OT211 - SKELETAL SYSTEM

SKELETAL SYSTEM

• Rigid framework of the human body

• Gives support and shape to the body 

• Protects vital organs such as the brain, spinal cord, and heart

• Assists in movement by providing a rigid structure for muscle attachment and leverage

• Manufactures blood cells in various locations

TYPES OF SKELETON

Axial Skeleton and Appendicular Skeleton

AXIAL SKELETON

• Forms the upright part of the body

• Consists of approximately 80 bones of the head, thorax, and trunk

APPENDICULAR SKELETON

• Attaches to the axial skeleton 

• Contains the 126 bones of the extremities

BONES

• Can be considered as organs

• Made up of several different types of tissue (fibrous, cartilaginous, osseous, nervous, and vascular)

• They function as integral parts of the skeletal system

COMPOSITION OF BONES

• One-third organic (living) material

  • gives the bone elasticity

• Two-thirds inorganic (nonliving) material

  • provides hardness and strength

COMPACT BONE

• Makes up a hard, dense outer shell 

• Completely covers bone

• Tends to be thick along the shaft and thin at the ends of long bones 

• Thick in the plates of the flat bones of the skull

CANCELLOUS BONE

• Porous and spongy inside portion called the trabeculae 

  • “little beams” in  Latin

  • tend to be filled with marrow and make the bone lighter

• Arranged in a pattern that resists local stresses and strains 

• Makes up most of the articular ends of bones

BONE STRUCTURES

• Epiphysis

• Diaphysis

• Metaphysis

• Periosteum

EPIPHYSIS

• Area at each end of a long bone

• Tends to be wider than the shaft

• In adult bone = osseous

• In growing bone = cartilaginous material called the epiphyseal plate

EPIPHYSEAL PLATE

• Longitudinal growth occurs here through the manufacturing of new bone

• On an x-ray, a growing bone will show a distinct line between the epiphyseal plate and the rest of the bone

• Because this line does not exist in the normal adult bone, its absence indicates that bone growth has stopped

TWO TYPES OF EPIPHYSIS

• Pressure Ephysis

• Traction Epiphysis

PRESSURE EPIPHYSIS

• Located at the ends of long bones, where they receive pressure from the opposing bone making up that joint

• Where growth of long bones occurs

TRACTION EPIPHYSIS

Located where tendons attach to bones

DIAPHYSIS

• Main shaft of bone 

• Made up mostly of compact bone

  • Gives it great strength

MEDULLARY CANAL

Center of the Diaphysis

ENDOSTEUM

Membrane that lines the medullary canal

METAPHYSIS

• The flared part at each end of the diaphysis in long bones

• Made up mostly of cancellous bone

• Functions to support the epiphysis

PERIOSTEUM

• Thin fibrous membrane covering all of the bone except the articular surfaces (covered with hyaline cartilage)

• Contains nerve and blood vessels that are important in providing nourishment, promoting growth in diameter of immature bone, and repairing the bone

• Serves as an attachment point for tendons and ligaments

TYPES OF BONES

• Long Bones

• Short Bones

• Flat Bones

• Irregular Bones

• Sesamoid Bones

LONG BONES

• Their length is greater than their width 

• The largest bones in the body and make up most of the appendicular skeleton 

• Are tube-shaped with a shaft (diaphysis) and two bulbous ends (epiphysis)

SHORT BONES

• Have more equal dimensions of height, length, and width, giving them a cube shape

• Have a great deal of articular surface and, unlike long bones, usually articulate with more than one bone

FLAT BONES

• Have a very broad surface but are not very thick

• Tend to have a curved surface rather than a flat one 

• Made up of two layers of compact bone with cancellous bone and marrow in between

IRREGULAR BONES

• Have a variety of mixed shapes, as their name implies

• Composed of cancellous bone and marrow encased in a thin layer of compact bone

SESAMOID BONES

• Resemble the shape of sesame seeds

• Are small bones located where tendons cross the ends of long bones in the extremities

FRACTURE

• A.k.a. broken bone, or cracked bone 

• A break in the continuity of the bony cortex caused by direct force, indirect force, or pathology

OSTEOPOROSIS

• Characterized by loss of normal bone density, or bone mass 

• Can weaken a bone to the point it will fracture

OSTEOMYELITIS

• An infection of the bone usually caused by bacteria

• A fracture that breaks through the skin (open fracture) poses a greater risk of developing osteomyelitis than a fracture that does not break the skin (closed fracture)

OSGOOD-SCHLATTER DISEASE

A common condition at the traction epiphysis of the tibial tuberosity in children