Lumbar Nerves : 5 pairs Sacral Nerves : 5 pairs Coccygeal Nerves : 1 pair

Four types of fibers in spinal Nerves Two Roots : anterior root--motor fibers; posterior root--sensory fibers Somatic efferent[motor]fibers; Visceral efferent [motor] fibers Four branches of a spinal nerves Anterior branch ; posterior branch Meningeal branch; communicating branches

Four plexuses Cervical plexus颈丛 Brachial plexus臂丛 Lumbar plexus腰丛 Sacral plexus骶丛 The thoracic nerves are separated from each other.

Cervical Plexus The cervical plexus is formed by ventral rami of C1-C4 Most branches are cutaneous nerves of the neck, ear, back of head, and shoulders The most important nerve of this plexus is the phrenic nerve The phrenic nerve is the major motor and sensory nerve of the diaphragm

The cervical plexus is formed from ventral rami of the first 4 cervical nerves, buried deep in neck below the sternocleidomastoid muscle Cervical plexus produces mostly cutaneous nerves serving skin of the ears,neck & shoulder Also forms phrenic nerve serving the diaphragm

The cervical Plexus The Formation of the Cervical Plexus: The anterior branches of the 1st to 4th cervical nerves (C1~4)

Brachial Plexus Formed by C5-C8 and T1 (C4 and T2 may also contribute to this plexus) It gives rise to the nerves that innervate the upper limb Axillary – innervates the deltoid and teres minor Median – branches to most of the flexor muscles of arm Ulnar – supplies the flexor carpi ulnaris and part of the flexor digitorum profundus Radial – innervates essentially all extensor muscles

The Brachial Plexus (scalene fissure, axilla) formation: root(C5 – T1)

Radial Nerve

The Anterior Branches of the Thoracic Nerves ——Intercostal and subcostal nerve

The segmental distribution of the anterior branches of the thoracic nerves T2: the sternal angle T8: the costal arch T4: the nipple T10: the umbilicus T6: the xiphoid process T12: the anterior superior iliac spin

The Lumbar Plexus The formation of the lumbar plexus: T12 (part)+L1~3+L4 (part)

The branches of the lumbar plexus The iliohypogastric nerve The ilioinguinal nerve The lateral femoral cutaneous nerve The femoral nerve The obturator nerve The genitofemoral nerve

The Sacral Plexus The formation of the sacral plexus The lumbosacral trunk(L4~5)+S1~5+Co

The branches of the sacral plexus The superior gluteal n. The inferior gluteal n. The pudendal n. The posterior femoral cutaneous n. The sciatic nerve The branches of the sacral plexus

The sciatic nerve The tibial nerve The common peroneal nerve (Poplited fossa) The tibial nerve (hook-like foot) The common peroneal nerve (talipes equinovarus) The superficial peroneal The deep peroneal nerve

Autonomic System Two divisions: Control involuntary functions Sympathetic nerve交感神经 Parasympatheitic nerve副交感神经 Control involuntary functions heartbeat blood pressure respiration perspiration digestion Can be influenced by thought and emotion

Sympathetic “ Fight or flight” response Release adrenaline and noradrenaline Increases heart rate and blood pressure Increases blood flow to skeletal muscles Inhibits digestive functions CENTRAL NERVOUS SYSTEM Brain Spinal cord SYMPATHETIC Dilates pupil Stimulates salivation Relaxes bronchi Accelerates heartbeat Inhibits activity Stimulates glucose Secretion of adrenaline, nonadrenaline Relaxes bladder Stimulates ejaculation in male Sympathetic ganglia Salivary glands Lungs Heart Stomach Pancreas Liver Adrenal gland Kidney keywords: sympathetic nervous system; fighlt or flight response

Parasympathetic “ Rest and digest ” system Calms body to conserve and maintain energy Lowers heartbeat, breathing rate, blood pressure CENTRAL NERVOUS SYSTEM Brain PARASYMPATHETIC Spinal cord Stimulates salivation Constricts bronchi Slows heartbeat Stimulates activity Contracts bladder Stimulates erection of sex organs Stimulates gallbladder Gallbladder Contracts pupil key words: parasympathetic nervous system; rest and digest system

Summary of autonomic differences Autonomic nervous system controls physiological arousal Sympathetic division (arousing) Parasympathetic division (calming) Pupils dilate EYES Pupils contract Decreases SALVATION Increases Perspires SKIN Dries Increases RESPERATION Decreases Accelerates HEART Slows Inhibits DIGESTION Activates Secrete stress hormones ADRENAL GLANDS Decrease secretion of stress hormones key words: sympathetic nervous system; parasympathetic nervous system

Sympathetic Division Myelinated preganglionic exit spinal cord in ventral roots at T1 to L2[L3] levels. Travel to ganglia at different levels to synapse with postganglionic neurons. Divergence: Preganglionic fibers branch to synapse with numerous postganglionic neurons.

Sympathetic Division Axons of postganglionic neurons are unmyelinated to the effector organ. Preganglionic neuron is short. Post-ganglionic neuron is long.

Parasympathetic Division Preganglionic fibers originate in midbrain, medulla, and pons; and in the 2-4 sacral levels of the spinal cord. Preganglionic fibers synapse in ganglia located next to or within organs innervated. Do not travel within spinal nerves. Do not innervate blood vessels, sweat glands,and arrector pili muscles.

Parasympathetic Division 4 of 12 pairs of cranial nerves contain preganglionic parasympathetic fibers. Preganglionic fibers are long, postganglionic fibers are short. Vagus: Innervate heart, lungs esophagus, stomach, pancreas, liver, small intestine and upper half of the large intestine.

Parasympathetic Division Preganglionic fibers from the sacral level innervate the lower half of large intestine, the rectum, urinary and reproductive systems.