Spinal+Cord+Anatomy+Slides+2022+%281%29.pdf

Spinal Cord Summer 2022 [email protected] Objectives 1. Understand the structure of the central nervous system (CNS) and the peripheral nervous system (PNS) 2. Understand the functional divisions of the nervous systems, the somatic nervous system (SNS) and the autonomic nervous system (A...

Spinal Cord Summer 2022 [email protected] Objectives 1. Understand the structure of the central nervous system (CNS) and the peripheral nervous system (PNS) 2. Understand the functional divisions of the nervous systems, the somatic nervous system (SNS) and the autonomic nervous system (ANS) 3. Understand the basic embryological development of the spinal cord 4. Identify the cells types of the nervous system 5. Identify the structure of neurons and synapses 6. Explain the structure of the spinal cord, spinal peripheral nerves, meninges, dermatomes, myotomes, and vasculature specific to the area. Structural Organization of Nervous System Nervous System Central Nervous Peripheral Nervous System (CNS) System (PNS) Spinal Nerves Cranial Nerves Brain Spinal Cord (31 Pairs) (12 Pairs) Functional Organization From: http://academic.kellogg.edu/herbrandsonc/bio201_mckinley/Nervous%20System.htm  Somatic v. Autonomic SOMATIC NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM VOLUNTARY INVOLUNTARY Skeletal Muscle Smooth Muscle Sensation Glands Pain Internal Organs Pressure Touch Temperature Proprioception Development of Spinal Cord: Basic Embryology  Neurulation Process whereby the neural plate forms the neural tube. Lateral edges of the neural plate become elevated and form the neural folds; depressed mid- region becomes the neural groove. Gradually the neural folds approach each other in midline, where they fuse. Closure of the cranial neuropore @ day 25. Closure of the caudal neuropore @ day 28. Neurulation  Forebrain (prosencephalon) Diencephalon Midbrain (mesen cephalon) Midbrain ( mesencephalon) Hindbrain ( rhombencephalon) - - Metencephalon Medulla oblongata Neural tube with intraneural liquor space a b C d Schuenke, Atlas of Anatomy Vol. 3, 2nd Ed., Fig. 8.262 Ba-d, Illustrator: Karl Wesker/ Markus Voll, ©2016 Thieme Medical Publishers, Inc. All Rights Reserved. Neural Crest Cells Cells break away from epithelial layer of the developing dorsal neural tube and subsequently migrate as mesenchymal cells. Crest cells travel to many areas of the developing embryo and give rise to: Dorsal root ganglion ANS ganglia Ganglia to CN V, VII, IX, X Schwaan cells Meninges Pigment cells MS components of head Schwann Cell  Myelin Layers of lipid and protein Forms a sheath around some axons Increases the velocity of the impulse transmission from neuron to neuron  CNS v. PNS Neuron Structure CNS PNS Nucleus Ganglion Gray Matter Collection of nerve cell bodies Collection of Outside of CNS neuron cell bodies Tract Peripheral Nerve Collection of Nerve fibers White Matter Connect CNS with Collection of nerve peripheral structures fibers Spinal OR Cranial Nerves Connects Nuclei  Gray/White Matter From Schuenke et al. 2010. Thieme Atlas of Anatomy: Head and Neuroanatomy. Thieme, New York, p. 173  Gray/White Matter From Schuenke et al. 2010. Thieme Atlas of Anatomy: Head and Neuroanatomy. Thieme, New York, p. 173 Gray/White Matter Gray Matter and White Matter CNS From Blumenfeld, H. 2010. Neuroanatomy through Clinical Cases. 2nd Ed. Sinauer, Sunderland, MA. p. 21  SPINAL CORD Extension of the brainstem from the medulla Courses through the spine ending at L1-2 vertebral level Long and thin tube shaped bundle of nerve fibers Primary function is to transmit signals to and from the brain to peripheral structures Transverse Section of the Spinal Cord  From Blumenfeld, H. 2010. Neuroanatomy through Clinical Cases. 