autonomic nervous system dr richard tunstall warwick medical school gem 2013

Download Autonomic Nervous System Dr Richard Tunstall Warwick Medical School GEM 2013

Post on 14-Dec-2015

212 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Slide 1

Autonomic Nervous System Dr Richard Tunstall Warwick Medical School GEM 2013 Slide 2 Objectives State and demonstrate the regions of the spinal cord / the brainstem nuclei and the specific spinal and cranial nerves involved sympathetic and parasympathetic nerve outflow from the central nervous system. Explain the location and structure of the sympathetic chain, and outline the range of patterns of synapse of pre- and post ganglionic sympathetic fibres Outline the potential causes and consequences of a loss of sympathetic supply to a region/structure (this could be an intentional or unintentional loss) Describe the route of travel of parasympathetic nerves (with cranial nerves) & name and explain the position of the ganglion at which the pre- and post- ganglionic fibres synapse Explain the functions of the parasympathetic nerves such that you could explain the consequence of an injury to a given nerve, or deduce the location of an injury from a given set of signs/symptoms Describe the receptors and neurotransmitters of the peripheral nervous system (somatic and autonomic) Describe the functions of the autonomic nervous system and explain the differing effects of the receptor types within the sympathetic and parasympathetic nervous systems R G Tunstall 2013 Slide 3 Overview Parasympathetic nervous system Slows heart rate (no effect on force) Relaxes blood vessels Speeds up GI transit Relaxes sphincters Increases salivation Bronchoconstricts Constricts pupil (miosis) Erection Sympathetic nervous system Raises heart rate Increases force of contraction Constricts most blood vessels Slows GI transit Constricts sphincters Bronchodilates Increase sweating Dilates pupil (mydriasis) Secretion of seminal fluid/movement of sperm R G Tunstall 2013 Slide 4 Neurons Dendrites: receptive projections sensitive to neurotransmitter input Soma (cell body): metabolic centre Axon: one-way rapid communication between cell body and axon terminals Axon Terminals: form connections with other neurons/effector tissue via synapses Neurons are the functional building blocks of the nervous system R G Tunstall 2013 AT S S S S Slide 5 Nervous System Central nervous system Brain, spinal cord, retina & CNII Peripheral nervous system Spinal & cranial nerves (all except CNII) Autonomic nervous system (sympathetic & parasympathetic) Somatic sensory and motor nerves The nervous system consists of central and peripheral parts R G Tunstall 2013 Slide 6 Motor (Efferent) Sensory (Afferent) Somatic motor (Skeletal muscle) Visceral/Autonomic motor (Organs & vessel) Somatic sensory (Sensations from somatic tissues) Visceral sensory (Sensations from organs & vessels) Nervous System Outflows & Inflows Spinal nerve Mixed nerve containing motor, & sensory neurons Some contain autonomic neurons Branchio-motor (Pharyngeal arch muscle) R G Tunstall 2013 Special Visceral sensory (Taste) Slide 7 Autonomic Nervous System Autonomic neurons are classified as pre- and post-ganglionic Brainstem nucleus / Cell body in lateral horn Peripheral ganglion Target Preganglionic Postganglionic These nuclei are controlled by descending reticospinal tract neurons. The latter neurons are separate to the pre/post ganglionic classification R G Tunstall 2013 Lateral horn Autonomic (only seen T1-L2 & S2-4) Slide 8 T1 spinal nerve L2 spinal nerve Sympathetic Nervous System Neurons controlling lateral horn cells (or autonomic brainstem nuclei) arise in the hypothalmus Sympathetic nerves exit CNS with T1 - L2 spinal nerves THERE ARE NO OTHER EXIT POINTS Sympathetic chain extends to tip of sacrum Sympathetic chain extends up to near the skull base Damage to the spinal cord at VERTEBRAL LEVEL L1 should not affect sympathetic innervation but will affect pelvic parasympathetic nerves R G Tunstall 2013 Slide 9 Autonomic Nervous System Sympathetic nerves emerge from the CNS only with spinal nerves T1-L2 R G Tunstall 2013 Sympathetic chain Runs on lateral sides of vertebral bodies throughout all vertebral column regions Slide 10 Rami communicans White = preganglionic sympathetic neurons passing into chain Grey = postganglionic sympathetic neurons passing from chain into spinal nerve Sympathetic chain Sympathetic ganglia Dont forget nerves such as the thoracic & cardiac splanchnic nerves emerge from the sympathetic chain Sympathetic Nervous System The sympathetic chain communicates with spinal nerves via rami communicans R G Tunstall 2013 Slide 11 Sympathetic Nervous System Spinal nerve Dorsal root ganglion Formed by the cell bodies of sensory neurons Ventral ramus Dorsal ramus White rami communicans - seen between T1-L2 only Preganglionic sympathetic neurons passing into chain Grey rami communicans Postganglionic sympathetic neurons passing back into spinal nerve Sympathetic chain ganglion Grey rami communicans