Summary

This document provides comprehensive details about the spinal cord's gross features, its relationship to the vertebral column, segments, meninges (pia, arachnoid, dura), and associated spaces. It covers the structures, their functions and clinical relevance within the central nervous system.

Full Transcript

DR. WAGIH EL-HUSSEINY C.N.S. 1 The spinal cord  Gross features: ✓ It lies in the upper 2/3 of the vertebral canal. ✓ Its average of length is 45 cm & length of vertebral canal is 60 cm...

DR. WAGIH EL-HUSSEINY C.N.S. 1 The spinal cord  Gross features: ✓ It lies in the upper 2/3 of the vertebral canal. ✓ Its average of length is 45 cm & length of vertebral canal is 60 cm. ✓ It begins at the lower border of foramen magnum and continuous above with the medulla oblongata. ✓ It ends at the lower border of L1 and continues below with the filum terminale. ✓ Its lower end is expanded to form the conus medullaris. ✓ It is cylindrical and has 2 enlargements: Cervical enlargement: at C4 to T1 segments corresponding to the origin of brachial plexus. Lumbar enlargement: at L1 to S3 segments corresponding to lumbar and sacral plexuses.  Relations of the spinal cord to the vertebral column: ✓ At the 3rd month of fetal life it occupies the whole length of the vertebral canal. ✓ At birth it ends at level of L3. ✓ In adults, it ends at the level of L1.  Segments of the spinal cord: ✓ It has 31 segments arranged as 8 cevical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal. ✓ Each segment gives a pair of spinal nerves. 2 DR. WAGIH EL-HUSSEINY C.N.S. 1  Meninges of the spinal cord:  The spinal cord surrounded by 3 meninges which continuous at foramen magnum with their corresponding of the brain. ✓ From inside outwards these are pia matter, arachenoid matter and dura matter. 1. Pia matter: ✓ It’s the inner vascular layer. ✓ It surrounds the spinal cord and follows its fissures. ✓ It ends with the spinal cord at level of L1 vertebra. ✓ Its lower end forms the filum terminale. ✓ The denticulate ligament emerges from its right and left borders. 5 DR. WAGIH EL-HUSSEINY C.N.S. 1 o It’s a fibrous strand extending from the lower border of the pia matter. o It descends through the vertebral canal surrounded by roots of lower spinal nerves to form cauda equine. o It pierces the arachenoid and dura matters at level of S2 emerging from sacral hiatus to be attached to back of coccyx. o It helps in fixation of spinal cord. o It’s a toothed longitudinal ligament one on each side of the spinal cord. o It extends along whole length of the spinal cord. o It has 21 pointed processes which emerge from pia matter midway between the anterior and posterior nerve roots. o These processes pierce the arachenoid matter and become attached to the dura matter. o It helps in fixation of the spinal cord. 2. Arachenoid matter: ✓ It’s the middle layer of the 3 meninges. ✓ It’s thin, transparent and impermeable membrane. ✓ It ends at level of S2. 6 DR. WAGIH EL-HUSSEINY C.N.S. 1 3. Dura matter: ✓ It’s the outer layer. ✓ It’s tough, dense and strong. ✓ It ends as aeachenoid matter at level of S2.  Spaces between the meninges: 1. Sub-arachenoid space: It lies between the arachenoid and pia matters. It contains C.S.F. 2. Sub-dural space: It lies between the dura and arachenoid matters. It contains small amount of serous fluid to lubricate the movement of dura which is a tough membrane. 3. Extra-dural space: It lies between the dura matter and the wall of the vertebral canal. It contains the internal vertebral venous plexus. 7 DR. WAGIH EL-HUSSEINY C.N.S. 1  Lumbar puncture: ✓ The sub-arachenoid space from L2 to S2 called lumbar cistern. ✓ It contains only the filum terminale and roots of lower spinal nerves. ✓ Hollow needles can be introduces safely into this space at L3-L4 or L4-L5 inter-vertebral discs. ✓ This is called lumbar puncture and it is done for the following purposes: 1. Spinal anesthesia as in injection of anesthetic in sub-arachenoid space. 2. To obtain a sample of C.S.F. for diagnosis of meningitis. 3. To inject radio-opaque dye in radiological examination of spinal cord (myelography).  Factors which fix the spinal cord: 1. Attachment of the filum terminale to the back of coccyx. 2. Attachment of the dentate ligament to the dura matter. 3. Attachment of the dura matter to the foramen magnum. 8

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