Osteology

Osteology

Study of bones

Axial

Skull and vertebral bones

Appendicular

Bones of the appendages, arms and legs

Osteogenesis

Process of bone tissue formation, leads to bone formation of embryos, bone growth in children, bone thickness, remodeling and repair

Osteoid

Nonmineralized, provides flexibility, glycoproteins, protoglycons, and collagen

Hydroxyapatite

main substance that makes bone mature, PROVIDES HARDNESS

Skeletal Cartilages

Hyaline (in the ribs, found on ends of long bones), Elastic (in the ear), Fibrocartilage (in the pubic symphysis, shock absorbing)

Classes of Bones to Know

Long, short, flat, irregular bones

Cells to know: Osteoprogenitor (stem cell) makes Osteoblasts(build bone) and Osteocytes (mature bone cells,maintains matrix)

Osteogenesis (key in bone growth and repair), Osteoblast (build and maintain bone tissue), Osteoclast (break down bone tissue/ bone resorption), Osteocyte (mature bone cells derived from osteoblasts, maintain matrix), Chondrocyte (mature cartilage cell), Chondroblast (form cartilage)

Functions of Bones + Skeleton System

Store minerals (calcium, magnesium, potassium), support, aid in movement(provide levers), protect, form blood cells

Functions of bone markings

Help identify bones, provide attachment points for muscles

Bone texture

Spongy and compact

Structure of long bone

See model on PowerPoint

Intramembranous ossification: Flat bones are formed

Step 1.) Mesenchyme cells are stimulated and cluster together forming osteoblasts, creating an ossification center.

Step 2.) Osteoblasts secrete Osteoids, which calcify in a few days, trapped osteoblasts become osteocytes

Step 3.) Osteoid is laid between embryonic blood vessels, forming spongy bone, and mesenchyme is hormonally stimulated to condense, which forms periosteum

Step 4.) Compact bone replaces immature spongy bone just deep to the periosteum, and red bone marrow develops in the center

Osteoporosis

More bone breakdown occurs than resorption

Osteomalacia/ Rickets

Bones curve outwards, lack of bone deposition

Pagers Disease

Excessive calcium deposition

Kyphosis

Hunched back

Lordosis

Arched back

Scoliosis

Spine curves laterally one way or the other

Zones to Know

Proliferation Zone: Most superior, cartilage cells undergo mitosis, Hypertrophic Zone: Older cartilage cells enlarge, Calcification Zone: Matrix becomes calcified, cartilage cells die, matrix begins to deteriorate, Ossification Zone: New bone is forming, Deepest zone

Bone Processes

Remodeling: Facilitated by remodeling units, Bone Deposition: occurs where bone is injured or added strength is needed, Bone Resorption: Accomplished by osteoclasts that form resorption bays

Fractures to know

Comminuted: Bone fragments into 3 or more pieces, Compression: Bone is crushed, Spiral: ragged break when twisting force is applied, Epiphyseal: Epiphysis separates from diaphysis on epiphyseal plate, Depressed: Broken bone pressed inwards, Greenstick: Bone doesn’t break completely, one side breaks and the other bends

Endochondral Ossification

1.) Bone collar forms around disphysis of the hyaline cartilage material

2.) Cartilage calcifies in the center of the diaphysis and develops cavities

3.) Periosteal bud invades the internal cavities and spongy bone forms

4.) Diaphysis elongates and medullary cavity forms. Secondary ossification centers appear in the epiphyses

5.) Epiphyses ossify, when completely ossified hyaline cartilage only remains in epiphyseal plates and articular cartilage

Appositional Growth: growth in bone width

1.) Osteoblasts beneath the periosteum form ridges that follow periosteal blood vessels

2.) As bony ridges enlarge and meet, the groove with blood vessels becomes a tunnel

3.) Periosteum lining the tunnel is turned into endosperm and osteoblasts secrete bone matrix, narrowing the canal

4.)As osteoblast beneath endosperm form new lamellae a new osteoblasts is created, and the process repeats, enlarging the bone in diameter

Hormonal Regulation

Infants and children epiphyseal plate activity is stimulated by growth hormones

Fracture Repair

1.) Hematoma forms blood/bruise

2.) Fibrocartilaginous callus forms (soft)

3.) Bony callus forms (hard)

4.) Bone remodeling occurs

Fontanels: unossified parts of fibrous membranes between fetal skull bones

Anterior, Posterior, Mastoid, Sphenoid