Anatomy: Skeletal System Flashcards

Question 1

Define Skeletal System.

Accepted Answer

The organ system made of bones, cartilage, ligaments and joints that supports the body, protects organs, enables movement, stores minerals and produces blood cells.

Question 2

Define Axial Skeleton.

Accepted Answer

The 80 bones along the body's central axis: the skull, the ossicles of the middle ear, the hyoid, the vertebral column and the thoracic cage.

Question 3

Define Appendicular Skeleton.

Accepted Answer

The 126 bones of the limbs and of the pectoral and pelvic girdles that attach the limbs to the axial skeleton.

Question 4

What is Osteoblast?

Accepted Answer

A bone-forming cell that secretes osteoid, the collagen-rich organic matrix, and helps mineralise it; once surrounded by matrix it becomes an osteocyte.

Question 5

What is Osteocyte?

Accepted Answer

A mature bone cell trapped in a lacuna within mineralised matrix, which senses mechanical strain and signals other bone cells to maintain the surrounding tissue.

Question 6

What is Osteoclast?

Accepted Answer

A large, multinucleated cell derived from blood monocytes that dissolves bone matrix using acid and enzymes, releasing calcium and phosphate into the blood.

Question 7

What is Hydroxyapatite?

Accepted Answer

The calcium phosphate mineral crystal that makes up most of bone's inorganic matrix and gives bone its hardness and resistance to compression.

Question 8

Define Osteon (Haversian System).

Accepted Answer

The structural unit of compact bone: concentric rings of matrix called lamellae surrounding a central canal that carries blood vessels and nerves.

Question 9

Define Compact Bone.

Accepted Answer

Dense bone tissue built from tightly packed osteons that forms the hard outer layer of all bones and the thick walls of long bone shafts.

Question 10

Define Spongy Bone.

Accepted Answer

Lightweight bone tissue made of a lattice of thin plates called trabeculae, found inside the ends of long bones and within flat bones, with red marrow in its spaces.

Question 11

What is Periosteum?

Accepted Answer

The tough, two-layered membrane covering the outer surface of bone except at joints, supplying blood vessels and nerves and containing cells that build new bone.

Question 12

Define Medullary Cavity.

Accepted Answer

The hollow space inside the shaft of a long bone, lined by endosteum, that contains yellow marrow in adults and red marrow in young children.

Question 13

What is Diaphysis?

Accepted Answer

The long, tubular shaft of a long bone, made of a thick collar of compact bone surrounding the medullary cavity.

Question 14

What is Epiphysis?

Accepted Answer

The expanded end of a long bone, made of spongy bone covered by a thin shell of compact bone, with articular cartilage where it forms a joint.

Question 15

Define Epiphyseal Plate.

Accepted Answer

A disc of hyaline cartilage between the diaphysis and epiphysis of a growing bone, where new cartilage is added and replaced by bone so the bone lengthens.

Question 16

Define Red Bone Marrow.

Accepted Answer

Soft tissue in the spaces of spongy bone that carries out hematopoiesis, producing red blood cells, white blood cells and platelets.

Question 17

Define Yellow Bone Marrow.

Accepted Answer

Fat-rich marrow that fills the medullary cavities of adult long bones, stores energy as triglycerides and can convert back to red marrow after severe blood loss.

Question 18

What is Hematopoiesis?

Accepted Answer

The production of all blood cell types from hematopoietic stem cells, which after birth takes place in red bone marrow.

Question 19

Define Intramembranous Ossification.

Accepted Answer

Bone formation directly within a sheet of fibrous connective tissue, without a cartilage model first; it forms the flat bones of the skull and most of the clavicle.

Question 20

Define Endochondral Ossification.

Accepted Answer

Bone formation in which a hyaline cartilage model is laid down first and then gradually replaced by bone; it forms most bones below the skull.

Question 21

Define Bone Remodeling.

Accepted Answer

The lifelong cycle in which osteoclasts remove old bone and osteoblasts replace it, letting the skeleton repair microdamage, adapt to load and regulate blood calcium.

Question 22

Define Long Bone.

Accepted Answer

A bone that is longer than it is wide, with a shaft and two ends, acting as a lever for movement; most limb bones belong to this group.

Question 23

Define Sesamoid Bone.

Accepted Answer

A small, rounded bone that develops inside a tendon, protecting the tendon from wear and improving the mechanical leverage of its muscle.

Question 24

What is Suture?

Accepted Answer

An immovable fibrous joint where the edges of two skull bones interlock, held together by a thin layer of dense connective tissue.

Question 25

Define Synovial Joint.

Accepted Answer

A freely movable joint where bone ends are covered by articular cartilage and enclosed in a fluid-filled capsule lined by a synovial membrane.

Question 26

Define Articular Cartilage.

Accepted Answer

The smooth layer of hyaline cartilage covering the bone ends inside a synovial joint, which reduces friction and absorbs shock during movement.

Question 27

What is Ligament?

Accepted Answer

A band of dense regular connective tissue that connects bone to bone, stabilising a joint and limiting movements that would damage it.

Question 28

Define Vertebral Column.

Accepted Answer

The flexible spine of 26 bones in adults (7 cervical, 12 thoracic, 5 lumbar, the sacrum and the coccyx) that supports the head and trunk and protects the spinal cord.

Question 29

Define Pectoral Girdle.

Accepted Answer

The clavicle and scapula on each side, which attach the upper limb to the axial skeleton at a single joint and give the shoulder its wide range of motion.

Question 30

Define Pelvic Girdle.

Accepted Answer

The two hip bones, each formed by the fused ilium, ischium and pubis, which attach the lower limbs to the sacrum and transfer body weight to the legs.

Question 31

Define Thoracic Cage.

Accepted Answer

The bony enclosure of the chest formed by the sternum, 12 pairs of ribs with their costal cartilages, and the 12 thoracic vertebrae, protecting the heart and lungs.

Question 32

What is Osteoporosis?

Accepted Answer

A disease in which bone mass and density fall and bone structure weakens, so bones become fragile and break from minor falls or everyday stress.