Chapter 13 - The Spinal Cord

Chapter 13 - The Spinal Cord - Chapter 13 - The Spinal...

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Chapter 13 - The Spinal Cord, Spinal Nerves, and Spinal Reflexes Spinal Reflexes 0. Rapid, automatic nerve responses triggered by specific stimuli 1. Controlled by spinal cord alone, not the brain Spinal Cord - Gross Anatomy 0. About 18 inches (45 cm) long and ½ inch (14 mm) wide; ends between vertebrae L 1 and L 2 1. Bilateral symmetry 0. Grooves divide the spinal cord into left and right 1. Posterior median sulcus: on posterior side 2. Anterior median fissure: deeper groove on anterior side Enlargements of the Spinal Cord are caused by Amount of gray matter in segment & involvement with sensory and motor nerves of limbs 2. Cervical enlargement - Nerves of shoulders and upper limbs 3. Lumbar enlargement - Nerves of pelvis and lower limbs The Distal End 3. Conus medullaris: thin, conical spinal cord below lumbar enlargement 4. Filum terminale: thin thread of fibrous tissue at end of conus medullaris; attaches to coccygeal ligament 5. Cauda equina: nerve roots extending below conus medullaris 31 Spinal Cord Segments 4. Based on vertebrae where spinal nerves originate 5. Positions of spinal segment and vertebrae change with age 2. Cervical nerves: are named for inferior vertebra 3. All other nerves: are named for superior vertebra 6. Ventral root: contains axons of motor neurons contains axons of sensory neurons 4. Dorsal root ganglia contain cell bodies of sensory neurons The Spinal Nerve on each side of spine the dorsal and ventral roots join to form a spinal nerve 6. Mixed Nerves carry both afferent (sensory) and efferent (motor) fibers The Spinal Meninges are specialized membranes isolate spinal cord from surroundings 5. Functions of the spinal meninges include 8. Protect spinal cord 9. Carry blood supply 10. Continuous with cranial meninges 6. Meningitis: viral or bacterial infection of meninges TheThree Meningeal Layers 1. The Dura Mater - Outer layer of spinal cord that is tough and fibrous 7. Cranially - fuses with periosteum of occipital bone & is continuous with cranial dura mater 8. Caudally - tapers to dense cord of collagen fibers & joins filum terminale in coccygeal ligament 9. The Epidural Space - between spinal dura mater and walls of vertebral canal 11. Contains loose connective and adipose tissue 12. Anesthetic injection site 2. The Arachnoid Mater - Middle meningeal layer 7. Arachnoid membrane - simple squamous epithelia that covers arachnoid mater The Interlayer Spaces of Arachnoid Mater 10. Subdural space - between arachnoid mater and dura mater 11. Subarachnoid space - between arachnoid mater and pia mater 1. Contains collagen/elastin fiber network (arachnoid trabeculae) 2. Filled with cerebrospinal fluid (CSF) Cerebrospinal Fluid (CSF) - carries dissolved gases, nutrients & wastes; Spinal tap withdraws CSF 1
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c. The Pia Mater - is the innermost meningeal layer; a mesh of collagen & elastic fibers bound to underlying neural tissue Gray Matter and White Matter - Sectional Anatomy of the Spinal Cord i.
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Chapter 13 - The Spinal Cord - Chapter 13 - The Spinal...

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