skeletal

Cartilage

A flexible, load-bearing connective tissue that serves as the fetal precursor to many bones and persists in adults at joints and in deformable structures like the respiratory tract.

Hyaline Cartilage

Firm, smooth, and opalescent cartilage found in joints, nose, and trachea.

Fibrocartilage

Dense, fibrous, and tough cartilage found in intervertebral discs and menisci.

Elastic Cartilage

Cartilage containing elastic fibers, found in the external ear and epiglottis.

Microstructure of Cartilage

Composed of collagen fibers (mostly Type II) and elastic fibers embedded in a highly hydrated proteoglycan gel, covered by a fibrous perichondrium except at joints.

Extracellular Matrix

Made up of collagen and elastic fibers in a proteoglycan gel, attracting water for compressive strength and load distribution.

Interstitial Growth

Growth mechanism where chondroblasts divide within the matrix.

Appositional Growth

Growth mechanism where new cells form from the perichondrium, adding layers to the surface.

Hyaline Cartilage Characteristics

Glassy and smooth, contains chondrocytes in a matrix of Type II collagen and proteoglycans, found in joints and respiratory structures, with poor regenerative capacity.

Fibrocartilage Characteristics

Combines tensile strength with the ability to resist compression, found in intervertebral discs and knee menisci, contains a mix of collagen Type I and Type II.

Elastic Cartilage Characteristics

Contains elastic fibers, found in areas needing flexibility like the external ear, resistant to degeneration, capable of limited regeneration.

Matrix Turnover

Slow collagen turnover makes cartilage vulnerable to aging, while proteoglycans turnover faster, with an estimated time of 5 years in adults.

Bone

A strong, rigid connective tissue evolved for fast terrestrial locomotion, providing structural support, protection, and mineral storage.

Compact Bone

Dense, ivory-like texture forming the outer shell of bones, providing strength and rigid articular surfaces.

Trabecular Bone

Honeycombed with large cavities, consisting of a latticework of trabeculae, reducing bone weight while providing structural support.

Red Marrow

Involved in blood cell production (hematopoiesis), predominant in children, found in certain adult bones like the pelvis and sternum.

Yellow Marrow

Primarily composed of adipose tissue (fat storage), increases with age, found in long bones.

Bone Surface Markings

Features like processes, spines, tubercles, crests, fossae, grooves, foramina, canals, facets, and condyles that indicate various anatomical structures.

Bone Extracellular Matrix

Composed of water, organic components (mostly Type I collagen), and inorganic components (mainly hydroxyapatite crystals).

Collagen in Bone

Type I collagen provides structural framework and tensile strength, arranged into woven and then lamellar bone for strength.

Bone Mineralization

Process of hydroxyapatite crystal deposition within the collagen matrix, essential for bone hardness and rigidity.

Osteoblasts

Bone-forming cells that synthesize and secrete bone matrix and initiate mineralization.

Osteocytes

Mature osteoblasts embedded in bone matrix, maintaining bone tissue and regulating mineral content.

Osteoclasts

Large, multinucleated cells that resorb bone by secreting acids and enzymes.

Periosteum

Dense, fibrous membrane covering the outer surface of bones, involved in growth, repair, and attachment for tendons and ligaments.

Endosteum

Thin, vascular membrane lining the inner surfaces of bones, containing osteoprogenitor cells and osteoblasts.

Intramembranous Ossification

Direct formation of bone from mesenchymal tissue, occurring in flat bones like the skull.

Endochondral Ossification

Bone development by replacing hyaline cartilage, responsible for long bone formation and growth in length.

Bone Remodeling

Continuous process of bone resorption and formation, maintaining strength and adapting to mechanical stress.

Factors Influencing Bone Health

Hormones, nutrition, physical activity, age, and genetics all play roles in bone health and remodeling.