Unit 1.2 Bones

What are the 4 main purposes of the skeletal system?

1. Protect internal organs, 2. Facilitate muscle action and body movement, 3. Provide muscle attachment sites, 4. Production of Red Blood Cells (RBC).

Bone is the second hardest part of the body, behind what?

Dentin/Enamel.

What is Wolff’s Law?

Bone is adaptive to mechanical demands (it builds with stress/loading and thins with inactivity).

Which minerals give bone its hard and rigid structure?

Calcium and phosphates.

What provides pliability in the bone?

Collagen fibers.

What are the three components of the Axial Skeleton?

Skull (29 bones), Spinal Column (33 bones), and Thorax (25 bones).

What is the primary function of the Appendicular Skeleton?

Primarily for movement.

How many carpals, metacarpals, and phalanges are in the upper extremity (total)?

Carpals

How many tarsals, metatarsals, and phalanges are in the lower extremity (total)?

Tarsals

What defines an Irregular bone?

Asymmetrical shape; designed to withstand direct loading with limited range of motion (Ex

What is the purpose of Flat bones?

Protection (Ex

What are the 2 major purposes of Sesamoid bones?

Protection and increased mechanical advantage (functions as a lever).

What is a common example of a Sesamoid bone?

The Patella.

Where are Short bones generally located?

In unique spaces near gliding joints to provide stability and support (Ex

What is the primary function of Long bones?

To act as long levers for mechanical movement (Ex

What is the Diaphysis of a long bone?

The central shaft.

What is the Epiphysis of a long bone?

The end of the bone that articulates with adjacent bones.

Which part of the long bone is responsible for red blood cell production?

Spongy/Trabecular bone (containing red bone marrow).

What is Longitudinal growth?

Growth in length occurring at the epiphyseal (growth) plate.

What is Circumferential growth?

Cross-sectional growth (widening) that continues forever.

Tension loading

The bone is loaded along its long axis, pulling the bone in opposite directions.

Compression loading

The bone is loaded along the long axis, pushing the bone toward the center.

Bending loading

Forces cause tension on the longer side and compression on the shorter side.

Shear loading

Forces acting in opposite directions across the long axis of the bone.

Torsion loading

Forces cause a twisting force along the long axis of the bone.

Condyle

A rounded process of a bone that articulates with another bone.

Foramen

A hole in a bone through which nerves or vessels pass.

Fossa

A shallow dish-shaped section of bone for articulation or muscle attachment.

Process

A bony prominence.

Tuberosity

A raised section of bone where a ligament, tendon, or muscle attaches.

If a person is inactive for a long period, what happens to their bone density according to Wolff's Law?

It leads to a loss of bone density.

Why are the bones of the hands and feet (Short bones) shaped the way they are?

To provide stability and support while allowing for some fine movements.

In a "bending" load, which side of the bone is most likely to break in an adult?

The side under tension (the longer side).

How does a sesamoid bone like the patella assist the knee joint?

It acts as a fulcrum to provide a mechanical advantage for movement.

Which type of growth has stopped once the epiphyseal plates seal at age 25?

Longitudinal growth (getting taller).