MSK Glossary Flashcards
What developmental origin do bones, connective tissue and skeletal muscle have?
Mesoderm of the trilaminar disc
What are the functions of bone?
Support
Protection
Metabolic (calcium and phosphate)
Storage (important growth factors and cytokines)
Movement
Haematopoiesis (in children, long bones are important for this; in adults, mainly the pelvis, skull, vertebrae and the sternum)
What type of muscle is skeletal muscle?
Striated, under voluntary control
What are the functions of skeletal muscle?
Locomotion Posture Metabolic Venous return Heat production Continence
What are the functions of the fascia?
It’s a sheet of connective tissue
To envelop groups of muscles and divide body parts into anatomical compartments
Some are very tough eg fascia lata in thigh, so protective
Where is hyaline (articular) cartilage found?
Ends of bones
How is fibrocartilage different to hyaline cartilage?
Fibrocartilage has more collagen so it is tougher
It plays an important role with regard to shock absorption and also increasing bony congruity at joints (congruity = creating a complementary shape of bony surfaces to improve stability), eg. the menisci of the knee
Where are synovial membranes found and what does it do?
Found within joints, bursae and tendon sheaths.
It produces synovial fluid which lubricates the joints
What are some cells found in bones?
Predominantly osteocytes, osteoblasts and osteoclasts. There are also fibroblasts, macrophages, mast cells and adipocytes.
What is hydroxyapatite?
Calcium phosphate (CaPO4)
It mineralises the extracellular matrix, differentiating bone from other connective tissues
It confers rigidity to the bone
What are some non-cellular components of bone?
Hydroxyapatite Collagen (main fibre type) Water Glycosaminoglycans Proteoglycans Insignificant amounts of elastin
What gives bone its mechanical strength? How?
The calcium phosphate confers great compressive strength and the collagen confers great tensile strength to the bone.
You can think of this as being like steel-reinforced concrete with the collagen being the steel (tensile strength) and the calcium phosphate being the concrete (compressive strength).
What do osteoblasts do?
Synthesise new bone.
They migrate over the matrix and synthesise and deposit osteoid.
The osteoblasts then deposit calcium phosphate into the osteoid to make bone.
What does osteoid do?
It is a matrix protein of bone
Osteoid contains collagen as its major protein and specialised proteins in smaller quantities, including osteocalcin and osteopontin
What are osteoclasts? What do they do?
Multinucleate cells formed by fusion of progenitor cells of the monocyte/macrophage lineage. They migrate over the surface of the bone matrix and secrete acidic chemicals to dissolve it, forming a pit on the surface of the cortical bone.
As an osteoclast becomes active, the surface that is in contact with the bone becomes ruffled. This increases the surface area for absorption of minerals such as calcium and phosphate. The minerals in their ionic form are absorbed into the osteoclast, which later releases them into the extracellular fluid, from where they enter the blood. The process of bone breakdown and mineral uptake by the osteoclasts is known as resorption.
