Lecture 1 Flashcards
Describing Motion
Importance of Biomechanics
- helps identify when spine is moving abnormally by knowing how it works normally
- identifying the force/loads spine has been exposed to through patients
Spinal Motion Segments
Typical Spinal Functional Unit
- C2/C3 to L4/L5
Spinal Motion Segments
Atypicial Spinal joints
- C0/C1
-C1/C2
-L5/S1
-Sacroiliac joint
-Sacrococygeal joint ( considered apart of the spine.)
What does each spinal motion segemet have
Each has a unique
-Appearance
-Facet orientation
-Pattern of motion
-Instantaneous Axis of Rotation (IAR)
How do you describe the movement/postion of a mtoion segement by convention?
ALWAYS with respect to the vertebra below. (posterior)
IAR
Instantaneous Axes of Rotation
What does IAR mean?
When an object moves, the axis around which the movement occurs can change in placement from one instant to another. The IAR is used to denote this point.
So with each movement of flexion, neutral and extension movement the IAR is moving of the head
Describe movement
right-handed orthogonal coordinate system - a way to describe movement of the spine
- human body is 3D function therefore 3 axis in right angled. +x +y & +z
y axis poles
superior +
inferior -
x axis
left +
right -
z axis
anterior +
posterior -
saggital plane
Left and right
coronoal
anterior
posterior
transverse
superior
inferior
medially
Whar forms the y-axis?
intersection of sagittal and coronal (frontal) planes
What forms the x- axis
Formed by intersection of frontal and transverse planes
What forms the z- axis
formed by intersection of sagittal and transverse
Describe Degrees of Freedom
The number of coordinates needed to fully describe the motion of an object
- motion of rigid body in space = 6 degrees of freedom
characterised by tranlation along, rotation about and each of the 3 axes - x. y, z
Translation
movement along an axis
3 degrees of Freedom along an axis
+ and - pole on a particular translation movement
Rotation
movement around an axis
3 degrees of freedom around an axis
+ and - rotation about an axis that corresponds to a particular rotational movement
θ
rotation
Cervical Curve
Anterior convex curve (lordosis) develops in infancy – Infant begins to lift head
Thoracic Curve
- Posterior convex curve (kyphosis) present at birth
Lumbar Curve
Anterior convex curve (lordosis) develops in response to weight bearing –
Influenced by pelvis and lower extremity positioning
Sacrococcygeal Curve
Posterior convex curve formed from the fused sacral and coccygeal segments
Postural Analysis
evalutae structure & fuction
doctor from behind (P-A) and laterally
Describe Plumb line
is typically a straight, vertical line that is aligned with the force of gravity
Describe lateral view - postural anaylsis
The plumb line should pass through specific landmarks such as the external auditory meatus (ear canal), shoulder joint, hip joint, knee joint, and ankle joint
Deviations lateral view - postural anaylsis
may indicate postural imbalances or abnormalities
Describe the Postural Analysis- Frontal view
The plumb line can be used to assess any lateral deviations or tilts
- Feet are equidistant from the plumb line
- Feet are parallel
- Through the midline of the body
Importance of assessing Postural Analysis- Frontal view
This is important for identifying asymmetries or uneven weight distribution
Pronation
leaning inward - ankles
Supination
leaning outward
Centre of gravity
The point around which the entire weight of the body is evenly distributed
Where is the centre of gravity in human
2 cm anterior to S2 on an upright body on the average male size/weight
EXAM
What does Centre of gravity depend on
Its dependent upon body build
In women it’s lower due to the wider pelvic girdle and narrower shoulders
