Bone Path Flashcards
What is achondroplasia
absence of cartilage development
what is chondroplasia
disordered cartilage development
what is brachycephalia
shortening of the head
what is brachygnathia
shortening of the jaw
what is palatoschisis
cleft palate
what is prognathia
abnormal projection of the jaw
what is kyphosis
abnormal dorsal curvatiure of the spine
what is lordosis
abnormal ventral curvature of the spine
what is scolliosis
lateral deviation of the spinal collum
what is amelia
absence of one or more limbs
what is hemimelia
absence of the distall half of the limb
what is micromelia
presence of abnormally small limbs
what is peromelia
congenital deformity and shortening of the limbs
what is phocomelia
absence of proximal part of one or more limbs
what is adactyly
absence of the digit
what is dactylomegaly
abnormally large digits
what is ectdactyly
partial or complete absence of a digit
what is polydactyly
supernumerary digits
what is polypodia
supernumerary feet
what is syndactyly
fusion of digits
what is diprosopus
incomplete duplication of the head
what is dicephalus
duplication of the head
what is cyclopia
presence of a single orbit and eye
what is spinabifida
defective closure of the dorsal vertebral laminae in a segment of the spinal column
what is perosomus elumbus
agenesis of the lumbosacral spinal cord and vertebrae
what are block vertebrae
improper segmentation of the somites in the embryo causing partial or complete fusion of adjacent vertebrae
what is the axial skeleton
includes the head, ribs, vertebrae and sternum
what is the appendicular skeleton
the bones of the thoracic and pelvic limbs
what is bone derived from?
mesenchyme
what type of ossification forms flat bones
intramembranous
calcium is deposited around the extracellular matrix leading to the formation of trabeculae
the initial fibrous membrane becomes periosteum and spaces between the trabeculae are filled with bone marrow
What type of ossification forms long bones
endochondrial ossification
replacement of cartilage with bone
osteoblasts form compact bone at the diaphysis
the central cartilage cells enlarge and burst which when calcified become the marrow cavity
What are osteoblasts
form osteoid for bone deposition
plump, cuboidal, basophilic cells when active
flattened and lining the bone surface when inactive
what are Osteocytes
osteoblasts which have lost their ability to produce osteoid, they reside in the bone matrix in lacunae
what are osteoclasts
responsible for bone resorption
are large, multinucleated cells with eosinophilic cytoplasm which sit on the bone surface with a ruffled brush border
what are the two types of bone
lamellar (layered bone) which has 2 types:
- spongy/ trabecular bone has large spaces filled with marrow, found in flat bones and at the epiphyses of long bones
- compact bone has few spaces and is seen at the diaphysis of long bones over a layer of trabecular bone
woven bone is newly formed bone with a disorganised arrangement and is yet to be organised into lamellar bone
Describe the process of bone reabsorption
the osteoclasts create an acidic environment on the bone surface
hydrogen and bicarbonate are produced using water and carbon dioxide via carbonic anhydrase
hydrogen ions are actively pumped out onto the surface of the bone, this acidity induces demineralisation
How long does osteoid take to mineralise
5-10 days, is more eosinophilic than mineralised osteoid
How is bone deposition and reabsorption regulated
parathyroid hormone activates osteoclasts
calcitonin inhibits osteoclasts
vitamin D3 stimulates osteoclastic activity
How does the bone respond to injury
- growth arrest lines - transverse calcified structures which lie parallel to the growth plate
- Growth retardation lattice - persistence of non-properly formed areas of ossification at the growth plate and persistence of non-mineralised cartilage
- woven bone seen at sight of fractures
- resting lines - longitudinal, straight basophilic line
- reversal lines - scalloped lines show edges of past osteoclast resorption
Describe the features of bone growth
- endochodrial ossification occurs at growth plates where chondrocytes proliferate, enlarge and create a trabecular network which is then calcified. Osteoclasts and blasts then move in to remodel
- intramembranous ossification occurs in condensed mesenchymal tissue
