Week 2 Flashcards
List the 2 primary curves and the 2 secondary curves
2 primary - kyphotic
- thoracic
- sacral
2 secondary - lordotic
- cervical
- lumbar
How do the secondary curves develop?
developed as we grow (tummy time) then continue to develop as we develop to crawling and sitting
What is the advantage of a curved vertebral column as opposed to a straight rod?
- allows for transmission of forces - increased ability to resist compressive load
- area of transitions are weaker
Define what the motion segment is
- functional unit of the spine
- consists of any 2 adjacent vertebrae, intervertebral disc, and soft tissue that secures them
Describe what happens in a bilateral fracture at the pars interarticularis. Where is this most likely to occur in the spine and why?
- fractures occurs because of insufficient cortical bone
- results in forward slipping of vertebra (spondylolisthesis)
- most common at L5/S1
What transmits tension and bending forces from posterior elements to vertebral body?
pedicles
What is the portion of laminae between superior and inferior articular processes? What stress is it subject to?
- pars intearticularis of Laminae
- subject to bending forces
What forms the articular pillar?
articular processes AKA zygapophyseal joint
What is the function of lamina?
transmit forces from the articular, transverse and spinous processes to the pedicles
What determines size of intervertebral discs?
amount of motion and magnitude of the load that is being transmitted
How is available motion determined in intervertebral disc? Where is motion the greatest-least?
- ratio of disc height to vertebral body height
- larger ratio = greater movement
- greatest in cervical, lumbar, then least in thoracic
What activities and body positions place the most amount of pressure on the intervertebral discs? How can you use this information when educating patients on lifting mechanics?
- high disc pressure when holding load in front with forward bending
- slouching produces greater disc pressure than sitting erect
- used to teach proper lifting and sitting techniques to reduce disc pressure
What 2 factors affect available motion of articular process and facets?
shape and orientation
What is the function of anterior longitudinal ligament?
- limit extenision
- reinforce anterolateral portion of anulus fibrosus and anterior aspect of intervertebral joints
What is the function of posterior longitudinal ligament?
- limits forward flexion and reinforces posterior portion of the anulus fibrosus
What is the function of ligamentum flavum?
limits forward flexion, particularly in lumbar
What is the function of interspinous ligaments?
limits forward flexion
what is the function of supraspinous ligaments?
limits forward flexion
What is the function of intertransverse ligaments?
limits contralateral lateral flexion
What is the function of facet joint capsules?
limits motion and adds stability
describe joint coupling
association of one motion around an axis with another motion around another axis
ex: lateral flexion and rotation
Coupling patterns vary based on what?
- spinal posture
- spinal curvature
- orientation of articulating facets
- fluidity/elasticity/thickness of the discs
- extensibility of the muscles, ligaments, and joint capsules
what part of motion segment determines magnitude of movement?
interbody joints - distributes load and creates space for movement and passage of the spinal nerve roots
what part of motion segment determines direction of movement?
facet joints - “train tracts” that are influenced by geometry, height, and spinal orientation
List the osteokinematic motions that occur in the vertebral column
- flexion/extenison
- lateral flexion/sidebending
- rotation
When describing the arthrokinematics motion occurring at a motion segment we are describing the motion that is occurring by which segment moving on which segment?
superior segment on inferior segment
When we move into flexion, what happens to the posterior aspect of the motion segment? What happens to the anterior aspect of the motion segment?
- anterior tilt and anterior glide of superior vertebra
- posterior - distraction of annulus fibrosis
- anterior - anterior compression of annulus fibrosis
What structures limit the amount of spinal flexion available?
- supraspinous and interspinous ligaments
- tension in facet joint capsules
- ligamentum flava
- posterior longitudinal ligament
- posterior anulus fibrosus
- back extensors
When we move into extension, what happens to the posterior aspect of the motion segment? What happens to the anterior aspect of the motion segment?
