13_LectureOutline

13_LectureOutline - An Introduction Spinal Reflexes Rapid,...

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Unformatted text preview: An Introduction Spinal Reflexes Rapid, automatic nerve responses triggered by specific stimuli * Controlled by spinal cord alone, not the brain Spinal Cord * Gross Anatomy of the Spinal Cord * About 18 inches (45 cm) long * 1/2 inch (14 mm) wide * Ends between vertebrae L 1 and L 2 * Bilateral symmetry * Grooves divide the spinal cord into left and right * Posterior median sulcus: on posterior side * Anterior median fissure: deeper groove on anterior side * Enlargements of the Spinal Cord Caused by Amount of gray matter in segment * Involvement with sensory and motor nerves of limbs Cervical enlargement Nerves of shoulders and upper limbs Lumbar enlargement Nerves of pelvis and lower limbs * Gross Anatomy of the Spinal Cord * The Distal End * Conus medullaris: * thin, conical spinal cord below lumbar enlargement * Filum terminale: * thin thread of fibrous tissue at end of conus medullaris * attaches to coccygeal ligament * Cauda equina: * nerve roots extending below conus medullaris 31 Spinal Cord Segments Based on vertebrae where spinal nerves originate * Positions of spinal segment and vertebrae change with age Cervical nerves: are named for inferior vertebra All other nerves: are named for superior vertebra * Roots * Two branches of spinal nerves * Ventral root: * contains axons of motor neurons * Dorsal root: * contains axons of sensory neurons * Dorsal root ganglia * contain cell bodies of sensory neurons The Spinal Nerve Each side of spine Dorsal and ventral roots join * To form a spinal nerve Mixed Nerves Carry both afferent (sensory) and efferent (motor) fibers * The Spinal Meninges * Specialized membranes isolate spinal cord from surroundings * Functions of the spinal meninges include * Protect spinal cord * Carry blood supply * Continuous with cranial meninges * Meningitis: * Viral or bacterial infection of meninges * The Three Meningeal Layers * Dura mater * Outer layer of spinal cord * Arachnoid mater * Middle meningeal layer * Pia mater * Inner meningeal layer * The Dura Mater * Tough and fibrous * Cranially * Fuses with periosteum of occipital bone * Is continuous with cranial dura mater * Caudally * Tapers to dense cord of collagen fibers * Joins filum terminale in coccygeal ligament * The Epidural Space * Between spinal dura mater and walls of vertebral canal * Contains loose connective and adipose tissue * Anesthetic injection site * The Arachnoid Mater Middle meningeal layer * Arachnoid membrane Simple squamous epithelia * Covers arachnoid mater * The Interlayer Spaces of Arachnoid Mater * Subdural space * Between arachnoid mater and dura mater * Subarachnoid space * Between arachnoid mater and pia mater * Contains collagen/elastin fiber network (arachnoid trabeculae) * Filled with cerebrospinal fluid (CSF) * Cerebrospinal Fluid (CSF) * Carries dissolved gases, nutrients, and wastes * Spinal tap: withdraws CSF * The Pia Mater Is the innermost meningeal layer...
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13_LectureOutline - An Introduction Spinal Reflexes Rapid,...

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