Unit 7: Skeletal System

Functions of the Skeletal System

Support and protection, body movement, blood cell formation (hematopoiesis), and storage of inorganic materials.

Hematopoiesis

The formation of blood cells, occurring in the bone marrow.

Axial Skeleton

Composed of the head, neck, and trunk including the skull, hyoid bone, vertebral column, and thoracic cage.

Appendicular Skeleton

Composed of the pectoral girdle (scapula, clavicle, arms) and pelvic girdle (coxal bones, legs).

Epiphysis

The end of a long bone, nearest to the center of the body is proximal; the farthest is distal.

Diaphysis

The shaft of a long bone.

Articular Cartilage

Hyaline cartilage that provides padding at the ends of long bones.

Periosteum

A membrane that covers the entire bone.

Medulla

The central cavity of a bone, containing marrow.

Compact Bone

The dense outer layer of bone.

Spongy Bone

Cancellous bone found at the epiphyses, containing red marrow.

Osteocytes

Mature bone cells enclosed in tiny chambers called lacunae.

Lacunae

Tiny chambers that house osteocytes.

Lamellae

Rings of bone matrix around the Haversian canal.

Haversian Canal

A canal that houses blood vessels in bone.

Canaliculi

Tiny canals that link osteocytes, allowing nutrient exchange.

OSSIFICATION

The process of bone formation from hyaline cartilage.

Primary Ossification Center

The area where bone diameter increases.

Secondary Ossification Center

The area where bone length increases.

Osteoblasts

Cells that create osteocytes during bone formation.

Osteoclasts

Cells responsible for bone resorption.

Epiphyseal Disk

A growth plate of cartilage between the epiphysis and diaphysis.

FOP (Fibrodysplasia ossificans progressiva)

A mutation causing soft tissue to turn to bone.

Synarthrotic Joint

An immovable joint, such as sutures in the skull.

Amphiarthrotic Joint

A slightly movable joint, such as the vertebrae.

Diarthrotic Joint

A freely movable joint, also known as a synovial joint.

Ball and Socket Joint

A joint allowing circular motion, found in the shoulder and hip.

Hinge Joint

A joint allowing movement in one plane, found in the elbow and knee.

Pivot Joint

A joint allowing rotation, as in the lower arm.

Saddle Joint

A joint allowing movement in different planes, such as the thumb.

Coronal Suture

The connection between the frontal and parietal bones.

Lambdoidal Suture

The connection between the occipital and parietal bones.

Squamosal Suture

The connection between the temporal and parietal bones.

Sagittal Suture

The connection between the parietal bones.

Foramen

Any opening in the skull where nerves and blood vessels exit.

Cervical Vertebrae

The first seven vertebrae of the vertebral column (C1-C7).

Thoracic Ribs

12 pairs of ribs formed from true ribs, false ribs, and floating ribs.

Osteoporosis

A condition where bone density decreases, causing fragility.

Rheumatoid Arthritis

An autoimmune disease causing joint stiffness and deformity.

Rickets

A deficiency of Vitamin D leading to weak, brittle bones.

Fibrodysplasia ossificans progressiva (FOP)

A condition where soft tissue regrows as bone.

Osteosarcoma

The most common bone cancer affecting long bones, primarily in teenagers.

Kyphosis

A hunchback curvature of the spine.

Lordosis

A swayback curvature of the lower spine.

Ankylosis

A fusion of bones, leading to reduced mobility.