Untitled Quiz

Study Notes

The skeletal system is divided into two parts: the axial skeleton and the appendicular skeleton.
The axial skeleton comprises the bones that form the longitudinal axis of the body, including the skull, vertebral column, and rib cage.
The appendicular skeleton consists of the bones of the limbs and girdles, including the arms, legs, shoulders, and hips.

Support: Bones provide support for soft organs and help maintain body posture.
Protection: Bones protect delicate internal organs, for example, the skull protects the brain and the rib cage protects the heart and lungs.
Movement: Skeletal muscles attach to bones via tendons, allowing movement by acting as levers.
Storage: Bones store fat in their internal cavities, also known as yellow marrow, and minerals like calcium and phosphorus.
Blood Cell Formation: Red blood cell formation takes place in the bone marrow, primarily in the internal cavities of certain bones.

Compact Bone: Dense, smooth, and homogeneous bone tissue.
Spongy Bone: Made up of small, needle-like pieces of bone with numerous open spaces.

Long Bones: Elongated bones with a shaft (diaphysis) and two ends (epiphyses). They are primarily composed of compact bone. Examples include bones found in the limbs, excluding ankle and wrist bones.
Short Bones: Cube-shaped bones primarily composed of spongy bone. Examples include wrist and ankle bones.
Flat Bones: Thin, flattened, curved bones with two layers of compact bone sandwiching a layer of spongy bone. Examples include bones of the skull, ribs, and sternum.
Irregular Bones: Bones that do not fit into any of the above categories, often with complex shapes. Examples include vertebrae and hip bones.

Diaphysis: The shaft of a long bone, primarily composed of compact bone, responsible for the majority of the bone's length.
Epiphyses: The ends of a long bone, consisting of a thin layer of compact bone enclosing spongy bone. Articular cartilage covers the external surface of the epiphyses.
Epiphyseal Plate: A remnant of the growth plate found in young, growing bones, responsible for longitudinal growth.
Medullary Cavity: The hollow space within the diaphysis, typically filled with adipose tissue (yellow marrow). In infants, this cavity contains red marrow, where red blood cell formation occurs.
Periosteum: A fibrous connective tissue membrane covering and protecting the diaphysis.
Sharpey's Fibers: Connective tissue fibers that anchor the periosteum to the underlying bone.

The fundamental unit of compact bone.
Lamellae: Concentric rings of hard intercellular substance.
Lacunae: Small spaces between lamellae housing osteocytes.
Canaliculi: Tiny canals radiating from the lacunae, providing pathways for nutrient delivery and waste removal to osteocytes.
Central (Haversian) Canal: A channel containing blood vessels and nerves that run through the osteon.

Ossification: The process of bone formation, primarily from hyaline cartilage in the embryo.
Two Phases of Ossification:
- Osteoblasts cover the hyaline cartilage with bone matrix.
- The enclosed cartilage model is digested, creating the medullary cavity within the newly formed bone.
Bone Remodeling: A continuous process of bone formation and resorption, crucial for maintaining normal bone proportions and strength during growth and throughout life.

Fracture: A break in the bone.
Closed (Simple) Fracture: A fracture where the bone breaks cleanly without penetrating the skin.
Open (Compound) Fracture: A fracture where the broken bone protrudes through the skin.

A complex process involving several stages, including inflammation, soft callus formation, hard callus formation, and bone remodeling.

Fibrous Joints: Immovable joints where bones are united by fibrous tissue (e.g., sutures of the skull).
Cartilaginous Joints: Joints where bones are connected by cartilage (e.g., intervertebral discs).
Synovial Joints: Freely movable joints characterized by a joint capsule, synovial fluid, and articular cartilage.