Biomechanics and Kinesiology Flashcards

Arthrokinematics refers to:

Answer: Accessory motions occurring at joint surfaces during osteokinematic movement

Arthrokinematics describes the roll, slide, and spin movements that occur between joint surfaces as a bone moves through its range of motion.

A 'force couple' in biomechanics refers to:

Answer: Two equal and opposite forces acting on opposite sides of an axis to produce pure rotation

A force couple consists of two equal, parallel, opposite forces separated by a distance, producing pure rotation without linear translation, as seen in scapular upward rotation.

The 'lumbrical grip' is characterized by:

Answer: MCP joint flexion combined with IP joint extension, used for holding flat objects

The lumbrical grip involves MCP flexion with IP extension (intrinsic-plus position), ideal for holding flat objects such as a book or tablet.

In open kinetic chain (OKC) exercise, which segment characteristic defines the movement?

Answer: The distal segment is free to move while the proximal segment remains relatively fixed

Open kinetic chain exercises have the distal segment free to move, such as a straight-leg raise or seated knee extension, producing isolated muscle activation.

A 'valgus' force applied to the knee causes:

Answer: Laterally directed force that stresses the medial collateral ligament and medial structures

Valgus force drives the distal segment laterally (knocking the knee inward), creating tensile stress on the medial collateral ligament and compressive stress on the lateral compartment.

Which principle of body mechanics should be emphasized when teaching a patient a safe lifting technique?

Answer: Keep the load close to the body, hips and knees flexed, spine neutral

Keeping the load close minimizes the external moment arm, reducing lumbar compressive and shear forces, while hip and knee flexion recruits the powerful lower extremity muscles.

Scapulohumeral rhythm describes the coordinated ratio of glenohumeral to scapulothoracic movement during arm elevation. The generally accepted ratio is approximately:

Answer: 2:1 (two degrees glenohumeral for every one degree scapulothoracic)

The classic scapulohumeral rhythm is 2:1, meaning for every 3 degrees of shoulder elevation, approximately 2 degrees occur at the glenohumeral joint and 1 degree at the scapulothoracic articulation.