Skeletal System & Orthopedics

Skeletal System Functions

Support, protection, movement, storage, and blood cell formation.

Hematopoiesis

The process of blood cell formation occurring in bone marrow.

Compact Bone

Dense, homogeneous tissue that forms the strong portions of bone.

Spongy Bone

Composed of small, needle-like pieces found inside certain areas of bones.

Short Bone Examples

Wrist bones and ankle bones.

Flat Bone Examples

Skull and ribs.

Irregular Bone Example

The hyoid bone.

Diaphysis

The main shaft of a long bone, made primarily of compact bone.

Periosteum

Fibrous connective-tissue membrane covering the outside of a bone.

Epiphysis

The ends of a long bone containing spongy bone enclosed by compact bone.

Epiphyseal Plate

A plate of cartilage that indicates a bone is still growing in length.

Medullary Cavity Contents

Contains red bone marrow in children and yellow bone marrow in adults.

Endosteum

A membrane that lines the medullary cavity and inside of bones.

Articular Cartilage

Cartilage located on the ends of bones where they meet at a joint.

Calcification

The deposition of calcium.

Ossification

Bone formation.

Osteocytes

Mature bone cells.

Hyaline Cartilage Model

The model from which bone formation and ossification begin.

Bone Remodeling Triggers

Calcium levels and gravity/mechanical forces.

Osteoblasts

Bone-forming cells that build bone and deposit calcium (Blast = build).

Osteoclasts

Cells that break down bone and release calcium (Clast = crush).

Decreased Blood Calcium

Osteoclasts become active, break down bone, and release calcium into the blood.

Increased Blood Calcium

Osteoblasts become active and deposit calcium into the bones.

Osteoporosis

A condition where bones become fragile and bone density decreases.

Rickets Cause

A lack of vitamin D or an inability to absorb it, leading to improper calcification.

Arthritis

Inflammation of a joint characterized by pain, stiffness, and swelling.

Osteoarthritis (OA)

Chronic, degenerative arthritis caused by wear and tear over time.

Rheumatoid Arthritis (RA)

Chronic, inflammatory autoimmune disease where the immune system attacks body tissues.

Gout

A condition caused by uric acid crystals being deposited in the joint space.

Anterior Cruciate Ligament (ACL)

Prevents the tibia from sliding too far forward relative to the femur.

Posterior Cruciate Ligament (PCL)

Prevents the tibia from sliding too far backward relative to the femur.

Medial Collateral Ligament (MCL)

Resists valgus stress (knees going out).

Lateral Collateral Ligament (LCL)

Resists varus stress (knees going in).

Menisci

Thick bands of cartilage located between the femur and tibia.