05/16/2023 Notes Flashcards
What is ossification (osteogenesis)?
Formation and development of bone connective tissue
What are the two methods of ossification?
Intramembranous Ossification and Endochondral Ossification
What bones are formed from intramembranous ossification?
Flat bones of the skull, zygomatic bones, maxilla, mandible, central part of clavicle, and sesamoid bones
What form of ossification forms the majority of the skeleton (upper and lower limbs, pelvis, vertebrae, and ends of clavicles)?
Endochondral Ossification
During the first 8-12 weeks of fetal development, the hyaline cartilage model is formed from what?
Chondroblasts that secrete cartilage matrix
Cartilage cells in the center of the shaft increase in size and minerals are deposited via…?
Calcification
What is the periosteal bone collar?
A thin plate of bone that surrounds the cartilage during the initial steps of calcification in the hyaline cartilage model
What is the primary ossification center
A region where bone replaces cartilage in the center of the diaphysis of the hyaline cartilage and starts bone development in both directions to the epiphyses
What are secondary ossification centers?
Similar to the primary ossification centers, but occurs in the proximal and distal epiphysis
Calcification continues until what cartilage remains in the hyaline cartilage model?
Articular cartilage and hyaline cartilage found in epiphyseal growth plates
Bone will grow in _____ as long as there is mitotic activity in the hyaline cartilage
Length
Around the ages of _____, epiphyseal growth plates will ossify and leave behind _____?
18-20; epiphyseal line
Is bone remodeling a continuous process?
Yes, it occurs throughout a person’s lifetime
What causes the growth of bone tissue in width?
Pulling on the periosteum which activates osteoblasts to secrete osteoid
How were Roman soldiers identified in the remains of Pompeii?
Their left arm bones were thickened from carrying shields
How do braces work in straightening teeth?
Activate osteoclasts and osteoblasts from the stress of tightening wires
What allows the entry of blood vessels and nerves into the bone?
Nutrient Foramen
Blood vessels that enter the bone through the nutrient foramen do what?
Bring oxygen and nutrients to the metabolically-active bone cells
What detects and signals injuries to the bone?
Nerves
What two hormones stimulate epiphyseal growth plates?
Growth hormone (somatotropin) and Sex hormones (testosterone/estrogen)
Where is somatotropin produced?
In the anterior portion of the pituitary gland
What hormones are secreted in great amounts during puberty that dramatically accelerates bone growth at epiphyseal growth plates?
Estrogen and Testosterone
What three vitamins have an effect on bone growth?
Vitamin A, C, and D
What vitamin activates osteoblasts?
Vitamin A
What does Vitamin C do to bones?
It is required for the synthesis of collagen
Vitamin D stimulates the absorption and transports what molecules?
Calcium and phosphate ions
A lack of Vitamin D in children can result in what?
Rickets
Exercise _____ bones
Strengthen
What is a concern in astronauts and bed-ridden patients?
Weakened bones that are susceptible to breaking due to lack of exercise
Moderate weight training does what to the bone?
Strengthen bones
What are the most common injuries to bones?
Fractures
What are thin breaks in the bone caused by increased physical activity in which the bone experiences repetitive loads?
Stress Fractures
What are pathological fractures?
Spontaneous fractures that occur in bones weakened by disease
What are eight examples of fractures?
Closed, open, comminuted, spiral, greenstick, depressed, displaced, non-displaced fractures
How do closed and open fractures vary?
Closed fractures do not break the skin, but open fractures break open the skin
What type of fracture is seen in bones that are splintered into multiple pieces?
Comminuted fractures
What are spiral fractures?
Bones that are broken with twisting movement that causes helical cracking
Greenstick fractures are identified by what?
Incomplete break with bowing of the bone
In a depressed fracture, portions of the bone are driven _____?
Inward
If a fracture is displaced, what does that mean?
The fragments of the bone are out of proper alignment
If fragments of the bone are in anatomical alignment, what type of fracture is it?
Non-displaced fracture
What are the four steps in healing a fracture?
Formation of a fracture hematoma, formation of a fibrocartilage callus, replacement of the fibrocartilage callus with a bony callus, bone remodeling
What do projections on bones indicate?
Sites of tendon/ligament attachment
Sites of articulations are _____?
Smooth
What bone marking indicate where blood vessels and nerves lie alongside/penetrate the bone?
Depressions, grooves, and tunnels
Condyles, facets, and heads are examples of what bone marking?
Articulating surfaces
What are examples of depressions in bone markings?
Alveolus and fossa
What are seven examples of projections in bony markings?
Crest, epicondyle, process, spine, trochanter, tubercle, tuberosity
Fissures, foramen, and sinus are examples of what bone markings?
Openings and spaces
What are the two ways that aging affects the skeletal system?
Decrease in tensile strength sue to reduced rates of protein synthesis that decreases organic compounds of bone matrix AND demineralization
Why does the skeleton become more susceptible to fractures with age?
It becomes more brittle due to the increased percentage of inorganic compounds and decreased percentage of organic compounds
What is osteopenia?
Skeleton becomes thinner and weaker as a result of losing calcium and other minerals
What do the bones of the skeleton do?
Form a framework that supports soft tissue, protects vital organs, bears the weight of the body, and aid in movement
How many bones are there in the average adult body?
Approximately 206
Why do children tend to have more bones then adults?
Their bones have not fused together yet
What are the two parts of the skeleton?
Axial skeleton and appendicular skeleton
What are the four sets of paranasal sinuses located in the nasal cavity?
Sphenoid, Maxillary, Frontal, and Ethmoidal
What function do frontal sinuses have?
Lessen the weight of the skull, moisten inhaled air, and gives resonance to the voice
Does everyone develop frontal sinuses?
No
The middle and inner ear chambers are inferior to the cranial cavity and house the organs of…?
Hearing and balance
Paranasal sinuses and ear chambers are susceptible to _____.
Infections
The sagittal suture separates what bones?
Parietal bones into left and right
What suture separates the frontal bone from the parietal bones?
Coronal suture
What suture separates the temporal bones and parietal bones?
Squamosal suture (sqaumous suture)
The lamboidal suture seperates what bones?
Parietal bones and occipital bone
What cranial bone is referred to as the “bridging bone”?
Sphenoid bone
Sphenoidal sinuses are hollow and contain many foramina, which puts it at risk of what?
Fractures by traumatic movement of the brain
What does the sella turcica hold?
The pituitary gland
Traumatic shifting may do what to the pituitary stalk?
Sever the pituitary stalk