- posterior tilt and posterior glide of the superior vertebra
- posterior - compression of annulus fibrosis
- anterior - distraction of annulus fibrosis
What structures limit the amount of extension available?
- bony contact of spinous processes
- tension in facet joint capsuls
- anterior longitudinal ligament
- anterior anulus fibrosis
- anterior trunk muscles
When we move into lateral flexion, what happens to the contralateral aspect of the motion segment? What happens to the ipsilateral aspect of the motion segment?
- lateral tilt, rotation, and translation of superior over inferior vertebra
- contralateral - widening of intervertebral foramen
- ipsilateral - narrowing of intervertebral foramen
What structures limit the amount of lateral flexion available?
- annulus fibrosis
- intertransverse ligament
- trunk muscles
- contralateral side limits lateral flexion
Our ability to resists the loads applied to the vertebral column depend on what factors
- type/duration/rate of loading
- person’s age
- posture
- structural elements
- integrity of nervous system
What is considered upper cervical spine? What is considered lower cervical spine?
upper - occiput, C1 (atlas), C2 (axis)
lower - C3 - C7
List the atypical vertebra in the cervical spine. What are their unique characteristics?
- Atlas - no body or spinous process, shaped like a ring, 2 lateral masses
- Axis - dens, large, bifid spinous process
- C7 - largest cervical vertebra, long spinous process
What are the functions of atlas vertebra?
cradle occiput and transmit forces from occiput to lower C-spine
What are the functions of axis vertebra?
transmit combined load of the heat/atlas to C-spine and provide axial rotation of head/atlas
Summarize the characteristics of the typical vertebra in the cervical spine
- small body w/ uncinate processes to give upper surface concave shape
- transverse foramen for vertebral artery on transverse process
- bifid spinous process
Describe atlanto-occipital joint (OA joint)?
- convex occipital condyles on concave superior facets
- synovial plane joint
Describe atlanto-axial joint (AA joint)
- dens and anterior arch of atlas/transverse ligament
- synovial pivot joint
- biconvex w/ meniscoids - inferior facets of atlas w/ superior facets of axis
What is the role of the transverse atlanto ligament?
- holds dens in place
- prevents anterior displacement of C1 over C2
What is the role of the alar ligament? When is it taut?
- limit lateral flexion and prevent distraction of C1 on C2
- taut during neck flexion and w/ axial rotation
What conditions can comprise transverse ligament and what does this result in?
- long standing RA and down syndrome
- results in instability of C1/C2
What is the orientation of the facet joints in the cervical spine? What does this result in?
45 degrees off frontal and transverse plane - allows for motion in all 3 planes (flexion/extension, rotation, lateral flexion)
Describe what happens in the upper and lower cervical spine with protraction
Upper cervical extension
Lower cervical flexion
Describe what happens in the upper and lower cervical spine with retraction
Upper cervical flexion
Lower cervical extension
what are the arthrokinematics at OA joint flexion?
convex on concave (move in opposite direction)
- occipital condyles anterior roll and posterior slide
what are the arthrokinematics at OA joint extension?
convex on concave (move in opposite direction)
- occipital condyles posterior roll and anterior slide
what are the arthrokinematics at OA joint lateral flexion?
convex on concave (move in opposite direction)
- inferior roll and superior slide
What are arthrokinematics at AA joint rotation to the right?
- right facet slides posterior and left facet slides anterior
What ligament limits rotation at the AA joint?
alar ligament
- left alar ligament limits movement to the right
What ligament limits tilting of atlas at the AA joint with flexion?
transverse ligament
Describe the spinal coupling relationship in the lower cervical spine
- couple in same direction
- lateral flexion and rotation in same direction
What are arthokinematics of facet joints of lower cervical spine during flexion and extension?
flexion - inferior facet slides anterior and superior
extension - inferior facet slides posterior and inferior
What are arthokinematics of facet joints of lower cervical spine during rotation?
ipsilateral - inferior facet slides posterior and slightly inferior
contralateral - inferior facet slides anterior and slightly superior
What are arthokinematics of facet joints of lower cervical spine during lateral flexion?
