14 - MSK Bones & Joints Flashcards
(38 cards)
What is bone made of
connective tissue consisting of abundant ECM surrounding widely spaced cells
What does ECM consist of
15% water
30% collagen
55% crystallized mineral salts
What are the four types of cells that maintain bone
osteoprogenitor cells (stem cell –> give rise to osteoblast)
osteoblasts (imamture cell –> lay down collagen and calcium salts to build up bone, turn into osteocyte)
osteocytes (bone cell –> maintain bone tissue)
osteclasts (reabsorb bone to release calcium within it)
What are the types of bone
compact
Spongy
What is compact bone
compact
- 80% of skeleton
- underneath periosteum (living layer of connective tissue - collagen and stem cell)
- strongest type
- arranged in osteons (ring-like) (osteocytes around)
- protection and support (weight/movement)
What is spongy bone
-20% of skeleton
- trabecular or cancellous bone (b/c has physical spaces)
- located deep to compact bone (bone interior) always inside
- arranged in irregular columns called trabeculae (small beams)
- spaces filled with red marrow (between trabeculae)
How is bone formed
cartilage models that are slowly replaced by bone (ossified)
- osteoprgenitors turn into osteoblasts within the ossification centres and calcify the ECM
- starts in ossification centre and spreads out
(primary - middle/shafts, secondary centres - ends of bones)
Where is yellow marrow and red marrow found
medullarly cavity of the diaphysis of long bones (spongy layer): yellow (fat - energy)
epiphysis and metaphysis: red
epiphyseal becomes bone at 25
What is a nutrient formaina
what does it do
hole where nutrient arteries and veins penetrate the bone
feed the medullary cavity
gets cells out
T/F the blood supply can cross the epiphyseal (growth) plate
FALSE
it cannot cross the epiphyseal plate as it is composed of cartilage
T/F the periosteum of the bone is richly innervated
TRUE
The periosteum is the membrane of blood vessels and nerves that wraps around most of your bones
when you fracture a bone, periosteum gives the sensations
How does bone remodelling occur
osteoblasts constantly laying down new bone in response to the forces applied to the bone
(body weight down on bone –> osteoblast line alongside of bone to make bone strong in the direction)
osteoblasts more active in growth years (height), less in adulthood
Osteoclasts nibble away at the calcium, shape and remodel the bone
max bone density @ 20, then slow degredation after
What are the hormones involved in calcium homeostasis
calcitonin
parathyroid hormone
What is the purpose of calcium homeostasis
support nerve and muscle function (to cause contractions
(not to maintain bone density)
Bones serve as a resevoir of calcium
What does calcitonin do
increase calcium deposition in bones to reduce serum levels
(build up bone)
What does parathyroid hormone
increases calcium release from bones (reabsorption to increase serum levels)
promotes activity of osteoclast to help nibble away at calcium and release calcium from matrix (put back into serum) create phorus bone
What are the types of fractures
simple (closed) - does not penetrate the skin
compound (open) - penetrates the skin
What are the common fractures
- Comminuted (multiple splinter, extreme trauma, brittle bones)
- Compression (collapse, osteoporosis, extreme trauma)
- Spiral (rotational force, sports injury from piviting, toddlers because bones still mostly collagen)
- Epiphyseal (rotational force, toddler, sports injury - still cartilage in bone – metiphasis seperates from the etaphysis)
- Depression (blunt forced trauma)
- Greenstick (partial fracture in children, frays like a tree branch)
What are the steps in bone healing (repair)
3 phases (4 steps): reactive, reparative, remodelling
- reactive phase: fracture bone so blood vessels bleed –> creates fracture hematoma, periosteum keeps blood in one spot
- reparative phase:
- recapitualing development (forming bone via cartilage intermediate) –> forms fibrocartilaginous callus
- Stems cells migrate into site of fracture and become chondrocytes
- Osteoblasts come in and lay down collagen (join two bones together) - Reparative phase
- osteoblasts replace cartilage and deposit calcium ontop of it
- wayy too much bone - Bone remodelling phase
- lay down and nibble away bone to reshape
What do ligaments do
- stablaize joints (ie. knee)
- form interosseus membrane between two bones that acts to seperate limb compartments
- acts as site for attachment of muscles
What are ligaments
dense, regular connective tissue consisting mainly of collagen fibers
connects bone to bone
What are the types of ligaments
(tibial) medial collateral ligament
posterior cruciate ligament
(fibular) lateral collateral ligament
interosseous membrane (attachment site)
What is the damage to a ligament
sPrain
collagen fibers laid down by firboblasts –> so never the same again (not the same tension)
What are tendons
dense, regular connective tissue consisting mainly of collagen fibers
