Bone Tissue and Skeleton

Cartilage

                Characteristics

                                1) High H₂O content

                                2) Avascular

                                3) Perichondrium – DICT

                                4) Chondrocytes

                                5) Extracellular matrix – ground substance & fibers

                Types

                        1) Hyaline – articular, costal, respiratory, & nasal

2) Elastic – external ear and epiglottis

3) Fibrocartilage – menisci, intervertebral discs, pubic symphysis, annulus fibrosis

Classification – by shape

Function of bone

                1) Support

                2) Protection

                3) Movement

                4) Storage

                5) Blood cell formation

Bone Structure

                Markings

                                1) Attachment

                                2) Articulation

                                3) Passage

                Compact vs. Spongy --> marrow

                Long Bone

                                1) Diaphysis

                                2) Epiphyses

                                3) Membranes

          a) Periosteum – cells, nutrient foramen, perforating fibers, attachment   

          b) Endosteum

Red Marrow

                1) Spongy bone

                2) Hematopoiesis

                3) Samples

                4) Yellow marrow conversion

Microanatomy – Compact Bone

                1) Osteon – structural unit

                2) Central canal

                3) Perforating canals

                4) Cells

                5) Interstitial and circumferential lamella

Microanatomy – Spongy

                1) Trabeculae

                2) Lamella irregularly arranged

Chemical Composition  

                Organic components

                                1) Cells

                                2) Osteoid – ground substance – osteoblasts

                Inorganic components

                                1) Hydroxyapatite (mineral salts)

Bone Development – Ossification/osteogenesis

                Intramembranous

                                1) Ossification center w/in CT membrane

                                2) Matrix secreted

                                3) Network of trabeculae

                                4) Bone collar formation

                Endochondral

                                Hyaline cartilage model

                                Primary ossification center – vascularizing – mesenchymal cells --> osteoblasts

                                Steps

                                                1) Bone collar forms

                                                2) Cartilage begins ossification – diaphysis

                                                3) Periostal bud -- 3rd month

                                                4) Elongation of diaphysis/medullary cavity         

                                                5) Epiphyses ossify – secondary ossification centers, articular cartilage, epiphyseal plates

Growth – Length

                Zones

                                1) Resting (quiescent zone)

                                2) Growth zone

                                3) Hypertrophic zone

                                4) Calcification zone

                                5) Ossification (osteogenic) zone

                                6) Epiphyseal plate

Growth – Width

                Appositional growth – osteoblasts of periosteum and endosteum

                Hormonal regulation – GH, testosterone, estrogen

Bone Remodeling

                Bone deposit and bone resorption (Vit. A, C, D, proteins, minerals)

                Hormonal mechanism

                                1) PTH

                                2) Calcitonin

                Mechanical stress

                                1) Stress

                                2) Diaphysis thickness

                                3) Curved – buckling

                                4) Trabecular

                                5) Projections

Synovial joints

                1) Articular cartilage

                2) Joint cavity

                3) Articular capsule (fibrous capsule and synovial membrane)

                4) Synovial fluid

Types

                1) Hinge

                2) Pivot

                3) Condyloid

                4) Saddle

                5) Ball and socket

Selected Joints

                Shoulder (glenohumeral) – ball and socket

                                1) Glenoid labrum

                                2) Coracoacromial ligament

                                3) Rotator cuff (subscapularis, supraspinatus, infraspinatus, and teres minor)

                Knee – hinge joint

                                1) Ligaments

  2) MCL, LCL, ACL, PCL

  3) Menisci

Imbalances

                1) Sprain

                2) Luxation and subluxation

                3) Cartilage

                4) Bursitis & tendonitis

                5) Arthritis