Osseous Tissue

Function of Bone  Support  Mineral storage  Protection  Leverage  Blood cell production –erythropoietin

What is the composition of bone?  Bone is supportive CT  Composed mostly of calcium phosphate  Matrix of bone is solid  Collagen fibers form the organic part of the solid bone matrix  Collagen becomes mineralized  Bone is a protein-mineral combination

Types of bone cells  Osteoblasts – bone forming cells  Osteocytes – mature bone cells  Osteoclasts – bone destroying cells

Bone Terminology  Compact bone  Spongy bone  Diaphysis  Epiphyses  Periosteum  Endosteum  Marrow cavity  Epiphyseal line / plate

Bone Structure

Spongy bone

Bone Structure

Microscopic bone structure  Basic structural unit of bone is the OSTEON or Haversian system  Osteons have a central canal and side connecting canals called perforating canals  The concentric rings of the osteons are called lamella and arranged in a concentric pattern  Osteocytes are situated in a lacunae  Small canals connect the lacunae and are called canaliculi  Osteon and the concentric lamella resemble a tree ring  Other types of lamella –Circumferential –intersitial

Bone structure

Bone Histology

Bone Development  Intramembraneous ossification  Rapid process  Bone formation directly form embryonic membranes  Skull bones, clavicle, mandible  Endrochondral ossification  Slower process  Bone develops from hyaline cartilage model  Takes years to complete

Endrochondral Ossification

Endrochondrial Ossification

Bone Growth  Bone grows both in length and width (appositional growth)  Bone is remodeled by the osteoclasts  Bone remodeling = bone replacement, no net bone loss  Bone remodeling ≠ bone replacement then there is bone loss

Epiphyseal cartilage(plate) Epiphyseal line

Bone classification  Long bones – long and slender, epiphysis, diaphysis, and marrow cavity  Short bones – box like in appearance  Flat bone – thin, flat bones. Parallel surfaces of compact bone  Irregular bones – complex shapes  Pneumatized bones - hollow bones  Sesamoid bones – small, round bones that develop in tendons

Bone Markings Depressions and Openings  FISSURE – narrow slit between adjacent parts of bones. Nerve and blood vessel passages. Examples: superior and inferior orbital fissures  FORAMEN – rounded opening in bone. Examples: optic foramen, foramen magnum  FOSSA – shallow depression. Example: cranial fossa, olecranon fossa  MEATUS – large diameter passage through a bone. Example: external auditory meatus

Bone Markings Joints Processes  CONDYLE – smooth rounded articular process (knuckle) at end of bone. Example: medial and lateral condyles of femur  FACET – small, flat articular surface. Example: articular facets of the vertebrae  HEAD – bony expansion on a narrow neck. Example: head of the femur or humerus

Bone Markings Attachments for CT  TUBEROSITY – small, rounded, raised projection. Example: tibial tuberosity, deltoid tuberosity  CREST – prominent narrow ridge of bone. Example: iliac crest  TROCHANTER – large, rough projection. Example: greater and lesser trochanters of femur  LINE – low ridge of bone. Example: linea aspera of femur  TUBERCLE – small, rounded projection. Example: greater and lesser tubercles of humerus  EPICONDYLE – raised area above a condyle. Example: medial and lateral epicondyles of humerus  SPINE – pointed process. Example: Spine of scapula or spine of a vertebrae