17.2 The Skeletal System Life Science, Ms. Wells

Functions of Skeletal System Provides all movement Works with Muscles Skeletal System + Muscular System = Musculoskeletal System

Bone Shapes Long Bone = in arms & legs Short Bone in feet & hands

Bones Shapes Irregular Bones = spinal column (vertebrae) Flat Bones = ribs, skull

Bones are Connective Tissue!

Bone Types Compact Bone Spongy Bone Solid layer Outer layer Very strong Dense calcium network Spongy Bone Lightweight, STRONG Full of holes (for blood vessels) Middle layer

Calcium Network

Spongy Bone

Joints Function: allow for movement or to create a seal between 2 bones Definition: any place where 2 bones meet

Immovable Joints NO movement/motion Example: Skull Bones in skull are fused together to seal brain inside

Slightly Movable Joints Can “give” a little, more flexible But usually don’t move much Example: Ribs

Freely Movable Joints Bones glide back & forth past each other Lots of motion Many types Hinge Pivot Ball and Socket

Freely Movable: PIVOT Joint Motion: twist a door knob Example: wrist

Freely Movable: HINGE Joint Motion: open and close only one way Example: knee, elbow

Freely Movable: BALL AND SOCKET Motion: throwing a baseball Example: shoulder, thigh bone to hips

Ligaments Connective tissue that holds bones together @ joints Stretchy

Osteoporosis Osteo- = bone -porosis = break down, porous, holes Loss of density in bone Calcium network thins Bones become brittle Effects women more than men

“Soft Spot” or Fontanelle Immovable skull joints are not entirely fused in infants Easier to squeeze big head out of mother

Cartilage Bones missing the CALCIUM network! Flexible, soft Example: ears, nose, lining of joints All bones start out as cartilage Add calcium to harden = OSSIFY

Cartilage & Joints Cushions joints so bones don’t grind Arthritis = cartilage covering bones in joints wears down which causes pain and limits movement

THE END!