only No white ramus communicans seen before spinal nerve T1 or after L2 The sympathetic chain communicates with spinal nerves via rami communicans R G Tunstall 2013 Slide 12 T1 L2 a) Reticulospinal tract neurons originate in brainstem/hypothalamus b) Descend to T1 & synapse with preganglionic neuron in lateral horn c) Exit cord with T1 spinal nerve d) Travel to sympathetic chain e) Run up chain to cervical ganglia & synapse with postganglionic neuron f) Postganglionic neurons enter head as plexus around internal carotid artery g) Supply face via external carotid artery. Sympathetic Supply to the Head Brainstem or spinal cord injury proximal to T1 cord level can affect sympathetic supply to head R G Tunstall 2013 Slide 13 Sympathetic Chain Ganglia in the Neck Superior cervical C1-4 Near skull base Middle cervical C5-6 Stellate C7-T1 Near lung apex There are normally x3 sympathetic chain ganglia in the neck R G Tunstall 2013 Causes of damage Pancoast tumour Tumour of skull base Lyphadenopathy Iatrogenic Trauma Slide 14 CN VII Sympathetic neurons form a plexus around the internal carotid artery which join parasympathetic nerves. Distributed with arterial branches Run to pterygo-palatine ganglion from which they are distributed Distributed with branches of CN V This is the superior cervical ganglion in the neck Sympathetic Supply to the Head Forms deep petrosal nerve which joins parasympathetic greater petrosal nerve Sympathetic neurons are distributed in the head with cranial nerves and arteries R G Tunstall 2013 Slide 15 Sympathetic Supply to the Head Loss of sympathetic supply to the head leads to Horners syndrome R G Tunstall 2013 Slide 16 Sympathetic Supply to the Head Loss of sympathetic supply to the head leads to Horners syndrome Pupil constriction (miosis) Vasodilation Ptosis Lack of sweating (anhydrosis) Emerg Med J doi:10.1136/emj.2009.081679 R G Tunstall 2013 Causes of damage Pancoast tumour Tumour of skull base Lyphadenopathy Iatrogenic Trauma Slide 17 Raynaud disease with tissue damage The sympathetic chain or sympathetic nerves can be cut/interrupted to treat certain diseases http://www.assh.org/Public/HandConditions/Pages/Cold-Hand.aspx Hyperhidrosis http://bestpractice.bmj.com/best-practice/monograph/856/resources/image/bp/1.html Sympathectomy Review the lecture video resources on Moodle R G Tunstall 2013 Slide 18 Sympathectomy R G Tunstall 2013 Sympathectomy for hyperhidrosis Slide 19 Sympathetic Nervous System Sympathetic Chain Ganglion Preganglionic Postganglionic Pre-aortic Ganglion Spinal nerves Visceral branches Arterial plexi Splanchnic nerves Fibres also travel up and down the chain Adrenal Medulla Lateral horn cells R G Tunstall 2013 Slide 20 Chromaffin cells of adrenal medulla release adrenaline (95%) into the blood Systemic release provides a mechanism for reaching cells with no sympathetic innervation Sympathetic Nervous System R G Tunstall 2013 Slide 21 Outflow with S2-4 spinal nerves Note: The S2-4 spinal nerves are formed at the L1/2 vertebral level Parasympathetic nuclei sit in the brainstem Outflow with CN III, VII, IX & X Parasympathetic Outflows Parasympathetic outflow from the CNS is with x4 cranial nerves and x3 spinal nerves R G Tunstall 2013 Slide 22 Autonomic Nervous System Parasympathetic outflow from the CNS is with x4 cranial nerves & 3 spinal nerves (conserve energy, bowel activity, urinate, defecate, erection) CN III CN VII CN IX CN X Pelvic splanchnic nerves From S2-4 Spinal nerves R G Tunstall 2013 Slide 23 Brainstem nucleus Peripheral ganglion Emerges with CN III, VII, IX or X Travels with CN V Target Preganglionic Postganglionic Parasympathetic Outflows Postganglionic parasympathetic fibres arising from cranial nerves III, VII, IX & X travel with branches of CN V R G Tunstall 2013 Slide 24 Parasympathetic nerves in the head are hitchhikers R G Tunstall 2013 Slide 25 Edinger Westphal Nucleus Superior salivatory nucleus Inferior salivatory nucleus Ciliary Ganglion Pterygopalatine Ganglion Submandibular Ganglion Otic Ganglion With CN III With CN Va With CN VII (via chorda tympani) With CN Vb With CN VII (via greater petrosal nerve) With CN Vc Eyes Pupil constriction Accommodation Mucous membranes Structures above the maxillary teeth e.g. palate, nasal cavity, sinuses, lacrimal gland Mucous membranes Structures below the the mandibular teeth e.g. sublingual, submandibular glands Parotid gland With CN IX With CN Vc NOTE: POSTGANGLIONIC FIBRES DISTRIBUTED WITH CN V BRANCHES Dorsal nucleus of vagus With CN X Organ-specific ganglia Parasympathetic Outflows (via lesser petrosal nerve) R G Tunstall 2013 Slide 26 Pterygopalatine Ganglion (CN VII) Parasympathetic Outflows Ciliary Ganglion (CN III) R G Tunstall 2013 Slide 27 Parasympathetic nerves to parotid gland (CN IX) Parasympathetic nerves to submandibular & sublingual glands (CN VII) CN V Parasympathetic Outflows Otic ganglion Submandibular ganglion Submandibular (CN VII supplied) & Otic Ganglia (CNIX supplied) R G Tunstall 2013 Slide 28 Pelvic splanchnic nerves Branch from S2