Lecture 2 Flashcards
Forces and loads
What comprises a typical Functional Spinal Unit (FSU) or spinal joint?
A typical FSU is made up of the vertebra above and below, ranging from C2/C3 to L4/L5, where the superior vertebra moves on the inferior vertebra.
Which spinal joints are considered atypical?
Atypical spinal joints include
C0/C1,
C1/C2,
L5/S1,
sacroiliac joint, and symphysis pubis. (not technically - part of spine)
What structures make up a Functional Spinal Unit (FSU)? (9)
two vertebral bodies,
an intervertebral disc between the vertebrae, two facet joints (IAP and SAP),
two facet capsules,
the Posterior Longitudinal Ligament (PLL),
the Anterior Longitudinal Ligament (ALL), t
he Ligamentum Flava,
Interspinous and Supraspinous ligaments
two Intertransverse ligaments.
How are patterns of motion defined in spinal anatomy?
Patterns of motion are defined as the configuration of a path that the geometric center of the body describes as it moves through its range of motion.
What factors determine patterns of motion in the spine?
Patterns of motion in the spine are determined by the orientation of the facet joints and the intervertebral discs.
What is coupled motion in the context of spinal anatomy?
Coupled motion refers to motion in which rotation or translation of a body about or along one axis is consistently associated with simultaneous rotation or translation about or along another axis, representing the normal pattern of motion of all joints of the spine.
What is paradoxical motion in the context of spinal anatomy?
Paradoxical motion occurs when the typical pattern of motion does not occur, potentially indicating instability and deformation of the tissues that make up the spinal column. For example, if a functional spinal unit is supposed to move in flexion or +θX, paradoxical motion would involve movement in extension or -θX.
What is an example of paradoxical motion in the spine?
Paradoxical motion in the spine occurs when there is excessive motion within the Functional Spinal Unit (FSU) or an atypical pattern of motion, such as abnormal coupling or changes in the Instantaneous Axis of Rotation (IAR).
Describe a scenario where paradoxical motion occurs in the spine.
Paradoxical motion can be observed when the overall pattern of motion of one spinal region is in one direction, while the local FSU moves in the opposite direction.
What are some potential causes of paradoxical motion in the spine?
Potential causes of paradoxical motion in the spine include excessive motion within the FSU, abnormal coupling, changes in the Instantaneous Axis of Rotation (IAR), and pathological conditions leading to instability or deformation of spinal tissues.
What are the long-term consequences of paradoxical motion in the spine?
Over time, paradoxical motion can lead to deformation of the associated joints, altering the ability of the structures to manage forces and loads adequately.
What is kinematics?
Kinematics is the study of motion of rigid bodies, without consideration of the forces involved in causing the motion. For example, it examines the range and pattern of motion of spinal joints.
What is kinetics?
Kinetics is the study of the relationship between the forces acting on a body and the changes it produces in the body’s motion. It analyzes external forces (e.g., gravity) and internal forces (e.g., muscle forces) involved in body movement. For instance, it examines how muscles apply forces to bones during activities like running.
What does kinematics focus on in the study of motion?
Kinematics focuses on describing the motion of rigid bodies, including parameters such as displacement, velocity, and acceleration, without considering the forces that cause the motion.
What aspect of motion does kinetics analyze?
Kinetics analyzes the forces acting on a body and their effects on the body’s motion. It considers both external forces (such as gravity) and internal forces (such as muscle forces) involved in movement.
What are potential causes of paradoxical motion in the spine in younger individuals?
Potential causes of paradoxical motion in younger individuals may include ligament laxity, muscle weakness or imbalance, poor posture, congenital abnormalities, or traumatic injuries.
What are potential causes of paradoxical motion in the spine in older individuals?
may include degenerative changes in the spine (such as disc degeneration, facet joint arthritis), spinal stenosis, osteoporosis, muscle weakness or atrophy, and age-related changes in spinal alignment or curvature.
What are external forces in the context of spinal mechanics?
External forces are forces that act on the spine from the outside, including gravitational forces, applied loads (e.g., lifting objects), and external resistance encountered during activities such as pushing or pulling.
Can you provide an example of an external force acting on the spine?
When you lift a heavy object, the weight of the object and the force of gravity are examples of external forces acting on the spine.
What are internal forces in the context of spinal mechanics?
Internal forces are forces generated within the body to counteract or respond to external forces. In the spine, these forces are produced by muscles, tendons, and ligaments to maintain stability, control movement, and resist deformation.
Can you give an example of an internal force acting on the spine?
When you lift a heavy object, your spinal muscles contract to generate internal forces that stabilize the spine, distribute the load, and control movement. These internal forces act as the body’s internal support system.
How are external and internal forces connected in spinal biomechanics?
: External forces and internal forces are interconnected in spinal biomechanics, as the mechanics of deformable bodies involve the relationships between externally applied loads and their internal effects.
What generates forces that load the joints in spinal biomechanics?
Forces that load the joints are generated by muscles and transmitted by tendons in spinal biomechanics.
What is the consequence when a bone is unable to withstand a force in spinal biomechanics?
When a bone is unable to withstand a force in spinal biomechanics, it may result in injuries such as fractures, microfractures, or stress injuries. Additionally, it can lead to degenerative changes in the bone, including bone remodeling or osteoporosis over time.
How is a force defined in the context of biomechanics?
a mechanical disturbance or action that tends to change the state of rest or motion of a rigid body when applied to that body. It is measured in newtons (N).
What two components are necessary to describe any force?
To describe any force, there must be a stated direction (vector) of that force and an indication of how much force is applied, as described by Newton’s second law, F = ma (force equals mass times acceleration).
What does the term “load” refer to in biomechanics?
In biomechanics, “load” is a general term describing the application of a force and/or torque to a structure.
