Introduction to Bone and Soft Tissue Flashcards
(41 cards)
What makes up the MSK system?
Bone
muscle
connective tissue (tendon, ligaments and cartilage)
What is a joint?
a point at which 2 separate bones meet
How many bones are there in the adult human skeleton?
206 bones (+sesamoids)
How many bones are there in the a child’s human skeleton?
270 bones
What two skeletons is the human skeleton split into?
Appendicular and axial skeleton
See diagram 4/33
What does the appendicular skeleton compose of?
pectoral girdle, upper and lower limbs, pelvic girdle
What does the axial skeleton compose of?
Cranium, vertebral column, rib cage
What are the 5 functions of the skeleton?
- Support - helps you stand up
- Protection - protects vital organs
- Movement - works with muscles so you can get around
- Mineral Storage - stores Calcium and phosphate
- Produces blood cells
How do bones develop in utero?
Intramembranous (Mesenchymal cells -> bone) — flat bones
Endochondral (Mesenchymal -> cartilage -> bone) — long bones
What does intramembranous ossification form?
flat bones of skull, clavicle and mandible
How does intramembranous ossification form bone?
(Bone development from fibrous membranes)
With mesenchymal cell template
- Condensation of mesenchymal (stem) cells which differentiate into osteoblasts - ossification centre forms
- secreted osteoid traps osteoblasts which become osteocytes
- Osteoid calcifies and forms slender, needle-like structures of spongy bone called spicules, which aggregate in the form of small supporting beams or trebeculae. Trabecular matrix and periosteum forms
- (lamellar) compact bone develops superficial to cancellous bone. Crowded blood vessels condense into red bone marrow
(See diagram 7/33)
What is osteoid?
organic part of the bone, consisting of collagen fibres
What is the periosteum?
fibrous sheet that covers bone
What is woven bone characterised by?
organisation of collagen fibres and is mechanically weak
What is lamellar/compact bone?
has regular, parallel alignment of collagen in the form of sheets or lamellae and is mechanically quite strong
What does Endochondral ossification form?
long bone from a hyaline cartilage model
which takes longer, intramembranous ossification or endochondral ossification?
endochondral ossification
What is the primary ossification centre in endochondral ossification?
diaphysis
forms the centre of long bones
What is the secondary ossification centre in endochondral ossification
epiphysis
forms the end of long bones
Describe the formation of bones via endochondral ossification.
Process begins in the developing fetus.
Around the 8th week of development, chondroblasts begin secreting a cartilaginous matrix that will form the hyaline cartilage model for bone development. Chondrocytes are trapped in lacunae and a perichondrium surrounds the model.
As chondrocytes enlarge, the matrix begins to calcify and chondrocytes begin to die as nutrients cannot diffuse through the newly-formed calcified matrix.
Stem cells within the perichondrium divide to form osteoblasts and a compact bone collar is formed around the calcified cartilage shaft.
- Bone collar formation
- Cavitation
- Periosteal Bud Invasion into the core of the cartilaginous shaft, forming a primary ossification centre
- Diaphysis Elongation
- Epiphyseal Ossification
(see diagram 9/33)
What is the name of the junction between the primary and secondary ossification centres?
epiphyseal plate
this is where the growth of bones occur after birth
When are most primary ossification centres formed by?
12th week of development
What are bones made up of?
cells
matrix
What is the osteogenic cell?
bone ‘stem cell’ - precursor to all of these bone cells