2nd Ed. Sinauer, Sunderland, MA. p. 227 Transverse Sections of Spinal Cord C5 T2 T8 L1 L2 S2 S3 From Netter FH. 2003 Atlas of Human Anatomy,3rd Ed. Icon Learning, Teterboro, NJ. Plate 158. Cross Sectional Variation Cervical Large and oval in appearance Large amt of white matter  From Netter FH. 2003 Atlas of Human Anatomy,3rd Ed. Icon Learning, Teterboro, NJ. Plate 158. WHY DO YOU THINK THIS IS? Small amt gray matter Descending (Motor) Tracts have not exited SC Cross Sectional Variation Thoracic Oval shaped Smaller than Cervical Have lateral horn  From Netter FH. 2003 Atlas of Human Anatomy,3rd Ed. Icon Learning, Teterboro, NJ. Plate 158. (Part of Autonomic NS) Cell bodies of sympathetic nervous system here Cross Sectional Variation Lumbar Round in shape and large Largest amount of gray matter Why?  From Netter FH. 2003 Atlas of Human Anatomy,3rd Ed. Icon Learning, Teterboro, NJ. Plate 158. Cross Sectional Variation Sacral Similar to lumbar level but smaller Most descending tracts have exited SC Many ascending tracts have not yet entered SC  From Netter FH. 2003 Atlas of Human Anatomy,3rd Ed. Icon Learning, Teterboro, NJ. Plate 158. Meninges: Three Membranous Layers Dura Mater Arachnoid Mater Pia Mater  From Blumenfeld, H. 2010. Neuroanatomy through Clinical Cases. 2nd Ed. Sinauer, Sunderland, MA. p. 322  From Blumenfeld, H. 2010. Neuroanatomy through Clinical Cases. 2nd Ed. Sinauer, Sunderland, MA. p. 322 Dura Mater Outermost Layer “Tough Mother” Thick and fibrous Separated from cord by epidural space Dura forms Spinal Dural Sac Continuous with dura that lines skull. Spinal nerves pierce this sac Ends at S1-2 Filum terminale anchors sac to coccyx Arachnoid Mater Middle Layer “Spider Mother” Delicate and Avascular Encloses Cerebrospinal Fluid (CSF) filled subarachnoid space between it and pia mater CSF Cushion for the cord Clear odorless fluid Low in protein and cellular content Pia Mater Innermost layer “Delicate Mother” Most delicate layer Closely follows the surface of the cord Directly covers spinal nerve roots and blood vessels Continues as filum terminale Dural Sac Filum terminale Pia from inferior most aspect of conus medullaris Pushes through dural sac taking arachnoid and dura mater with it From Tank PW. 2009. Grant’s Forms strong anchor on Dissector, 14th Ed. Wolters Kluwer, Baltimore, p. 16 posterior coccyx Denticulate ligaments Sheets of pia mater that anchor the cord to the dural sac Separates anterior (ventral) and posterior (dorsal) nerve roots Run longitudinally along the cord From Tank PW. 2009. Grant’s Dissector, 14th Ed. Wolters Kluwer, Baltimore, p. 17  From Lundy-Ekman; Neuroscience, 2007. Spinal Nerves 31 Pairs Cervical (8 pair) Exit Intervertebral foramina above named segment C8 exits above T1 vertebra Thoracic (12 Pair) Exit Below named segment Lumbar (5 pair) Exit Below named segment Sacral (5 Pair) Coccygeal (1 Pair)  From Blumenfeld, H. 2010. Neuroanatomy through Clinical Cases. 2nd Ed. Sinauer, Sunderland, MA. p. 320 Spinal Nerve Structure Spinal nerve Carries dorsal (afferent, sensory) and ventral (efferent, motor) from one spinal segment Somatic afferents Somatic efferents Visceral efferent Predictable patterns result Dorsal and ventral roots run in subarachnoid space covered in pia mater Each pierces dura mater separately taking arachnoid mater with it http://library.med.utah.edu/WebPath/HISTHTML/NEUR ANAT/CNS237A.html  Terminus of Spinal Cord Spinal Cord ends at L1/L2 level Conus Medullaris Cauda Equina Lumbar Cistern Enlargement of subarachnoid space to accommodate cauda equina Lumbar Cistern Dermatomes/Myotomes Area of skin innervated by a single spinal nerve Muscle receiving innervation from a single spinal level  Myotomes C3-5: Diaphragm L2: hip flexion C5: elbow flexion L3: knee extension C6: wrist extension L4: ankle dorsiflexion C7: elbow extension L5: toe extension C8: finger flexion S1: ankle plantarflexion T1: finger abduction S3-S5: bowel, bladder, sexual T1-T12: chest wall/abs organs Dermatomes/Myotomes Great deal of overlap among the levels Blending of spinal segments in the plexuses Cervical Brachial Lumbar Sacral Nerves and Vasculature C4 vertebra Nerves and Vasculature L2 vertebra From Haines DE. 2012. Neuroanatomy: An Atlas of Structures, Sections, and Systems, 8th Edition.