Tymaa Al-zaben & Amin Al-ajalouni

Transcription

1 Done by: Tymaa Al-zaben & Amin Al-ajalouni

2 ** Hello SERTONIN! SLIDE 3 note:: the slide included within the sheet but make sure back to slide for pictures The Autonomic Nervous System Function : Regulate activity of smooth muscle, cardiac muscle & certain glands. Structures involved : 1- general visceral afferent neurons (GVA) 2- general visceral efferent neurons (GVE) 3-integration center within the brain "control center in hypothalamus and other system such as limbic system" Receives input from limbic system and other regions of the cerebrum. SLIDE4 Autonomic versus Somatic NS Somatic nervous system Afferent : consciously perceived sensations. Effectors : excitation of skeletal muscle. Efferent : one neuron from CNS, cell body either in anterior horn of spinal cord in spinal nerve OR motor nuclei of cranial nerve axon exit directly toward effectors organ( Skeletal muscles). Autonomic nervous system Afferent : unconsciously perceived visceral sensations. Effectors : involuntary inhibition or excitation of smooth muscle, cardiac muscle or glandular secretion. Efferent : two neurons needed to connect CNS to organ.

3 preganglionic "cell body in CNS" and its axon exit toward target which is postganglionic neurons and its axon exit toward effectors. SLIDE 5 Autonomic versus Somatic NS Notice that the ANS pathway is a 2 neuron pathway while the Somatic NS only contains one neuron. ** The major Neurotransmitter is ACh, exception in sympathetic-post ganglionic neuron which is Epinephrine. SLIDE 6 Comparison of Somatic and Autonomic Nervous Systems please back to slide to read the table SLIDE 7 Basic Anatomy of Motor ANS Preganglionic neuron cell body inside brain or spinal cord axon is myelinated type B fiber that extends to autonomic ganglion neurotransmitter :ACh Postganglionic neuron cell body lies outside the CNS in an autonomic ganglion axon is unmyelinated type C fiber that terminates in a visceral effectors neurotransmitter :ACh+ epinephrine SLIDE 8 Divisions of the ANS

4 2 major divisions 1-Sympathetic (thoracolumbar) division *preganglionic cell bodies in thoracic and first 2 lumbar segments of spinal cord "anteriomedial cell column in lateral horn of spinal cord" and it is the only area where the preganglion of sympathetic is present. 2-Parasympathetic (craniosacral) division ** two part 1- cranial part 2- spinal part ((sacral region)) preganglionic cell bodies in nuclei of 4 cranial nerves and the sacral spinal cord (S2-S4) and same area of sympathetic "anteriolateral horn" exit with spinal nerve. ## Both sympathetic &parasympathetic Dual((double )) innervated different organ "viscera " : we mean in dual innervations ; same organ innervated by sympathetic and parasympathetic^^opposite action ^^. -one speeds up organ and one slows down organ *Sympathetic NS increases heart rate * Parasympathetic NS decreases heart rate SLIDE 9 Sympathetic Division

5 Autonomic ganglion Sympathetic parasympathetic application to that... preganglion shorter longer post ganglion Longer -Near to CNS &direct parallel to vertebral column Shorter -connection near the wall of organ its self *sympathetic innervate more structures and more organs than parasympathetic. *so parasympathetic is more specific in action than sympathetic that is why parasympathetic for normal physiological situation and opposite to it sympathetic in emergence situation.. A single sympathetic preganglionic fiber has many axon collaterals and may synapse with 20 or more postganglionic neurons. The postganglionic axons typically terminate in several visceral effectors and therefore the effects of sympathetic stimulation are more widespread than the effects of parasympathetic stimulation. SLIDE 10 Structure of the Sympathetic Division

6 Thoracolumbar division Preganglionic neurons originate from the thoracic and lumbar levels of the spinal cord (T1 L2) IN The lateral horn (intermediolateral column (IML)) Sympathetic ganglia: post ganglion present outside CNS in autonomic ganglia "sympathetic ganglia" **types of sympathetic ganglion: 1) Paravertebral ganglia: we are talk about Sympathetic trunk (vertebral chain) ganglia which direct parallel to vertebral column. 2)Prevertebral (collateral) ganglia: present in abdominopelvic region, or organs innervated by sympathetic NS in abdomen &pelvis where the post ganglion present there. example : 'note that the name of them referral to the name of major branches of abdomen aorta'. celiac, superior mesenteric, inferior mesenteric, aorticorenal **SO preganglionic in spinal cord 'thoracic region' and postganglionic either in sympathetic trunk or preverbal column. SLIDE 11 Pathway from Spinal Cord to Sympathetic Trunk Ganglia: Preganglionic axons anterior root of a spinal nerve white ramus sympathetic trunk ganglion.

