Lecture 17 - Skeletal System Flashcards
What are the four most common types of bone into which most bones can be classified
Long
Short
Flat
Irregular
What is the major division of the skeleton?
Axial
Appendicular
What are accessory bones?
These are evolutionary relics that appear as anomalies
What are sesamoid bones?
These are bones that are embedded in tendon
Eg. Patella
What are pneumatic bones?
These are bones that have been hollowed out during development to reduce the weight.
Eg. The skull and the sinuses of the face
What are the articular surfaces of the bone?
These are the regions that interact with other bones
What are the general features of long bones?
- Proximal and Distal end
- Shaft
- Articular surfaces
What is the function of the periosteum?
Rich blood and nerve supply
What are the two layers of the periosteum?
Inner: osteogenic
Outer: fibrous
What is the function of the endosteum?
Osteogenic
What are the different densities of bone?
Cancellous: spongy, holes
Compact: very dense
What and where is the medullary cavity?
It is the cavity in the shaft of the bone
Red and yellow bone marrow are found here
What is the different between red and yellow marrow?
Red: hematopoetic
Yellow: present in older people
There are no nerves inside the bone, yet when a bone is fractured, it is painful. Account for this
The pain comes from the tearing of the periosteum, which has a rich nerve supply
Differentiate between increasing width and length of bone
Increasing the width: inner periosteum and the endosteum
Increasing length: epiphysial line
What is another name for compact bone?
Cortical
What is important about trabecular bone?
What is meant by this term?
Capable of resisting static forces, due to:
- Special orientation of the spongy bone
What are static forces?
Weight bearing forces
What is intramembranous ossification?
This is when the bone forms in membrane
Eg. The skull
What are the structural layers of the skull bone?
Outer compact
Spongy bone
Inner compact
What is the name of the triangular hole in the skull present at birth?
Fontanelle
What is endochondral ossification?
This is when the bone forms in cartilage
What are the three types of cartilage?
Hyaline
Fibro
Elastic
How do most bones of the body form?
After about 2 months, the foetus has bones that have grown out of hyaline cartilage
Endochondral ossification
Where does ossification first occur in bone?
At the primary centres in the shaft of the cartilage precursor
Describe replacement of cartilage with bone
At the primary centre in the centre of the cartilage, replacement of cartilage with bone occurs, extending towards the ends
What is the name for the shaft of the developing bone?
Diaphysis
What is the name of the ends of the developing bones?
Epiphysis
What is the name of the site of high metabolic activity and remodelling? Where is it?
Metaphysis
Forms the boundary of the diaphysis at each end
Is the cartilage of the developing bone completely replaced with bone?
Yes, apart from at the Articular cartilage
The cartilage at the epiphysial plate is replaced after growth
What are where is the nutrient foramen
Located in the middle of the shaft of the bone
Artery delivers bone forming cells
Which cells are important for bone formation?
Osteoblasts: forming bone
Osteoclasts: remodelling bone
What is the name of the cartilage that remains on the bone forever?
Articular cartilage
What disorders can occur to the development of bone?
Achondroplasic dwarfism
Spontaneous mutation causes the long bones to stop growing. Other bones are unaffected
Chondrocytes fail to mature and enlarge
Why are epiphyses clinically important?
- indicate that growth is still occuring
- if damaged, there may be problems with growth
- indicate the age of an individual in a forensic setting
- may be confused with a fracture
What are the four types of arteries that deliver blood to bone?
Nutrient
Periosteal
Metaphysical
Epiphyseal
What is clinically significant about the blood supply to bones?
End arteries: the only supply to the bone
If blocked, e bone receives no blood
What are the two different types of fracture?
Simple fracture: no breaking through skin
Compound fracture: bone breaks through skin
