07.ANAT20006 Nervous system lecture 2.pdf

07.ANAT20006 Nervous system lecture 2.pdf - ANAT 20006...

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Unformatted text preview: ANAT 20006: Nervous system 2: Objectives • Organisation of the peripheral nervous system • Efferents, afferents and nerves • Somatic versus Autonomic divisions • Segmental innervation Associate Professor Stuart Mazzone Dept. Anatomy and Cell Biology E723 Medical Science Building [email protected] COPYRIGHT REGULATIONS 1969 Schedule 4 (regulation 4D) FORM OF NOTICE FOR PARAGRAPH 49 (7A) (c) OF THE COPYRIGHT ACT 1968 COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been provided to you pursuant to section 49 of the Copyright Act 1968 (the Act) for the purposes of research or study. The contents of the material may be subject to copyright protection under the Act. Further dealings by you with this material may be a copyright infringement. To determine whether such a communication would be an infringement, it is necessary to have regard to the criteria set out in Part 3, Division 3 of the Act. Axons in the periphery cluster together to form nerves collections of thousands of individual axons within a common external connective tissue sheath (epineurium). Within the nerve axons are sub-grouped into fascicles, surrounded by a perineurial sheath. nerve is something that caries the axon to the central nervus system out to the prefiray or to central nervois system From fig 9.2, Eizenberg et al. General Anatomy Axons in the periphery cluster together to form nerves collections of thousands of individual axons within a common external connective tissue sheath (epineurium). Within the nerve axons are sub-grouped into fascicles, surrounded by a perineurial sheath. CNS bundle of these axons in the preferal nervous sytem tract os the group of axons in the CNS Axons in the periphery cluster together to form nerves collections of thousands of individual axons within a common external connective tissue sheath (epineurium). Within the nerve axons are sub-grouped into fascicles, surrounded by a perineurial sheath. CNS Nerve Spinal Cranial SPINAL CORD AND SPINAL NERVES originate from spinal cord 31 pairs of spinal nerves: • 8 pairs of cervical nerves (C1-C8) • 12 pairs of thoracic nerves (T1 – T12) • 5 pairs of lumbar nerves (L1-L5) • 5 pairs of sacral nerves (S1-S5) • 1 pair of coccygeal nerves (Co1) • Peripheral nerve axons can be either efferent (motor) carrying signals from the CNS or afferent (sensory) carrying signals to the CNS. • Separate spinal roots connect efferent and afferent to the CNS. red sensory axon blue are motor axon no particular order but near the spinal cord it is ordered Figs 1.9 & 7.5. Bear et al. 2001 Efferent (blue) and afferent (red) axons segregate at the point just before they contact the CNS (spinal cord or brainstem): sensory axons join the CNS via a dorsal (posterior) root, motor axons join at a ventral (anterior) root. sensory on the dorsal side ventral has motor neurons ganglia contains the cell bodies of sensory motor neuron Efferent (blue) and afferent (red) axons segregate at the point just before they contact the CNS (spinal cord or brainstem): sensory axons join the CNS via a dorsal (posterior) root, motor axons join at a ventral (anterior) root. Cell bodies Spinal cord – Rami Ventral (anterior) and dorsal (posterior) rami raps around front of bdy Anterior tissues raps around back of body to suppy posterior tissue Posterior tissues Segmental Innervation each nerve has very specific innervation Segmental Innervation tome means slices A dermatome is an area of skin that is mainly supplied by a single spinal nerve A myotome is the group of muscles that a single spinal nerve innervates someone has injury at t2 the segment will let you kknow what area is effected Why is this important clinically? mixture of spinal innervation But note: A peripheral nerve is often comprised of multiple spinal nerves, ie several spinal segments contribute axons to a single peripheral nerve if u damage periferal nerve has more complicated deficete compared to a single spinal nurve Nerve plexus (Nerve braid”) NERVE PLEXUSES Cervical plexus (head, neck, diaphragm) Brachial plexus (upper limbs) innovates your arm Lumbosacral plexus Lumbar plexus (lower limbs) Sacral plexus (lower limbs) Cervical Plexus innovates the diophragm Brachial Plexus 5 nerves Lumbosacral Plexus inovates your leg CRANIAL NERVES Patrick J. Lynch, medical illustrator derivative work: CRANIAL NERVES primary organomic nerve SOMATIC VERSUS AUTONOMIC NERVOUS SYSTEM allows regulation of things we dont think about SOMATIC VERSUS AUTONOMIC NERVOUS SYSTEM collection of cell bodies in prepheral nervous system preganglionic neuron post ganglionic neuron parasympathetic ganglionn is further away from CNS Autonomic Nervous System - an effector system in the CNS and PNS mediating unconscious homeostatic control of organ and body physiology. Two main divisions: Sympathetic autonomic Parasympathetic autonomic From fig 9.12 & 13, Eizenberg et al. General Anatomy SYMPATHETIC OUTFLOW Somatic motor pathway Autonomic motor pathway– Preganglionic and postganglionic neurons sell body in the lateral horn From fig 9.46,47, Eizenberg et al. General Anatomy synapse of pre and post ganglionic neuron enters though white cummincating nerve and leaves by grey communicated nerve pre gang axon is myelinated PARASYMPATHETIC SACRAL NERVES within heart or gut SOMATIC VERSUS AUTONOMIC NERVOUS SYSTEM The autonomic and enteric divisions of the peripheral nervous system Blood vessels supplying muscle – not the muscle itself Enteric nervous system (autonomic neurons in the gut wall) is the third component of autonomic system. Sympathetic autonomic A huge number of neurons in the GIT wall forming circuits responsible for mixing, peristalsis and secretion. Parasympathetic autonomic From fig 9.12 & 13, Eizenberg et al. General Anatomy ...
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