7 **cell body of Preganglion in lateral horn of S.C exit S.C with ventral root of spinal nerve & unit with ventral root.. **spinal nerve exit by intervertebral foramen, outside vertebral column gives branch: Dorsal,ventral, rami communicant(white +gray) White rami communicantes transmitted fiber of Preganglion neuron outside S.C toward sympathetic trunk. White rami communicantes: structures containing sympathetic preganglionic axons that connect the anterior ramus of the spinal nerve with the ganglia of the sympathetic trunk. SLIDE 12 Fate of Preganglionic Neurons in Sympathetic Trunk What will happen to pre ganglion fiber?? Options : 1. Synapse in the post sympathetic ganglion of sympathetic trunk at the same level (at level of entry). 2. Ascend up or descend in the sympathetic trunk and then synapse with postganglionic neouron in ganglia (above) or (below).. to serve structure above\below thoracic ; we know that the pre ganglion of sympathetic present only in thoracic and upper lumber so we need to provide another structure..

8 3. Continue, without synapsing, through the sympathetic trunk ganglion to end at a prevertebral ganglion(anterior to abdomen aorta) and synapse with post in it. Innervating viscera in the abdominopelvic cavity exit Via abdominopelvic splanchnic nerves ' above diaphragm ' 4. Pass through the sympathetic trunk ganglion and a prevertebral ganglion and then to the adrenal medulla 'the cells of medulla serve as post ganglionic'. SLIDE 13 Organization of Sympathetic Trunk Ganglia Two sympathetic trunks along the vertebral column(both side) Each sympathetic trunk ganglia has: 3 cervical(sup,mid,inf),11or12 thoracic, 4 or 5 lumbar, 4 or 5 pelvic and both trunks end caudally in one joint بلتقوا مع بعض بالنهاية وبشكلوا impar) ganglion (ganglion Postganglionic neurons from the superior cervical ganglion head and heart. the middle cervical ganglion and the inferior cervical ganglion heart. Thoracic sympathetic trunk heart(upper part of thoracic), lungs, and bronchi. so keep in your minde HEAD== Upper Cervical HEART==Mid & Inf Cervical & Upper part of Thoracic

9 SLIDE 14 Pathways from Sympathetic Trunk Ganglia to Visceral Effects The axons for the sympathetic nervous system are 4: 1-spinal 2-cephalic periarterial 3-sympathetic nerves 4-splanchnic nerves The territory of the sympathetic nervous system: All viscera Blood vessels Erector pili muscles Which means that the sympathetic nervous system needs to reach all over the body (somatic regions) *Unlike the parasympathetic which only reaches the viscera Which also means that the easiest way to reach all somatic areas is by the spinal nerves So the spinal nerves will carry with their (somatic afferents and efferents)post ganglionic sympathetic fibers The cephalic periarterial nerves will go the head and neck regions The sympathetic nerves are considered direct postganglionic nerves from the sympathetic trunk that will go to the viscera of thoracic or cervical region And the splanchnic like we said contain preganglionic fibers that will go toward the prevertebral ganglion. SLIDE 15 THE SPINAL NERVES:

10 Gray ramus: Axons of some postganglionic neurons leave the sympathetic trunk by entering a short pathway called a gray ramus and merge with the anterior ramus of a spinal nerve. Blood vessels (vasomotion), arrector mm. (pilomotion), and sweat glands (sudomotion).. Gray rami communicantes: structures containing sympathetic postganglionic axons that connect the ganglia of the sympathetic trunk to spinal nerves. Like we already mentioned that the spinal nerves intermediolateral cell columen will give preganglionic sympathetic fibers which will go to the spinal never then to the sympathetic trunk via the white communicants, after it reaches the trunk it will synapse with the ganglia there and the postganglionic fibers from the ganglia will go back again to the spinal nerves via the gray communicants, which will then innervate all the somatic regions via the spinal nerves. SLIDE 16 CEPHALIC PERIARTERIAL NERVES: Some sympathetic preganglionicneurons that enter the sympathetic trunk ascend to the superior cervical ganglion where they synapse with postganglionic neurons Some of these leave the sympathetic trunk by forming cephalic arterial nerves. Serve visceral effectors in the skin of the face and head and iris (dilator) Like we know we don t have spinal nerves in the head region, we only have cranial nerves And we also don t have white or gray communicants in head region So how will we get sympathetic innervation to the head region?

