Anatomy - bones Flashcards
Number of bones in the human body
206
Proportion of total body mass comprised by the skeleton
20%
2 parts into which the skeleton is divided and main functions of each part
Axial - mainly protective role
Appendicular - function in movement
Functions of the skeleton
- Protect vital organs
- Provide rigidity for the body
- Provide attachment for muscle
- Manufacture of red blood cells
- Storage of mineral metabolism
What kind of tissue is bone?
Osseous tissue
How much calcium can enter/leave the adult skeleton each day?
0.5g calcium
What % of bone can be recycled each week?
7%
What percentage of bone is water and what does the remainder comprise?
25-30% water
Remainder: inorganic (e.g. calcium and phosphate) and organic (e.g. collagen proteins)
What is the micro structure of bones
Fibrous matrix of collagen fibrils
Tissue fluid and protein polysaccharides interspersed amongst the fibrils
Organic material is impregnated with minerals
Meaning of osteogenic
Relating to the formation of bone
Term for membrane covering bones?
What is the structure of this membrane?
Periosteum
2 layers:
- strong collagenous outer layer
- deeper osteogenic inner layer which produces osteoblasts
Contains capillaries which nourish the bone
Nerve supply
Name of cells which participate in growth and repair of bones?
Osteoblasts
What part of the bone do muscles attach to ?
Periosteum
From what part of the bone does most of the pain from fractures, bruises and shin splints emanate?
Periosteum
What are the key part of the bone (from proximal to distal ends of femur) and what material are they comprised of?
- Articular cartilage
- Proximal epiphysis (spongy bone)
- Epiphyseal line
- Metaphysis (spongy bone)
- Diaphysis (containing medullary cavity)
- Metaphysis
- Distal epiphysis
- Articular cartilage
What parts of the bone are the different types of marrow contained within
Red bone marrow - metaphysis [and epiphysis?]
Yellow bone marrow - Diaphysis (in medullary cavity)
Classifications of bone and example?
- Long bones e.g. humerus
- Short bones - e.g. tarsal and carpal
- Flat bones e.g. sternum, ribs, ilium, scapulae
- Irregular bones e.g. vertebrae, sacrum, pubis, maxilla
- Sesamoid bones e.g. patella
In what part of the skeleton do long bones occur and what is their main function
Appendicular skeleton
Weight bearing and movement
What is the long central shaft of long bones called
What is its structure/what does it contain?
Diaphysis
Outer shell of dense compact bone enclosing a latticework of cancellous bone
Central hollow (medullary) cavity containing yellow marrow (fat storage, bone, cartilage and fat)
Metaphysis
Cancellous bone consists of trabeculae with interstices filled with red marrow (red and white blood cell formation)
What happens to the compact bone surrounding the bone and the trabeculae towards the expanded ends of long bones?
Compact bone thins
Trabeculae arranged along lines of force transmission
What replaces the periosteum at the end of the bone
Hyaline cartilage
What shape are short bones?
Irregular, chunky, roughly cuboidal
What is the structure of flat bones and what function do they perform?
Spongy bone enclosed by two layers of compact bone
Serve as flat areas for muscle attachment and (other than scapulae) enclosing body cavities
Where do sesamoid bones form and what is their purpose
Form in certain tendons
To give a mechanical advantage, to protect underlying surfaces, to reduce friction and wear (e.g. patella).
Reinforce and decrease stress on the tendon. Absorb and redistribute weight bearing forces decrease friction, protect and enhance power production
Types of joint and examples?
- Ball and socket (hip/shoulder)
- Condyloid - similar to ball and socket but less movement across one axis e.g. wrist
- Saddle joint e.g. thumb
- Hinge joint e.g. finger
- Pivot e.g. where humerus meets radius and ulna (radius and ulna can rotate)
What is the process by which bone grows in the embryo called?
What does it involve?
Ossification
Laying down of collagenous matrix:
- In existing connective tissue (intramembranous ossification) e.g. in clavicle or skull bones
- In hyaline cartilage (intracartilaginous ossification) e.g. in short bones
Followed by laying down of mineral salts in an organic matrix
What form of embryonic bone growth occurs in long bones?
Both intramembranous and intracartilaginous ossification
Explain how intacartilaginous ossification takes place?
- Hyaline cartilage becomes calcified (by calcium phosphate)
- Osteoblasts appear around the shaft of calcified cartilage and replace the cartilage with bone
- This proceeds in all directions from the diaphysis (the primary ossification centre)
- At the same time the bone collar ossifies intramembraneosly within the periosteum
- A new (secondary) ossification centre appears at the end of the bones - the epiphysis
What separates the diaphysis from the epiphysis and what does this enable
Epiphyseal seal
Allows bone growth up to adult length
What is the most newly formed bone at the end of the diaphysis called?
Metaphysis
How does diametric growth of the bone occur?
The periosteum continues to produce concentric layers of bone whilst some bone is reabsorbed in the medullary canal
How does the process of intramembranous ossification compare to intracartilaginous ossification?
Similar process but:
- proceeds more rapidly
- grows only from a primary ossification centre
What cells break up bones (including dead or damaged bone)?
Osteoclasts
From where are osteoblasts produced?
Periosteum
What type of bone is the hard outer layer
On what kind of bones is this thickest and at what point in the bone
What is the softer spongey bone called?
Cortical bone
Thickest on long weight bearing bones and thickest in the middle of such bones
Cancellous bone
What is the lattice like aspect of cancellous bone called?
What function does these have and how do they adapt to this?
Trabeculae
Provide strength with limited weight - energy absorption and stress distribution
Adapt to direction of imposed strength - remodelled along lines of stress
What is cortical bone comprised of?
System of hollow tubes called lamellae (one within another) which are in turn composed of collagen fibres running in a single direction (but diff. direction in adjacent lamellae). Series of lamellae is called an osteon.
