Anatomy of Bones & Joints (S1)

organic matrix of fibrous connective tissue and mineral salts

Articulations - connecting one or more bones to another

Joint surface - highly specialised tissue designed to withstand loads without failing

• long (humerus) • short (carpals) • flat (frontal) • irregular (vertebra) • sesamoid (patella)

• strength (trabechulae for stress + cortical/compact) • flexibility (connective tissue/collagen) • hardness + rigidity (organic salts eg calcium) • light (trabechulae, porous)

Compact bone tends to be thin over edges, thickest at midshaft, denser (5-10% porous) whereas, spongy bone are 50-90% porous, towards the centre of bone.

Eg. Skull - air filled sinuses, with single and many spaces.

• protective • contribute to mobility • attachments for discs, ligaments + muscles • supplies nutrients to body -> make RBCs • stores calcium + releases in response to body’s need

• process during foetal development in creating bone tissue (eg long, short, irregular) • long bones elongate • partially minerlizaed cartilaginous matrix formed at the growth plate • resorbed and replaced by woven bone • then subsequently remodelled into lamellar bone

• different to endochondral ossificaiton, this one forms flat bones • not from the cartilage template formed first • bone lining cells differentiate to form mature osteoblasts • osteoblasts secrete osteiod (unmineralised organic matrix) • osteoid undergoes maturation • mineralisation: calcium and phosphate is deposited within the organic matrix • remodelling - osteoclasts resoprtion while osteoblast formation - ongoing process

• fibrous • NO movement - eg sutures in skull, bound closely by fibrous tissue • cartilaginous • no/little movement, intervertebral disc • synovial • freely mobile, eg. knee, hip etc (some mixed joints eg sacroiliac)

• suture (seam) • a joint with a thin fibrous layer that binds skull bones • syndesmosis (band) • bigger space than suture, fibrous tissue arranged as a sheet or in a bundle called ligament eg. tibiofibular • gomphosis (bolt) • consists of a peg and socket, such as the root of a tooth which is anchored into a socket by its fibrous ligament

• synchondrosis • hyaline cartilage is the connective tissue, eg. epiphyseal plate between epihysis and diaphysis of bones • symphysis • connecting material is fibrocartilage eg. pubic symphysis

• articular surfaces covered with articular hyaline cartilage for lubrication and absorption of impacts • capsule contains synovial fluid -> limits movement • capsule lined by synovial membrane which produces lubricating syovial fluid

• ball and socket (shoulder, hip) • hinge (elbow) • gliding (intercarpal) • saddle (thumb) • pivot (neck) • condyloid (wrist/radiocarpal)