 1. Support: provides the framework that supports the body and organs.  2. Protection: provides safety from outside blows to major organs like the brain, heart, and lungs.  3. Movement: only when coupled with muscles can the skeletal system provide movement.  4. mineral storage: store minerals such as calcium and phosphorus.  5. Blood cell formation: hematopoiesis performed in the red marrow of bones.

 Hyaline: looks like frosted glass and provides support along with flexibility and resilience.  Elastic: contains many elastin fibers.  External ear and eppiglottis.  Fibrocartilage: compressible  -vertebral column, knees

 Axial Skeleton: skull, ribs, vertebral column

 1. long bone: any bone that is longer than it is wide.  2. Short bone: any bone that is as short as it is wide  3. Flat bone: any bone that is flattened.  4. Irregular bone: any bone that is not long, short, or flat.

 1. Spongy bone: internal bone and looks like a honeycomb of needles and filled with red or yellow marrow.  2. Compact bone: external bone that appears solid, homogenous, and solid.

 1. Diaphysis: shaft of the long bone. Constructed of compact bone surrounding the medullary cavity.  2. Medullary cavity: hollow region in the diaphysis. Called the marrow cavity  A. red marrow: performs hematopoiesis, (produces blood cells)  B. yellow marrow: stores and produces fat.  3. Epiphysis: ends of the long bone. More expanded in many cases. Covered in hyaline cartilage- protects bone ends.

 4. Epiphyseal plate: growth plate. Line of hyaline cartilage that causes longitudinal growth of long bone. Once calcified, the bone cannot grow longer.  5. Membranes: connective tissue membranes that cover all bones.  Periosteum: double layered membrane that is secured to the bone by Sharpey’s Fibers.  Contains both osteoblasts and ostoeclasts  Endosteum: lines the inner cavity.  Contains both osteoblasts and osteoclasts

 Osteocytes: bone cells  Osteoblasts: bone cells that secretes bone matrix that calcifies and becomes compact bone.  Osteoclasts: large bone cells that secrete acids to dissolve bone away  **Osteoblasts always, must out pace osteoclasts.**

 1. At the center of a piece of hyaline cartilage, a bone collar begins to form.  2. cartilage inside the bone collar starts to calcify and cavitate.  3. As this happens, the periosteum sprouts buds that invade and cavitate the hyaline cartilage.  Formation of spongy bone  4. the diaphysis starts to elongate and the medullary cavity forms.  5. the final stage before birth includes the ossification of the epiphysis.

 Ossification  As an embryo, it leads to the formation of a skeleton.  As a child it leads to bone growth.  As an adult, it leads to bone remodeling.

 1. on the diaphysis side, cartilage stacks itself and pushes the epiphysis away from the diaphysis causing the bone to grow in length.  2. Surrounding cartilage calcifies and dies leaving an area of calcified cartilage.  At the end of longitudinal growth, the epiphysis and diaphysis fuse together and the plate closes.  ~ 18yr. female  ~ 21 yr male

 1. Osteoblasts beneath the periosteum secrete bone matrix on the external bone surface.  2. Osteoclasts on the endosteal surface removes bone.  -always have more building than breaking down

 -Does not occur uniformily  Distal portion of the femur is repaired every 5-6 months.  -Bone remodeling is controlled by hormones

 Fractures are classified by how the bone is broken.  1.Displaced: bones do not line up  2. Nondisplaced: bone ends are lined up  3. Complete: bone is broken completely through  4. Uncomplete: bone is only partially broken  5. Linear: break is along the shaft of the bone  6. Transverse/Oblique: break is perpendicular to the shaft of the bone.  7. Open: bone end sticks out of the body and can be seen from the outside.  8. Closed: bone ends do not extend beyond the skin

Spiral: bone is twisted: sports injuries. Epiphyseal: break on the growth plate- children

Comminuted: bone broken into 3 or more fragments. Compression: bone is crushed- elderly

 1. Hematoma: blood vessels bleed into the surrounding area. Bone cells are deprived of O2 and die.  2. Fibrocartilaginous callus formation: capillaries grow into the hematoma and fibroblasts and osteoblasts invade the bone to rebuild.  3. Bony callus formation: within a week, new bone appears as the fibrocartilaginous callus becomes bone. Can last up to 2 months.  4. Bone remodeling: as the bony callus forms, it is restructured for work.

 -less movement around the joint = more stable  Joints are classified based on structure and function  Structure: materials binding bones together and the presence of a joint cavity.  Function: how much movement it allows

 Synarthroses: immoveable joints  Amphiarthroses: slightly moveable joint  Diarthrosis: freely moveable joint

 Suture: seams between bones of the skull.  Syndesmoses: bones connected completely by ligaments.  Gomphoses: peg-in- socket joint

 Synchondroses: hyaline cartilage plate found in the epiphyseal plate of long bone.  Symphyses: articulating surfaces of bones are covered in hyaline cartilage and joined by cartilage

 Joints are joined by a synovial cavity  * freely moveable:  1. plane: gliding (carpals)  2. hinge: move on one plane (elbow)  3. pivot: uniaxial (radius/ulna)  4. condyloid: angular movements (metacarpals and phalanges)  5. saddle: freely moveble condyloid joint (thumb)  6. ball and socket joint: multiaxial joint (hip and shoulder)