Face, jaws, mouth: part 2 Flashcards
describe hyaline cartilage
It is the most common type of cartilage, present in the nose, tracheal rings, the larynx, the articular rings on the bronchi, the ventral ends of the ribs and the articulating surfaces of the long bones
What is cartilage and how is it made?
- Strong, flexible and semi rigid supporting tissue
- withstand compression forces and yet it can bend
- made by chondroblasts and chondrocytes
- ECM rich 10% Aggrecan, 75% water and a mix of collagen fibres
What are the three types of primary cartilage?
- Hyaline
- Fibrocartilage
- Elastic cartilage
Describe the three types of cartilage
Hyaline - most common has a glassy appearance
Fibrocartilage - tendon insertions and intervertebral discs: reinforced with collagen bundles
Elastic cartilage - external ear and epiglottis: flexible and resilient - has elastic fibres
What is cartilage for?
1) To form the supporting framework of some organs, such as the walls of airways (nose, trachea, larynx and bronchi), where it prevents collapse
2) To form the articulating surface of bones
3) To form the template for the growth and development of long bones and most of the rest of the foetal skeleton (where gradually replaced by bone)
describe cells of cartilage - Chondroblast and chondrocyte
ECM secreted by Chondroblasts, found in covering layer of cartilage. Once trapped inside mature into chondrocytes - can divide to form nests of 2-4 cells. Matrix enclosed compartments called lacunae. Chondrocytes large secretory cells with ER
What does the surface of most cartilage consist of?
dense irregular connective tissue perichondrium
What about the outer layer of cartilage?
contains lots of collagen producing fibroblasts and a layer contains chondroblasts
What is unique about cartilage?
is unlike other connective tissue - AVASCULAR
describe the growth 2 mechanisms
Interstitial growth - chondrocytes grow and divide lay down matrix inside the existing cartilage - developmental
Appositional growth - new surface layers of matrix are added to pre-existing matrix by new chondroblasts from the perichondrium
What is meckel’s cartilage?
Cartilage of 1st arch, the mandible itself is preceded by meckel’s cartilage. Rod of cartilage around 6th week IUL. Extends from the otic capsule bony capsule of developing inner ear) to a midline symphysis
What is osteogenesis?
Process of laying down new bone material by osteoblast
What are the ossification pathways?
a) formation of the skeleton through intramembranous (a) and endochondral (b) ossification
Describe the mandibular secondary cartilages
Condylar
- appears 10-12 weeks IUL
Coronoid
- appear 14-16 weeks IUL
- disappear before birth
Symphyseal
- appear 16 weeks
- disappear 1st year after birth
Secondary (Growth) cartilages
Differ from primary cartilage:
- not part of primary (catilaginous) skeleton
- fibrocartilage (not hyaline cartilage)
- appositional growth rather than interstitial growth
Produce (type of) Endochondral Ossification (Greek - endon within chondros-cartilage)
