Bones and Skeletal Tissue Flashcards

A set of vocabulary flashcards covering skeletal system functions, bone anatomy, microscopic structures, growth, remodeling, and fracture repair based on the lecture notes.

Axial skeleton

The division of the skeleton that includes the skull, vertebral column, ossicles of the inner ear, hyoid bone, and rib cage.

Appendicular skeleton

The division of the skeleton that includes the shoulder girdle, pelvic girdle, arms, hands, legs, and feet.

Short bones

Bones classified by shape that include the wrist and ankle bones.

Flat bones

Bones classified by shape that include the sternum, shoulder blade, ribs, and skull.

Irregular bones

Bones classified by shape that include the vertebrae, hip, and facial bones.

Projections

Bone markings that serve as sites of muscle and ligament attachment, such as the trochanter, condyle, ramus, and tuberosity.

Depressions and holes

Bone markings that allow for the passage of nerves and blood vessels, such as fissures and foramina.

Diaphysis

The bone shaft consisting of compact bone surrounding the medullary cavity.

Epiphyses

The bone ends consisting of compact bone, spongy bone, and articular cartilage.

Epiphyseal line

The remnant of childhood bone growth located between the diaphysis and epiphyses.

Periosteum

The outer bone covering that contains nerves and blood vessels and provides anchoring points for tendons and ligaments.

Endosteum

The tissue membrane that covers the trabeculae of spongy bone.

Red Bone Marrow

Tissue responsible for blood cell production.

Yellow Bone Marrow

Tissue responsible for triglyceride storage.

Osteon

The structural unit of compact bone oriented parallel to the length of bone.

Lamellae

Layers within an osteon with collagen fibers oriented in alternating directions and sacrificial bonds that break on impact to prevent fractures.

Central canal

The core of an osteon that contains blood vessels and nerve fibers.

Lacunae

Small cavities located between lamellae.

Canaliculi

Hair-like canals that connect lacunae to each other and to the central canal.

Interstitial lamellae

Layers of bone that fill the gaps between osteons.

Circumferential lamellae

Layers of bone around the circumference of the diaphysis, deep to the periosteum, that resist bone twisting.

Perforating canal

Canals oriented at $90^{\circ}$ to the central canal that connect blood and nerve supply from the periosteum to the central canal and medullary cavity.

Trabeculae

The honeycomb-like structural units of spongy bone.

Osteogenic cells

Mesenchymal stem cells that differentiate into osteoblasts or bone lining cells.

Osteoblasts

Cells responsible for bone formation that secrete the organic material called osteoid.

Osteoclasts

Cells responsible for bone resorption.

Osteocytes

Cells found in lacunae that maintain bone and secrete hydroxyapatite for bone hardness.

Intramembranous ossification

The process of bone development that forms the clavicles and skull by depositing and calcifying osteoid tissue.

Endochondral ossification

The process of bone development that forms long bones by replacing hyaline cartilage with osseous tissue.

Interstitial growth

The process of bone lengthening where bone replaces inner epiphyseal plate cartilage.

Appositional growth

The process of bone widening and thickening where osteoblasts secrete osteoid on the outer surface while osteoclasts resorb bone from the inner surface.

Calcium homeostasis

The balance of calcium in the blood, typically maintained at $9-11\,mg/100\,ml$.

Parathyroid hormone (PTH)

Hormone released when blood $Ca^{2+}$ levels fall, causing osteoclasts to degrade bone matrix and release calcium into the blood.

Hypercalcemia

A condition defined by high blood calcium levels resulting in deposits of calcium salts in blood vessels and kidneys.

Hypocalcemia

A condition defined by low blood calcium levels causing fatigue and impaired nerve and muscle function.

Osteomalacia

A condition in adults where bones become thin, soft, and weak due to insufficient vitamin D or calcium.

Rickets

A disease in children caused by vitamin D deficiency that results in bowed legs and abnormal softness of bones.

Osteoporosis

A bone disease where osteoclasts are more active than osteoblasts, leading to increased risk of fractures.

Calcitriol

The active form of vitamin D necessary for bone deposit.

Wolff’s Law

The principle stating that bones remodel in response to mechanical demands and stress.

Nondisplaced fracture

A fracture where bone ends retain their normal position.

Displaced fracture

A fracture where bone ends are out of normal alignment.

Open (compound) fracture

A fracture where the broken bone penetrates the skin.

Comminuted fracture

A fracture where the bone is broken into three or more pieces.

Greenstick fracture

An incomplete fracture where one side of the shaft breaks and the other side bends.

Hematoma

The first stage of bone fracture repair where a mass of clotted blood forms at the fracture site.

Bony callus

The third stage of fracture repair where spongy bone forms to join the broken ends.