1. bones 
2. cartilage
3. ligaments
4. other connective tissues that stabilize and connect bones

1. provide and support framework for
2. store minerals and lipids
3. blood cell production
4. protects
5. leverage

• calcium- 98% deposited in skeleton; important for normal concentrations of calcium, phosphorus, magnesium throughout the body
• yellow marrow- lipid storage (energy source)

• 2/3 calcium phosphate (strong but not flexible)
• 1/3 protein/collagen fibers (tough, flexible)
• 2% only - osteocytes and other cells

1. osteogenic (osteoprogenitor) cells
2. osteoblasts
3. osteocytes
4. osteoclasts

• also called osteogenic cells
• not many of these
• osteoprogenitor cells are undifferentiated cells that divide to produce osteoblasts and when needed (ie. fracture repair trauma)

• osteoblasts are immature cells responsible for the production of new bone through a process called osteogenesis
• secretes an un-miniralized substance that later becomes mineralized, forming bone matrix
• they are found in areas of high metabolism (ie. periosteum, endosteum)

• osteocytes are mature bone cells derived from osteoblasts that have secreted bone tissue around themselves; located in spaces (or lacunae) between layers (or lamelle) of the hard matrix of the bone
• small channels connect the lucunae and are called canaliculi; these provide passage for nutrients, waste products , and hormones (diffusion in and out of microcirculation)
• secretes enzymes and maintain healthy bone and mineral content by regulating calcium release and deposition

• osteoclasts are giant, multinuclear cells that secrete acids that dissolves bony tissue, releasing calcium, phosphate, magnesium and other minerals into the circulatory system to maintain homeostasis for these concentrations in body fluids; this process is called osteolysis
• the breakdown of bone tissue is n enzymatic process, meaning it requires enzymes for osteolysis to take place
• this process, osteolysis, is important for bone growth, healing and remodeling

• cells that are derived from osteoblasts along the surface of most bones in the adult skeleton
• these cells help regulate the movement of calcium and phosphate into and out of bone matrix

• most bones contain both types of bone tissue

1. compact bone
2. spongy bone

• dense bone that forms solid outer wall of bone
• also known as cortex or matrix 
• contains functional units called osteons that usually run parallel to the long surface

1. stresses on bone
2. how many directions that stresses come from 

• concentric lamellae
• lacunae
• canaliculi

1. shaft or diaphysis (spongy bone)
2. medullary cavity
3. endosteum
4. yellow bone marrow (ends of long bones)
5. epiphysis (flaring out)
6. red bone marrow
7. articular cartilage (at the ends, allows bones to touch each other)
8. epiphyseal plate
9. epiphyseal line
10. periosteum
11. perforating fibers

1. endosteum- a thin layer of CT that lines the medullary cavity
2. periosteum- a dense layer of CT that lines the surface of the bone (superficial to endosteum)

1. it separates the bond from the surrounding tissues, but it is continuous with the joint connective tissues and tendons/ligaments
2. it allows a route for circulatory, lymphatic, and nervous supply (without periosteum bone dies)
3. is an active part of bone growth and repair (through osteoblast/osteoclast activity)
4. the periosteum, tendons and ligaments are made part of bond structure by thick bundles of collagen fibers called sharpey's fibers in periosteum cellular layer - very strong bond into matrix of bone

• a thinner membrane of connective tissue that is internal to periosteum
• contains osteoblasts and osteoclasts
• lines the central canal of osteons
• covers the trabeculae of spongy bones
• active in bone growth and repair

• aka trabeculae
• an open structure that is surrounded by compact bone
• surrounds bone marrow or medullary cavity (red and yellow marrow found here)
• no osteons instead trabeculae which are formed by branching lamellae (from matriz) to form a network-like structure

lamallae are connected to ______ of compact bond for nurtrient and nervous supply

• long bones
• trabeculae

lateral

medial

increased bone mass, muscle mass, fibrous mass

• determines the overall size of our bodies
• occurs from approx. 6 weeks embryologically to approx. 25yrs old
• as bones grow, hyaline cartilage or embryonic mesenchyme replaced by bone -this is called ossification and it occurs though calcification (ie. the deposit of calcium salts in tissues)

(1) intramembranous (or dermal) ossification 

(2) endochondral ossification

• occurs in the fetal period (2months-2yrs)
• the bone develops when osteoblasts differentiate within fibrous CT
• usually occurs in the deeper layers of skin or dermis and develops flat bone (ie. skull, mandible, clavicle)
• generally the structure formed is a spongy bone composition but with thin layers of compact bone surrounding

• begins with the formation of hyaline cartilage as a structural model during the fetal period (2-25yr)
• it proceeds to replace the cartilage model with bone
• bone development proceeds initially from a primary center of ossification, which is usually located in the diaphysis of the cartilage system
• bone develops around the circumference also 

the process of adding layers of bone tissue and supporting vessels and innervation to existing bone structures superficially

osteoblasts

diaphysis

ends

1. zone of reserve cartilage
2. zone of cell poliferation
3. zone of cell hypertrophy
4. zone of calcification
5. zones of bone depostion

• dietary calcium and phosphates
• dietary vitamin A and C
• dietary vitamin D

• growth hormone (released from the pituitary) and thyroxine (released from the thyroid gland)
• sex hormones (testosterone, estrogen) - released from reproductive organs, adrenal cortex; responsible for differences in bone growth between sexes

• boxier, no visible long axis
• contains a cortex and spongy bone
• examples include carpals (found in the hands) and tarsals (found in the feet)

• flat, thinner, strong and light
• parallel layers of compact bone sandwiching spongy bone
• large area for attachment of muscle, and protects underlying soft tissue
• examples include the skull, sternum, ribs and scapula

varied structure with surfaces that are short and can be notched ridged or flat

examples include vertebrae, ethmoid bones (located in the skull), and lacrimal bones

• small, round and flat
• develops within tendons (patella of knee or knee cap) or sometimes near the joints of the hands and feet

• small, flat; varied shape
• found between flat bones of skull, invading the suture line
• variation among people as to the number, size and shape

206

age, genetic factors, and bone disorders

1. the axial skeleton
2. appendicular skeleton

1. skull - consists of cranial bones (forms the cranium) and facial bones
2. 3 auditory ossicles - the "ear bones"
3. hyoid bone- located above the larynx and below the jaw or mandible. it supports the tongue and assists in swallowing
4. vertebral column - 26 vertebrae disks (the sacrum can also be considered part of the pelvic girdle
5. rib cage
6. sternum (can be considered part of the pectoral girdle)

1. pectoral girdle - consists of the scapulae (shoulder blades) and the clavicle (collarbones) provides attachment for the muscles that move the arm
2. upper extremities
3. pelvic girdle- the gipbones; supports the weight of the body and protects the organs within the pelvic cavity
4. lower extremeties