Movement Understanding and Biomechanics

Describing movement; covered some osteophytic terms.
Movement originates in the brain.
Initial weeks focus on definitions with limited immediate application.
Content is lower level and definition-heavy.
Central Nervous System (CNS) vs. Peripheral Nervous System (PNS): Initial focus may feel overwhelming due to unfamiliarity with CNS, but the knowledge will be applied as we move to the PNS.
Example: Being pushed and reacting involves signals from the point of contact to the brain, then from the brain to the muscles to move away.
Application will increase as we study the somatic system.

Explores the reasons behind movements.
Example of flexion at the elbow:
- Kinematics: Flexion is the observed movement.
- Kinetics: Muscles (biceps brachii, brachialis, brachioradialis) innervated by the musculocutaneous and radial nerves produce the motion.

Translation, rotation, active or passive motion.
Osteokinematics: Described using planes (sagittal, frontal, transverse), axis of rotation, and degrees of freedom.
Kinetics: Defined by forces, muscle contractions, and different levels of exertion.

Ways to define the "what" of motion (kinematics):
- Linear
- Angular
- Curvilinear

A combination of linear and angular motion.
Example: Circumduction (combines flexion, extension, internal/external rotation, abduction, and adduction).
Running the curve on a track.
Functional movements are often curvilinear and involve multiple planes and degrees of freedom.
Requires more than one degree of freedom.

Active Motion: Initiated and performed by the patient (e.g., raising an arm).
Passive Motion: Movement is imposed by an external force; i.e. therapist (e.g., a therapist moving a patient's arm).
Active Assisted Range of Motion: Combination of both; patient actively moves to a point, then therapist assists.

Describing motion based on planes and axes of rotation.
Degrees of Freedom: The number of independent planes (not motions) of movement available at a joint.
- Example: Flexion and extension occur in the sagittal plane, representing one degree of freedom.
- Shoulder joint: Abduction/adduction (frontal plane), internal/external rotation (transverse plane) for a total of three degrees of freedom

Multiple points on one surface make contact with multiple points on another surface.
Example: A tire rolling on the road: different points on the tire contact different points on the road.
Occurs with convex and concave surfaces.

A single point on one surface makes contact with multiple points on another surface.

Example: Humero-radial and proximal radio-ulnar joints.
Turning the hand in and out (pronation/supination).
The radio-humeral joint goes through a spin - a single point on the radius rotates on a single point on the humerus.
Visualizing joint surfaces: Identifying concave and convex structures.

Convex Surface Moving on Concave Surface: The roll and slide (glide) occur in opposite directions.
- If the roll is upward, the slide is downward.
Concave Surface Moving on Convex Surface: The roll and slide (glide) occur in the same direction.
- If the concave surface moves upward, it rolls and slides upward on the convex surface.

Raising the arm (humerus moving on glenoid fossa).
Without the concave-convex rule, the humerus would roll out of the socket (dislocation).
As the humerus (convex) moves upward, the slide must occur in the opposite direction (downward) to maintain joint integrity.
Avoid memorizing patterns; instead, visualize the joint surfaces and motions.
The joint surface will change based on which actual joint we're looking at within the same bone.