Intro to Skeletal System

MAIN FUNCTION OF THE SKELETAL SYSTEMStructural Support Framework for soft tissue

Protection Skull BrainRib Cage Lungs & HeartVertebral Column Spinal Cord

Blood Cell Formation Red blood cells and platelets are made in bones

Reservoir of Minerals Regulate level of calcium and phosphorous in the body

Movement Muscle attach to bone by tendons – contract and move bones to facilitate movement

Axial vs Appendicular Skeleton

The axial skeleton consists of 80 bones:• 26 vertebral column, 1 hyoid, 22 skull, 6 auditory & 24 ribs• Most muscles anchor & originate here

The appendicular skeleton consists of 126 bones:• 64 upper extremity – attached to pectoral girdle• 62 lower extremity – attached to pelvic girdle• Key role in movement

Axial (80) + Appendicular (126) = 206 bones

Types of Bones

1. Long2. Short3. Flat4. Irregular5. Sesamoid

Bones classified according to their shape

Anatomy of a Long BoneAnatomy of a Long BoneCartilage

Compact bone

Periosteum

Cancellous bone

Medullary cavity

Epiphysis

Diaphysis

Epiphysis

Definitions to Know

• Articulating Cartilage– Located at both ends of long bone– Function: protection & smooth movement within joints

• Perisoteum– Outer connective tissue covers

entire length of bone– Function: attachment site for

tendons & ligaments

• Diaphysis– Shaft of bone

• Epiphysis– End of bone

• Compact Bone– Dense part of bone (hard)– Structural integrity– Diaphysis

• Cancellous (Spongy) Bone– Filled with marrow– Can strengthen with exercise– Epiphysis

• Medullary Cavity– Inside shaft of bone– Filled with:• Red bone marrow–Blood-cell formation

• Yellow bone marrow–Fat cells & connective tissue