Bones and Joints Flashcards
What is the function of bones
support, protection, mineral store and blood formation
what types of bones are there
flat, sutural, short, irregular, sesamoid and long
what are the components of bones
compact v spongey blood vessels medullary cavity bone marrow membranes - periosteum (outside) + endostium
what is the structure of compact/cortical bone
circular structures - osteons/ haversian system
central haversian canal
horizontal perforating/volkamanns canals
osteocytes and concentric rings of bone matrix (lamellae) around haversian canal
what are the components of osteons
central haversian canal
rings of lamella bone
osteocytes
what is the structure of spongey/trabecular bone
less dense than compact bone, porous
network of lamellated trabeculae filled w bone marrow
no haversian system
what cells are bones composed of
osteoclasts
osteoblasts
osteocytes
what is in the ECM of bones
hydroxyapatite crystals (calcium phosphate) collagen (type 1) water
what is the function of hydroxyapatite
makes bone stiff + able to support structures
high strength under compression
what is the function of collagen
gives bone flexibility + reduce risk of fracture
high strength under tension
how is bone a dynamic tissue
- fracture healing
- mechanical adaptation
what are osteoclasts, describe them and function
large multinucleated cells derived from haematopoietic stem cells
found on bone surface
function - resorb bone matrix
ruffled border - releases acid to dissolve bone matrix
howship’s lacunae - resorption pits
what are osteoblasts
immature bone cells created from osteopregenitor cells in peri and endosteum function - produce bone matrix = osteoid and initiate calcification become osteocytes once surrounded by matrix
(on outisde in histology)
whats the function of osteoblasts
produce bone matrix = osteoid and initiate calcification
whats the function of osteoclasts
resorb bone matrix
ruffled border - releases acid to dissolve bone matrix
what are osteocytes
mature bone cells found inside lacunae
numerous processes lying in canaliculi
what are canaliculi
connect lacunae to eachother allow communication between cells
describe the ECM for bones
minerals, collagen and water
strongly cross-linked & large ‘gaps’ within fibres
gaps provide space fro crystals
what is osteoporosis
resorption > formation
what is pagets disease
increased resorption/formation
osteopetrosis
decreased resorption
what is bone mass controlled by
genes and environment
what is ossification
bone formation
what are the 2 types of ossification
endochondral
intramembranous
explain endochondral ossification
bone forms as cartilage model first blood vessels invade cartilage cartilage replaced w bone cartilage remains in epiphyseal growth plate growth plate eventually ossifies
explain intramembranous ossification
no cartilage model
mesenchymal cells develop into osteoprogenitor cells that develop into osteoblasts that deposit bone
residual mesechymal cells develop bv and marrow
this occurs in adult bone also
what are the two types of bone growth
appositional and interstitial
what is appositional growth
bone grows in thickness, transverse plane
what is interstitial growth
bone grows in length
what is a joint
union between 2 or more rigid components (bone or cartilage)
articulation
what types of joints are there
fibrous
cartilaginous
synovial
what are fibrous joints and examples
dense fibrous connective tissue high tensile strength little movement cranial structures periodontal ligament (teeth) interosseus membranes, between bones
what are cartilaginous joints and what types are there
layers of cartilage
sychondroses (primary) and symphyses (secondary)
describe synchrondroses joint
allow for bone growth (endochondral ossification)
disappear in adults
no movement
- hyaline cartilage
describe symphyses joint
secondary cartilaginous doesnt ossify w age found in midline of body limited movement e.g. in vertebrae
what are synovial joints, name their common features
greatest movement fibrous capsule synovial membrane articular cartilage synovial cavity
what are the types of synovial joints
hinge pivot ellipsoid ball and socket plane saddle
what affects joint stability
shape of joint surfaces
fibrous capsule and ligaments
muscles
Which part of synovial joints produces the synovial fluid and whats it purpose
synovial membrane - reduces friction between the articular cartilages during movement
why are flexion and extension opposite in arm and e
due to limb rotation in development of child
upper limb - lateral rotation
lower limn - medial rotation + more rotation
why is limb rotation and evolutionary process important
more efficient weight bearing and locomotion
joints have rich blood + nerve supply, what is common around joints
anastomoses (joining of vessels)
blood flow can take alternative routes if a vessel is blocked
what is hiltons law
the nerve supplying a muscle that crosses a certain joint, also innervates this joint
what colour is the densest material in a CT scan
white
