Skeletal System & Bone Anatomy

• The skeletal system acts as the frame that holds up the body.
• Bone is considered a connective tissue.

Bone Classification

• Bones are classified by their shape.
• Long bones, short bones, flat bones, and irregular bones are types of bone classifications.

Bone Cells

• Osteocytes are mature bone cells and contain calcium and other inorganic mineral salts.
• Osteoblasts are cells that form bone; bones grow in diameter through osteoblast activity.
• Osteoclasts are cells that break down old bone cells.

Basic Bone Anatomy

• The periosteum is composed of tough, fibrous connective tissue.
• The periosteum contains blood vessels that supply nutrients to bone cells and acts as an anchor for ligaments and tendons.
• The epiphysis constitutes the end of a bone.
• The medullary cavity is the inside of the bone that contains bone marrow.
• Bone marrow is where blood cells are created.

Cartilage

• Cartilage, similar to bone, is a form of connective tissue.
• It's firm, has a jelly-like matrix, is somewhat flexible, and can withstand pressure.
• Flexible cartilage is in the nose and ears, while stronger cartilage is between bones in joints.

Joints

• A joint is where one bone meets another.
• Ligaments hold joints together by joining bone to bone, and are known to be very strong structures.

Types of Joints

• Synovial joints move a lot and have synovial fluid.
• Cartilaginous joints allow a little movement, such as where the ribs meet the sternum for breathing.
• Fibrous joints don't move, like where the skull bones fit together.

Types of Synovial Joints

• Gliding joints slide back and forth.
• Hinge joints are in the elbows and knees.
• Saddle joints are in the thumb.
• Pivot joints enable one bone to rotate along another joint.
• Ellipsoidal joints are at the wrists, where the metacarpals meet the radius and ulna.
• Ball and socket joints are at the shoulder and hips.

Movements of the Body

• Flexion involves bending a joint, decreasing the angle.
• Extension straightens a joint, increasing the angle.
• Plantar Flexion is bending down.
• Dorsiflexion is bending up.
• Abduction moves away from the body's midline.
• Adduction moves toward the midline.
• Inversion turns inward, while eversion turns outward.
• Supination faces upward, and pronation faces downward.
• Rotation is when a bone spins on its axis.