Kinesiology The Spine Spinal Column Structure 5 Regions of Vertebral Column Curvatures Viewed Laterally
Rubin, Saul, Faculty Advisor has reference to this Academic Journal, PHwiki organized this Journal Kinesiology The Spine Spinal Column Structure Base of support. Link between upper in addition to lower extremities. Protects spinal cord. Stability vs. mobility Example: cervical vs. thoracic spine 5 Regions of Vertebral Column Cervical Thoracic Lumbar Sacral Cocygeal 33 bones in addition to 23 disks
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Curvatures Viewed Laterally Prior to birth C-shaped. 4 distinct curves in an adult. Cervical Lordosis Thoracic Kyphosis Lumbar Lordosis Spinal Motion Spinal movement is the combination of: Intervertebral joints Facet joints
Intervertebral Joints Intervertebral Disc Intervertebral disk make up 20-30% of the height of the column in addition to thickness varies from 3mm in cervical region, 5mm in thoracic region to 9 mm in the lumbar region. Ratio between the vertebral body height in addition to the disk height will dictate the mobility between the vertebra Highest ratio in cervical region allows as long as motion Lowest ratio in thoracic region limits motion Disc Structure Nucleus Pulposus (NP) is located in the center except in lumbar lies slightly posterior. Gelatinous mass rich in water binding PG (proteoglycan) AKA (glycoaminoglycos) GAG-protein molecule. Chondrotin-4 sulfate in PG molecule gives the disc a fluid maintaining capacity (hydrophyllic) – decreases with age. Hydration of the disc will also decrease with compressive loading – this loss of hydration decreases its mechanical function.
Disc Structure 80-90% is H2O decreases with age. Disc volume will reduce 20% daily (reversible) which causes a loss of 15-25 mm of height in the spinal column. Acts as a hydrostatic unit allowing as long as uni as long as m distribution of pressure throughout the disc. Disc Structure Compressive stresses on the disc translate into tensile stresses in the annulus fibrosis This makes the disc stiffer which adds stability in addition to support to the spine. Bears weight in addition to guides motion. Avascular – nutrition diffusion through end-plate. Annulus Fibrosis Collagen arranged in sheets called lamellae (outer layers). These lamellae are arranged in concentric rings -10-12 layers that lessen in number with age in addition to thicken (fibrose). Enclose the nucleus in addition to oriented in opposite directions at an angle of 120 degrees (or 45-65 degrees). Controls the tensile loading from shear, accessory motions in the anterior compartment in addition to disc as long as ces which can be up to 5x the external compression as long as ce.
Annulus Fibrosis Mostly avascular in addition to lacking innervation but the outermost layers are probably innervated (sinovertebral nerve). Thickest anteriorly. Outermost 1/3 connects to vertebral body via Sharpies fibers. Outer 2/3 connect to the end plate. Disc Pathology – Herniation Highest incidence at C5-6, C6-7, L4-5, in addition to L5-S1. Disc herniation Disc protrusion or bulge – contained Annulus intact. Localized usually lateral Diffuse usually posterior Prolapsed not contained Annular fibers disrupted inner layers Extrusion – migration through all layers
Longitudinal Ligaments Anterior longitudinal Supraspinous Posterior longitudinal Ligamentum flavum (elastic) PLL diverts herniation posteriolaterally Posterior Structures (Elements) of Motion Segment Pedicles in addition to lamina as long as m the neural arch. Facet joints between the superior in addition to inferior articulating surfaces. Transverse in addition to spinous processes. Interspinous in addition to supraspinous ligaments. Ligamentum lavum. Intervertebral as long as amina. Facet Joint Articulation between the superior (concave) in addition to inferior (convex) facets. Guide intervertebral motion through their orientation in the transverse in addition to frontal planes.
Facet Joint Capsule Limit motions. Strongest in thoracolumbar in addition to cervicothoracic regions where the curvatures change. Resist flexion in addition to undertake tensile loading in the superior portion with axial loading or extension. Resists rotation in lumbar region. Intervebral Foramina Exit as long as nerve root. The size is dictated by the disc heights in addition to the pedicle shape. Will lose space with osteophytic as long as mation, hypertrophy of ligaments in addition to loss of disc height with aging lateral stenosis. Decreases by 20% with extension in addition to increases 24% with flexion Spinal Stability The columns ability to react to multiple as long as ces placed on it. Degeneration increases instability. Body reacts to restore through fibrosus in addition to osteophytic changes.
Types of Segmental Loading Axial Compression Bending Torsion Shear Axial Compression Caused by gravity, ground reaction as long as ces, muscle contraction in addition to ligaments reaction to tensile as long as ces. Intradiscal loads can range from 294N to 3332N depending upon position. Most load in anterior segment, posterior can load from 0-30% depending upon segments position. Compression at the disk causes tension at the annulus, changing the angle of the fibers in addition to increasing the stability. Axial Compression (contd) Creep will occur in the disc, will be larger with increased as long as ce in addition to aging. 5-11% of H2O is lost through creep. Creep is rapid 1.5-2mm in 10 min. Plateaus at 90 minutes.
Bending Combination of compression, shear in addition to tensile as long as ces on the segment from translation. Bending into flexion will be resisted by posterior annulus, PLL in addition to the facet capsule in addition to anterior compressive as long as ces on the anterior structures causing disc displacement. For extension posterior compressive as long as ces in anterior segment in addition to there is a tensile load in facet capsule in addition to ALL. Torsion Caused by axial rotation in addition to coupled motions. Stiffness may increase due to facet compression with certain motions i.e., flexion increases torsional stiffness at L3-4. Annulus fibrosus resists, 1/2 fibers CW other 1/2 CCW facets may help depending upon the orientation (resists in a tensile manner). When combined with flexion the amount of as long as ce required as long as tissue failure is decreased. Shear Facet joint resists especially in the lumbar area. Annulus will undergo some tensile as long as ces depending upon direction in addition to the fiber orientation or angle. Discs also resist but if creep occurs – the facet may undergo more loading.
Mobility Amount in addition to direct of motion in a segment is determined by: Vertebral body/disc size. Facet orientation frontal vs. sagittal. Flexion Superior vertebra will anterior tilt in addition to as long as ward gliding will occur: Widening the intervertebral as long as amina 24%. Adds compressive as long as ces on the anterior aspect of the anterior segment moving the nucleus pulposus posteriorly. Tensile as long as ces placed on posterior annulus, flavum, capsule in addition to PLL. Central canal is widened Rationale as long as some of Williams flexion exercises Extension Superior vertebra will tilt in addition to glide posteriorly in addition to the intervertebral as long as amina narrowed up to 20%. The central canal is also narrowed. Nucleus pulposus moves anteriorly
General Comment Regarding Function Contracture of hip flexors in addition to effect on lumbar spine General Comment Regarding Function Abdominals Pelvic stability/balance Guy-support system
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