Lecture 12b - Spinal Cord

Lecture 12b - Spinal Cord - Overview Chapter 12b Spinal...

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1 Chapter 12b Spinal Cord Overview • Spinal cord gross anatomy • Spinal meninges • Sectional anatomy • Sensory pathways • Motor pathways • Spinal cord pathologies The Adult Spinal Cord • About 18 inches (45 cm) long • 1/2 inch (14 mm) wide • CNS tissue ends between vertebrae L 1 and L 2 – At birth, cord and vertebrae are about the same size but cord stops elongating at around age 4 • 31 segments (31 pairs of spinal nerves) • Each pair of nerves exits the vertebral column at the level it initially lined up with at birth Figure 13-2 Gross Anatomy of the Spinal Cord Distal End • Conus medullaris : – thin, conical end of the spinal cord • Cauda equina : – nerve roots extending below conus medullaris • Filum terminale : – thin thread of fibrous tissue at end of conus medullaris – attaches to coccygeal ligament Size of cord segments • The more superior, the more white matter. Why do you think this is? • Grey matter larger in cervical and lumbar regions. Why is this?
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2 31 Spinal Cord Segments • C8, T12, L5, S5, Co1 • Based on vertebrae where spinal nerves originate • Positions of spinal segment and vertebrae change with age • Spinal nerves originally line up with their exit point from the cord. • Even after the vertebral column grows much longer, each pair of spinal nerves still exits at its original location, now several segments away Roots • 2 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 – Pseudounipolar neurons - weird Dorsal Root Ganglia Dendrites Spinal Meninges • Specialized membranes isolate spinal cord from surroundings • Spinal meninges : – protect spinal cord – carry blood supply – continuous with cranial meninges Figure 13–3 Spinal Meninges Dura mater : outer layer Arachnoid mater : middle layer Pia mater : inner layer The Spinal Dura Mater • Are tough and fibrous • Cranially: – fuses with periosteum of occipital bone – continuous with cranial dura mater • Caudally: – tapers to dense cord of collagen fibers – joins filum terminale in coccygeal ligament (for longitudinal stability)
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3 The Epidural Space • Between spinal dura mater and walls of vertebral canal (above the dura) • No such space in the brain • Contains loose connective and adipose tissue • Anesthetic injection site Inter-Layer Spaces – just like in the brain • Subdural space : – between arachnoid mater and dura mater • Subarachnoid space : – between arachnoid mater and pia mater – filled with cerebrospinal fluid (CSF) • Spinal Tap withdraws CSF from inferior lumbar region (below conus medularis) for diagnostic purposes. • Where do they get the CSF?
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This note was uploaded on 01/16/2012 for the course BI 200 taught by Professor Potter during the Fall '11 term at Montgomery College.

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Lecture 12b - Spinal Cord - Overview Chapter 12b Spinal...

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