11 The superior cervical ganglion will receive efferent sympathetic fibers thro white communicants and it will synapse in the ganglia, then the postganglionic fibers will leave as the cephalic periarterial (around blood vessesl) (they will use the arteries like the carotid and form plexuses around them) nerves after they become close with their target they will jump from being close to arteries (periarterial) to the cranial nerves, ex:deep petrosal nerves which was considered cephalic periarterial nerve until it reached pterygoid canal and joined the great petrosal and formed the nerve of pterygoid canal SLIDE 17 THE SYMPATHETIC NERVES: Some axons of the postganglionic neurons leave the trunk by forming sympathetic nerves (Cardiopulmonary splanchnic nerves) Innervate the heart and lungs. Serves all viscera above diaphragm tqreebn (in thoracic region and cervical) (like heart lungs.) It is formed in this pattern Preganglionic sympathetic fibers going to the sympathetic trunk via white communicants then synapsing with any ganglia in the trunk either at same level or not, then those postganglionic fibers will leave as the sympathetic nerves A student asked: how will the superior cervical innervate the heart?? Doctors answer: 3adi it descends down to the heart but before reaching the heart it forms a plexus (cardiac plexus) SLIDE 18 SPLANCHNIC NERVES:

12 # Some sympathetic preganglionic axons pass through the sympathetic trunk without terminating in it. Beyond the trunk they form nerves called splanchnic nerves which extend to prevertebral ganglia 1. T5 T9 or T10 Greater splanchnic nerve 2. T10 T11 Lesser splanchnic nerve 3. T12 least splanchnic nerve 4. L1 L4 Lumbar splanchnic nerve They leave the sympathetic trunk as preganglionic fibers!!! Which means they don t synapse in the sympathetic ganglias (important to remember) and they will go toward the prevertebral ganglia They are from t5-t12 but sometimes we can say we have lumbar splanchnic nerves too We have greater splanchnic nerves, lesser splanchnic never, least splanchnic nerves which all originate above the diaphragm and penetrate the diaphragm down to the abdomen mainly from the cruras of diaphragm so they can reach the prevertebral ganglia SLIDE 20 Splanchnic Nerves to the Adrenal Medulla Some sympathetic preganglionic axons pass, without synapsing, through the smpathetic trunk, greater splanchnic nerves and celiac ganglion into the adrenl medulla (modified sympathetic ganglia). Release hormones into blood 80% epinephrine, 20% norepinephrine.

13 But also put in mind that not all splanchnic nerves will terminate in the prevertebral ganglia, some of them may continue to the adrenal glands (medulla) and synapse there to help secrete epinephrine and norepinephrine SLIDE 19 THE PREVERTEBRAL GANGLIA: We have 4 ganglias : celiac, aorticorenal, superior mesenteric, inferior mesenteric All of theseganglias receive preganglionic fibers from splanchnic nerves then synapse and give postganglionic fibers to the abdominopelvic organs Note: all viscera is supplied by what we call plexuses which contains sympathetic and parasympathetic fibers like (thoracic, cranial) SLIDE 22 AFFERENT SYMPATHETIC FIBERS: Viscera sympathetic ganglion white rami communicants spinal nerve dorsal root ganglion spinal cord Theres a lil different between somatic and autonomic afferents, the autonomic afferents perception is lower than somatic perception, less sensitivity, less in number, and less receptors. Mainly they are end nerves neurons and they carry a lot of modalities These afferent fibers will go back the same way they came as simple as that but when they reach the nerve level they will go to the dorsal root ganglia of spinal cord and this is why we have what is called referral pain when we have visceral damage because of the meeting between visceral afferents and somatic afferents in the dorsal root ganglia

14 So the visceral referral pain depends on the entrance into the spinal cord so if a sympathetic afferent of an organ entered at the level of t3-t5 the referral pain will be mostly in dermatomes innervated by t3-t5 SLIDE 21 ORGANS INNERVATED BY SYMPATHETIC SYSTEM: Structures innervated by each spinal nerve sweat glands, arrector pili mm., blood vessels to skin & skeletal mm. Thoracic & cranial plexuses supply: heart, lungs,esophagus & thoracic blood vessels. plexus around carotid artery to head structures. Splanchnic nerves to prevertebral ganglia supply: GI tract from stomach to rectum, urinary & reproductive organs. Sorry for any mistakes "Difficult Roads often leads to beautiful destinations" THE END <3