ipsilateral - inferior facet slides inferior and slightly posterior
contralateral - inferior facet slides superior and slightly anterior
What is the function of cervical spine?
stability and protection - large vertebral canal for spinal cord and transverse foramen for vertebral artery
Describe what happens when an individual assumes forward head posture for an extended period of time
- lead to trigger points and extra tension in muscles because those muscles are extended for a prolonged period of time
Detail a few reasons that may cause a muscular imbalance of the muscles in the cervical spine responsible for maintaining posture
1) Excessive or violent hyperextension movement strain SCM, longus colli and anterior scalenes causing chronic spasm/guarding
2) Inhibition, pain, weakness or fatigability of deep flexors (longis colli/capitis) resulting in SCM and anterior scalene becoming more dominant
3) Ergonomics: protracting to improve visual contact with computer screen
Discuss the mechanism of a whiplash injury
- hyperextension typically exceeds hyperflexion
- Anterior longitudinal ligament and alar ligament vulnerable
- Excessive strain also placed on longus colli and longus capitis
- Position of the neck moves more towards a relatively straight or even slightly flexed c-spine
Patients who suffer a whiplash injury and have a strained or painful longus colli demostrate what difficulties? What is this an example of?
- demonstrate difficulty shrugging shoulders - motion completed by upper trap
- loss of stable cervical attachment which results in the muscle being able to less effectively elevate the shoulders
- example of interdependence of muscle function
What is interdependence muscle function?
One muscles action depends on the stabilization force of another
What muscle if shortened is typically responsible for torticollis?
SCM
What are articulations of TMJ joint?
- Articulation of mandibular condyle and mandibular fossa of temporal bone
- biconcave disc separates upper and lower articulations
What is the function of articular disc in TMJ?
Disc functions to cushion the large, repetitive force of mastication
Compare and contrast the capsule in the medial/lateral direction verses the anterior/posterior direction.
- Available joint motion is determined by the elasticity of the joint capsule and ligaments
- capsule is firm medially/laterally
- capsule is thin and loose anterior/posterior
What is the normal resting position of the TMJ and what muscle maintains that position?
- lips closed and teeth several millimeters apart
- temporalis muscle
What osteokinematic motions occur at the TMJ?
- depression/elevation
- protrusion/retrusion
- left and right lateral excursion
What are arthrokinematics of mandibular depression?
- early phase posterior roll
- late phase anterior slide
What are arthokinematics of mandibular elevation?
- early phase posterior slide
- late phase anterior roll
What are arthrokinematics of mandibular protrusion?
anterior and slightly inferior slide of condyle and disc
What are arthrokinematics of mandibular retrusion?
posterior and slightly superior slide of condyle and disc
What are arthrokinematics of mandibular lateral excursion to the left? right?
LEFT
- Left condyle spins and Right condyle slides anterior and to the left
RIGHT
- Right condyle spins and Left condyle slides anterior & to the right
TMJ norms for depression, protrusion, and lateral excursion
- depression - 40-50 mm
- protrusion - lower teeth surpass upper teeth
- lateral excursion - 8-11 mm
What is functional screen for mandibular depression?
2 knuckles = functional
3 knuckles = normal
What symptoms are associated with TMJ disorders?
pain, popping, reduced bite force, reduced ROM with mouth opening, headaches, tinnitus trigger points
What are TMJ deviations?
motion that produces an S curve w/ depression or protrusion
- - can be caused by unilateral tightness
What are TMJ deflections?
Motion that produces a C curve w/ depression or protrusion
- can be caused by unilateral tightness
Compare and contrast articular disc displacement with reduction and without reduction.
W/ REDUCTION - reciprocal click when you open and close jaw
W/O REDUCTION - click only occurs during opening of mouth and they have trouble relocating jaw
How are the TMJ, C-spine and posture related?
- head and neck positions affect tension in cervical muscles which can influence the function of the mandible
