Functional Anatomy & Biomechanics Flashcards

According to the convex-concave rule, when a convex joint surface moves on a fixed concave surface, how do roll and glide relate?

Answer: Roll and glide occur in opposite directions

A convex surface moving on a fixed concave surface rolls one way and glides the opposite way.

During glenohumeral abduction, which way does the humeral head glide on the glenoid?

Answer: Inferiorly

The convex humeral head rolls superiorly and glides inferiorly to remain centered during abduction.

In open-chain knee extension, the concave tibial plateau moves on the convex femur; which way does the tibia glide?

Answer: Anteriorly

With concave-on-convex motion, roll and glide occur in the same direction, so the tibia glides anteriorly.

What is the close-packed position of the tibiofemoral joint?

Answer: Full extension with tibial external rotation

The knee is close-packed in full extension with external rotation of the tibia, where congruency and ligament tension are maximal.

Which term describes the movement of bones through space as seen from outside the body, such as flexion or abduction?

Answer: Osteokinematics

Osteokinematics describes gross bone movement through planes, while arthrokinematics describes motion between joint surfaces.

Which arthrokinematic motion best describes the radial head during forearm pronation and supination?

Answer: Spin

The radial head spins on the capitulum, rotating about a fixed axis without translating.

During the final degrees of open-chain knee extension, what does the screw-home mechanism involve?

Answer: Tibial external rotation on the femur

In open chain, the tibia externally rotates on the femur to lock the knee into full extension.

Which type of collagen predominates in tendons, ligaments, and joint capsules?

Answer: Type I

Type I collagen gives dense connective tissues their high tensile strength.

What does mechanotransduction refer to in tissue adaptation?

Answer: Cells converting mechanical load into biochemical responses

Mechanotransduction is how cells sense mechanical stimuli and turn them into signals that drive tissue remodeling.

Which principle states that soft tissues remodel along the lines of mechanical stress imposed on them?

Answer: Davis's law

Davis's law is the soft-tissue counterpart of Wolff's law for bone.

A ligament held under a constant load slowly lengthens over time; what is this viscoelastic property called?

Answer: Creep

Creep is continued deformation under a constant load over time.

A tissue is held at a fixed length and the internal tension gradually decreases; what is this phenomenon?

Answer: Stress relaxation

Stress relaxation is the decline in tension when length is held constant.

The energy lost as heat during a loading and unloading cycle of connective tissue is called what?

Answer: Hysteresis

Hysteresis is the difference between the loading and unloading curves, representing energy dissipated.

Which principle says the body adapts specifically to the type of demand placed on it?

Answer: SAID principle

Specific Adaptation to Imposed Demands means tissues adapt to the exact stimulus applied.

A person cannot fully flex the knee while the hip is extended because the hamstrings are too short to generate force. What is this called?

Answer: Active insufficiency

Active insufficiency occurs when a two-joint muscle is shortened across both joints and can no longer produce effective force.

Limited hip flexion with the knee extended, caused by hamstring tension, is an example of what?

Answer: Passive insufficiency

Passive insufficiency happens when a two-joint antagonist cannot lengthen enough across both joints.

According to the length-tension relationship, at what length can a muscle fiber generate maximal active force?

Answer: Near its resting length

Optimal actin-myosin overlap near resting length allows maximal cross-bridge formation.

How many rotational degrees of freedom does the hip joint have?

Answer: Three

As a ball-and-socket joint, the hip moves in sagittal, frontal, and transverse planes.

The humeroulnar joint is best classified as which joint type?

Answer: Hinge

The humeroulnar joint is a hinge allowing only flexion and extension.

What is the commonly cited overall ratio of glenohumeral to scapulothoracic motion during arm elevation?

Answer: 2:1

Scapulohumeral rhythm is classically described as about 2 degrees of glenohumeral motion for every 1 degree of scapular upward rotation.