Skeletal System: General Osteology Comparative Anatomy Dr. Tony Serino Biology Department Misericordia Univ.

Skeletal System Composed of mineralized CT and their supporting structures including: bone, cartilage, ligaments, tendons, and bursae Functions: support, protection, homeostasis (specifically Ca++ regulation) and hempoiesis

General Osteology Composition Cells –originate from mesechyme (undifferentiated mesodermal cells) Extracellular Matrix Ground substances: water, salts, cementing substances, glycoproteins Fibers: collagen and elastin

Cartilage Avascular CT Appositional and interstitial growth possible Perichondrium Chondroblast Lacuna Chondrocyte Matrix

Hyaline Cartilage

Elastic Cartilage

Fibrocartilage

Cartilage in Adult

Bone Heavily mineralized CT Highly vascular Principle storage area of Calcium Provides strength and structural support to body

Long Bone Anatomy

Flat Bone Anatomy Trabeculae

Bone Histology

Haversian System Lamellae

Ossification Development of bony tissues First bone to form is woven (premature) bone This is eventually replace by mature bone (compact or spongy bone) Two methods for creating bones: Intramembraneous (bone replaces mesoderm membrane) Endochondral (bone replaces an intervening cartilage model)

Intramembranous Ossification (Membrane bone formation)

Endochondral Ossification (Replacement Bone formation)

Epiphyseal (Growth) Plate Reserve Cartilage (distal perichondrium) Proliferating Cartilage (Growth zone) Hypertrophic zone (Transforming zone) Calcified matrix (Osteogenic zone)

Fracture Healing

Other Skeletal Tissue Dentin –formed from odontoblasts; lay down dentin layer and retreat leaving small canaliculi (dentinal tubules); fond only in vertebrate teeth, and ganoid and placoid scales Acellular bone (aspidin) –found in modern fish scales and cementum of teeth; from osteoblasts that create matrix and retreat without canaliculi Enamel –secreted by ameloblasts; derived from ectoderm; secretes enameloid on dentin layer by enamel organ which dies when scale or tooth erupts through epidermis

Divisions of Skeletal System Axial Skeleton Fig. 7.1

Appendicular Skeleton Fig. 7.21

Types of Bones

Sesamoid Bones

Wormian (Sutural) Bones (Wormian Bone)

Articulations Functional Classifications Structural Classification Synarthrotic (immovable) Amphiarthrotic (slightly movable) Diarthrotic (movable) Structural Classification Fibrous –held by fibrous tissue Cartilaginous –held by cartilage Synovial –synovial cavity within joint

Suture (synarthrotic, fibrous joint) Found in bones of skull

Gomphosis (synarthrotic, fibrous) Ligament cemented to tooth surface

Syndesmoses (amphiarthrotic, fibrous)

Synchondroses (Synarthrotic, cartilaginous) Epiphyseal Plate

Synchondroses (synarthrotic, cartilaginous)

Symphyses (amphiarthrotic, cartilaginous) Includes pubic symphysis

Synovial = diarthrotic joints The synovial membrane filters the blood to create synovial fluid This fluid lubricates and nourishes the joint Some joints may have an additional wedge of cartilage within the joint (menisci) Fig. 8.3

Knee (Anterior view)

Rotator Cuff of Shoulder

Bursae