What causes Appositional growth?
The process of appositional growth occurs when the cartilage model also grows in thickness due to the addition of more extracellular matrix on the peripheral cartilage surface, which is accompanied by new chondroblasts that develop from the perichondrium.
What is appositional bone growth?
Appositional growth is the increase in the diameter of bones by the addition of bony tissue at the surface of bones. Osteoblasts at the bone surface secrete bone matrix, and osteoclasts on the inner surface break down bone.
Where does intramembranous ossification occur?
bones
The direct conversion of mesenchymal tissue into bone is called intramembranous ossification. This process occurs primarily in the bones of the skull. In other cases, the mesenchymal cells differentiate into cartilage, and this cartilage is later replaced by bone.
What is a periosteal bud?
n. A vascular connective tissue bud from the perichondrium that enters the cartilage of a developing long bone and contributes to the formation of a center for ossification.
What are the 6 major steps in endochondral ossification?
Terms in this set (6)
- Cartilage enlarges; Chondrocytes die.
- blood vessels grow into perichondrium; cells convert to osteoblasts; shaft becomes covered with superficial bone.
- more blood supply and osteoblasts; produces spongy bone; formation spreads on shaft.
- Osteoclasts create medullary cavity; appositional growth.
Does bone do Interstitially or Appositionally?
In endochondral ossification, bone develops by replacing hyaline cartilage. Activity in the epiphyseal plate enables bones to grow in length (this is interstitial growth). Appositional growth allows bones to grow in diameter. Remodeling occurs as bone is resorbed and replaced by new bone.
What is a periosteal reaction?
It is most often identified on X-ray films of the bones. A periosteal reaction can result from a large number of causes, including injury and chronic irritation due to a medical condition such as hypertrophic osteopathy, bone healing in response to fracture, chronic stress injuries, subperiosteal hematomas, osteomyelitis, and cancer of the bone.
What is the periosteum?
The periosteum that covers the outer surface of the bones of the skull is known as the “pericranium”, except when in reference to the layers of the scalp. The word periosteum is derived from the Greek Peri-, meaning “surrounding”, and -osteon, meaning “bone”.
What is the function of the periosteum after a fracture?
After a bone fracture, the progenitor cells develop into osteoblasts and chondroblasts, which are essential to the healing process. As opposed to osseous tissue, the periosteum has nociceptive nerve endings, making it very sensitive to manipulation. It also provides nourishment by providing the blood supply to the body from the marrow.
What is the fibrous layer of the periosteum made of?
The periosteum consists of an outer fibrous layer, and an inner cambium layer (or osteogenic layer). The fibrous layer is of dense irregular connective tissue, containing fibroblasts, while the cambium layer is highly cellular containing progenitor cells that develop into osteoblasts.