Chapter 5: Osseous Tissue and Skeletal Structure
Trabeculae
Parallel struts or thick, branching plates found in spongy bone; also known as spicules
Perforating canals
Passageways that extend roughly perpendicular to the bone surface, containing blood vessels
What is the function of intramembranous ossification?
Producing the bones of the skull and clavicle.
Description of central canals
Runs parallel to osteons, contains an artery, also called haversian canal, contains a vein
Lacunae
Small chambers occupied by osteocytes, sandwhiched between layers of calcified matrix
Sesamoid bone
Small round and flat, ex: patella
What does the spongy bone form?
This is the internal layer of spongy bone that surrounds the medullary (marrow).
In which classification of bones does the diploë exist?
in flat bones.
Spiral fracture
produced by twisting stresses that spread along the length of the bone.
Comminuted fracture
shatter the affected area into multiple bony fragments.
Composition of the bone: Collagen fibers
1/3 of the bone matrix = accounts for the bones tensile and strength
Composition of the bone: the matrix
2/3 calcium phosphate and hydroxyapatite crystals.
What is the periosteum around?
A connective tissue wrapping that is connected to the deep fascia .
Osteoporosis is prevalent in women after menopause. This is due to
A decrease in estrogen levels.
Osseous Tissue
A supporting connective tissue. Contains specialized cells and an extracellular matrix which consists of protein fibers and ground substances.
Diploe
This is spongy bone between two layers of compact bone
What happens second in appositional growth?
As bone matrix is being added, the result is the formation of circumferential lamellae to outer surface.
Pneumatized bones
Bones that are hallow or contain air pockets, ex: ethmoid bone
the deposition of calcium ions into the bone tissue.
Calcification
Osteoblasts
Calls that are cuboidal in shape, and which secrete the organic components of the bone matrix.
What happend to the cartilage of a fetus under 6 weeks after development?
Cartilage cells will be replaced by bone cells.
What is the percentage of cells in bone tissue?
Cells equate to about 2-3%
Osteoprogenitor cells
Cells that differentiate from mesenchyme and are found on the innermost layer of the periosteum, as well as in the endosteum lining medullary cavities.
Canaliculi
Channels that radiate through the matrix, containing fine cytoplasmic processes and ground substance.
Why is bone strong?
Collagen and hydroxyapatite crystals make the bone extremely strong.
What type of matrix does compact bone and spongy bone consist of?
Compact bone and spongy bone contain the same matrix composition but differ in 3 dimensional arrangement of osteocytes, canaliculi and lamellae.
What is another term for intramembranous ossification
Dermal ossificaiton
What can cause changes in bone because of exercise?
Due to increase in muscular development, bone changes occur because of the stress. Bigger muscles require different ridges and bumps that are larger in size.
During endochondral ossification, the lengthening of the bone shaft stops and is marked by which event(s)?
Epiphyseal cartilage production slows and osteoblast activity increases
Before 6 weeks of development, the skeleton is composed of?
Hyaline cartilage or mesenchyme.
Two types of ossification
Intramembranous ossification and endochondral ossification
osteoclasts
Large, multinucleate cells that secrete acids through lysomal exocytosis
Lamellae
Layers of calcified matrix
Which of the following provides a good example of endochondral ossification?
Limb bones
Osteocytes
Mature bone cells.
Osteocytes
Mature bones cells that maintain and monitor the protein and mineral content of the surrounding matrix
The process where cartilage is replaced by bone cells.
Ossification
Which bone cell has a high metabollic rate?
Osteoblasts contain a high metabollic rate?
Which bone cell is completely surrounded by bone matrix?
Osteocytes are surrounded by matrix
What bone cells consist of a low metabollic rate?
Osteocytes contain a low metabollic rate
The formation of bone
Osteogenesis
What happens after circumferential lamellae are brought to the surface on bone?
Osteons are formed which allow the bone to continue enlarging.
Osteon
The basic functional unit of mature bone cell
What bones are developed during intramemranous ossification?
The clavicle, mandible, flat bone of skull, flat bones of face.
What happens first in appositional growth?
The inner layer of the periosteum differentiates to form osteoblasts and adds bone matrix to the surface.
What is developed during endochondral ossification?
The limbs, vertebrae and hips.
What structure is the functional structures for compact bone?
The osteon (hacersian)
What can the realignment of teeth cause?
The shape of the tooth sockets can be altered.
What are the two major bone tissues?
The two bone tissue major components are compact bone and spongy bone.
What type of cell are osteoprogenitor cells?
These cells are a type of stem cells.
What are osteocytes primarily doing?
These cells are always removing matrix and quickly releasing minerals. Another cell called osteoblast is quickly producing matrix that is quickly binding minerals.
Where are osteoblasts found?
These cells are found on the inner and outer surface of bones.
Where are osteoprogenitor cells found?
These cells are found on the innermost layer of periosteum and inner lining of the endosteum.
What type of cells are osteoblasts?
These cells are immature bone cells.
What layer are osteocytes in-between?
These cells are in between the matrix layer called lamellae.
What is the function of osteoprogenitor cells?
These cells are involved in repair of bones after a break.
What is the function of osteoclasts?
These cells are large multinucleated cells are responsible for removing old bone.
What type of cells are osteocytes?
These cells are mature bone cells.
What is the function of osteoblasts?
These cells are responsible for the production of new bone; osteogenesis.
What kind of cells can osteoprogenitor cells produce?
These cells can produce daughter cells that differentiate into osteoblasts.
What element do osteocyte cells release?
These cells cause a release of calcium from bone to blood.
Where do osteoclasts cells originate from?
These cells come from the same stem cells that produce monocytes and neutrophils.
Where do osteocytes reside in bone connective tissue?
These cells occupy small chambers (depressions) called lacunae, that are sandwhiched between layers of calcified matrix.
What is produced by osteoblasts?
These cells secrete the organic components of the bone matrix called osteoid; which later become mineralized.
What is the job of the Osteocytes cells?
They maintain and monitor the protein and mineral conent of the surrounding matrix.
What is the consistency of spongy bone?
This bone forms an open network of struts and plates.
What does the compact bone form in the bone?
This bone forms the walls.
What is the consistency of compact bone?
This bone is relatively solid and dense.
Short bones
box like in appearance: carpal bones
Transverse fracture
break a bone shaft across its long axis
Which type of fracture occurs when an affected area is shattered into a multitude of bony fragments?
comminuted fracture
Irregular bones
complex shapes, ex: vertebra
Displaces fracture
nondisplaced fractures retain the normal alignment of the bones or fragments.
Pott's fracture
occurs at the ankle and affects both bones of the leg
Colles fracture
usally in the distal portion of a limb, typically a result of reaching out to cushion a fall
Compression fracture
vertebrae being subject to extreme stresses
