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General Function of Vertebral Column
- Support for head and internal organs
- Stable attachment for all soft tissues, extremities, rib cage, and pelvis
- Protection of internal organs and spinal cord
- Attenuates forces from above and below
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Components of Vertebral Column
- 24 freely moveable and 9 fused bones
- 5 distinct regions (cervical, thoracic, lumbar, sacral, and coccygeal)
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Cervical Regional Variations
- 2 atypical (atlas and axis) allow for increased AROM in rotation without compressing SC
- Uncinate Joints/Processes (Joints of Von Lushka): found at C3-C7, limit lateral cervical movement
- Transverse forament
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Thoracic Regional Variations
- Costotransverse articulations: between rib and TP
- Costovertebral articulations: between rib and vertebral body
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Rule of Threes
- SP of T1-T3 even with TP of same level vertebra
- T4-T6 SP found 1/2 level below TP of same level
- T7-T9 SP 1 full level below TP of same level
- T10 full level below
- T11 1/2 level below
- T12 is level
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Atlanto-Occipital Joint
- Synovial articulation between occiput and C1
- "Yes joint" = much of head nodding motion comes from this articulation
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Atlanto-Axial Joint
- Nonsynovial articulation between dens of C2 and ant arch of C1
- "No joint" = much of head rotation comes from this articulation
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Apophyseal/Facet Joints
- Guide movement of the spine
- Synovial/diarthrodial
- Capsule and synovial membrane
- Composed of superior and inferior articulatory processes of adjacent vertebrae
- Surfaces flat or curved in lumbar region, flat in cervical and thoracic regions
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Intervertebral Joints
- Between intervertebral disc and adjacent superior and inferior vertebral bodies
- Allow movement between vertebral bodies
- Transmit loads from one vertebral segment to another
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Sacroiliac Joint
- Composed of auricular-shaped joint surfaces of sacrum and ilium
- Diarthrosis/synarthrosis (syndesmosis) combination
- Ilial articulation convex and covered with thin layer of fibrocartilage
- Sacral articulation concave and covered with hyaline cartilage
- Attenuates forces from trunk and LE's
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Fibroadipose Meniscoid
- Structure composed of dense connective tissue and adipose tissue
- Found at superior and inferior aspects of facet joints
- Protects cartilage of facet surface during extremes in motion
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Annulus Fibrosis
- Concentric layers (lamellae)
- Composed of collagen (type II) and fibrocartilage
- 65% water
- Outer 1/3 innervated by branches of sinuvertebral nerve
- Function: sustain compressive, torsional, shearing, and distraction loads
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Nucleus Pulposis
- Gel with imbibing capabilities
- Composed of water and proteoglycans with minimal amount of collagen (type I)
- 70-90% water
- Avascular and aneural
- Makes up 20-33% heath of vertebral column
- Functions: sustain compressive, torsional, shearing, and distraction loads
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Vertebral Endplate
- Continuous with annulus and nucleus
- Sits inside ring apophysis of vertebral body
- Composed of proteoglycans, collagen, and water
- Also fibrocartilage (on side closest to disc) and hyaline cartilage (side closest to vertebral body)
- Function: provide passive diffusion of nutrients
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Facet Joint Capsule
- Assist ligaments in providing limitation of motion and stability of spine
- Strongest in throacolumbar and cervicothoracic regions
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Thoracolumbar Fascia
- Provides stability of vertebral column when forces is applied
- Acts as corset when tension is creed by contraction of abdominals, gluteals, and lumbar muscles
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Dorsal and Ventral Roots
- Dorsal roots: transmit sensory fibers to spinal cord
- Ventral roots: transmit motor fibers from spinal cord to spinal nerves
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Spinal Nerves
- Connected centrally to SC by a dorsal and ventral root - join to become spinal nerve in the intervertebral foramen
- Divide into dorsal and ventral rami
- Cervical: spinal nerves come out at the level above its associated vertebra
- Thoracic/Lumbar: spinal nerves come out at the level below its associated vertebra
- SC terminates approximately L1-L2 level
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Dorsal Rami
Innervate structures on posterior trunk
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Ventral Rami
- Cervical ventral rami from cervical and brachial plexuses
- Thoracic ventral rami innervate anterior structures of trunk within thoracic region
- Lumbar ventral rami form lumbar and lumbosacral plexuses
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Spinal Arthrokinematics
- Flexion: upper facets glide anteroproximally and tilt forward
- Extension: upper facets move downward, slightly posterior, and tilt backward
- Sidebending: SB to the R = upper facet moves down and slightly ant, L facet moves upward and slightly post, both facets move to the L
- Rotation:
- --> Cervical causes facets on R to glide down and back, causing approximation of facet joints on the R
- --> Lumbar/thoracic = very little but motion causes separation and approximation of facet joints (i.e. L3 rotates R = separation at R L3-L4 and approximation at L L3-L4 joint)
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Cervical Spine: Coupled Motions
- Sidebending and rotation occur in the same direction from C2-C7
- When occiput side bends, C1 rotates in opposite direction
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Lumbar/Thoracic Spine Coupled Motions
- Neutral/extension: lumbar segments will side bend and rotate in opposite directions (SB R results in segment rotating L)
- Flex: lumbar segments will side bend and rotate in the same direction
- Significant variations exist
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Lumbopelvic Rhythm
- During flexion, spine (primarily lumbar) goes through 60-70 degrees of motion --> then pelvis will rotate anteriorly --> eventually followed by flexion of hips
- During extension (coming from flexed position), hips extend, pelvis rotates posteriorly, then spine begins to extend
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SIJ Osteokinematics
- Motion limited but during gait, movements take place in multiple plains
- Nutation and counternutation: coupling movement that occurs between sacrum and ilium during gait
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Nutation
Involves flexion of sacrum and posterior rotation of ilium
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Counternutation
Involves extension of sacrum and anterior rotation of ilium
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TMJ Functional Anatomy
A bilateral articulation between mandible and cranium (craniomandibular joint)
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TMJ Arthrology
- Synovial joint
- Articular surfaces covered by dense fibrous connective tissue
- Articular disc without blood vessels or nerves in pressure bearing areas
- Discal ligaments function to restrict movement in sagittal plane
- Superior retrodiscal lamina (superior stratum): composed of elastic tissue, counteracts forward pull of sup lat pteryoid muscle on articular disc
- Retrodiscal pad: consists of loose neurovascular connective tissue
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TMJ Movement
- Combination of hinge axis rotation in disc condyle complex and sliding movement of upper joint
- Functional range of opening = 40 mm with 25 mm of rotation and 15 mm of translators glide
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