Chapter 17
The skeletal system
Glossary
Adduction: movement towards the body’s midline.
Anatomy: the study of body structures and their relation to other structures in the body.
Ball-and-socket joint: a synovial joint in which the rounded surface of one bone fits within the
cup-shaped depression of the socket of the other bone.
Calcification: deposition of mineral salts in a framework formed by collagen fibres in which tissue
hardens.
Cancellous: a type of structure as seen in spongy bone tissue; resembles a latticework structure.
Cartilage: strong, tough material on the bone ends that helps to distribute the load within the joint;
the slippery surface allows smooth movement between the bones; a type of connective tissue.
Cartilaginous joint: a joint where the bones are held together tightly by cartilage; little movement
occurs in this joint. This joint does not have a synovial cavity.
Collagen: a protein that makes up most of the connective tissue.
Condyloid joint: a synovial joint that allows one oval-shaped bone to fit into an elliptical cavity of
another.
Diaphysis: the shaft of a long bone.
Epiphysis: the ends of long bone.
Fibrous joint: a type of joint that allows little or no movement.
Flexion: movement where there is a decrease in the angle between two bones.
Fracture: a break in a bone.
Gliding joint: a synovial joint whose articulating surfaces are usually flat, allowing only one side-toside or back-and-forth movement.
Haematopoiesis: the formation and development of blood cells in the bone marrow after birth.
Hormone: the secretion of endocrine cells that have the ability to alter the physiological activity of
target cells in the body.
Insulin-like growth factor (IGF): produced by the liver and other tissues, this is a small protein that
is produced in response to human growth hormone.
In utero: within the uterus.
Lacuna: a small, hollow space found in the bones where osteocytes lie.
Lamellae: rings of hard, calcified matrix found in compact bones.
Ligaments: tough fibrous bands of connective tissue that hold two bones together in a joint.
Macrophages: cells that engulf and digest cellular debris and pathogens.
Marrow: a sponge-like material found in the cavities of some bones.
Mesenchyme: embryonic connective tissue from which nearly all other connective tissue arises.
Metaphysis: the aspect of long bone that lies between the diaphysis and the epiphysis.
Ossification: the formation of bone, sometimes called osteogenesis.
Ossicles: small bones of the middle ear – the malleus, stapes and incus.
Osteoblasts: cells that arise from osteogenic cells; these cells participate in bone formation.
Osteoclasts: large cells that are associated with absorption and removal of bone.
Osteocytes: mature bone cells.
Periosteum: membrane covering bone consisting of osteogenic cells, connective tissue and
osteoblasts. This is vital for bone growth, repair and nutrition.
Pivot joint: a joint where a rounded or conical-shaped surface of a bone articulates with a ring
formed partly by another bone or ligament.
Remodelling: replacement of old bone by new.
Resorption: absorption of what has been excreted.
Saddle joint: a synovial joint articulates the surface of a bone that is saddle shaped on the other
bone that is said to be shaped like the legs of the rider.
Spongy (cancellous) bone: bone tissue comprised of an irregular latticework of thin plates of bone
known as trabeculae. Some bones are filled with red bone marrow and these are found in short, flat
and irregular bones as well as the epiphyses of long bones.
Synovial cavity: the space between the articulating bones of a synovial joint, filled with synovial
fluid.
Synovial fluid: the sections of the synovial membranes that lubricate the joints and nourish the
articular cartilage.
Trabeculae: a network of irregular latticework of thin plates of spongy bones.