Bones and Joint

what’s the importance of bones?

provide the framework of the body; organized into axial and appendicular divisions

what are the importance of ligaments?

connects bone to bone; reinforces joints

what are the importance of tendons?

connects muscle to bone; transmits muscular force

what is the importance cartilage?

supportive, resilient tissue found at joints and in structures such as the nose, ribs, and external ear

what is the importance of joints?

location where two or more bones meet; allows motion while helping hold the skeleton together

what are the main functions of the skeletal systems?

protection of vital organs, support soft tissues, leverage and movement with muscles, mineral storage, triglyceride storage in yellow marrow, and blood cell formation in red marrow

where is hyaline cartilage found?

articular surfaces, costal cartilage, nasal cartilage, and respiratory cartilage

where is fibrocartilage found?

intervertebral discs and knee menisci

where is elastic cartilage found?

external ear and epiglottis

what are the shapes of bones?

long, short, flat, irregular, and sesamoid

what’s a sesamoid bone example?

patella

what are characteristics of compact bone?

dense exterior, organized into osteons, central canal carry vessels/nerves, osteocytes occupy lacunae connected by canaliculi

what are characteristics of spongy bone?

trabecular interior, organized into trabeculae containing lamellae, red or yellow bone marrow, osteocytes occupy lacunae within trabecular lamellae

where is triglyceride storage found?

yellow bone marrow

what is the metaphyses?

regions between shaft and ends; contains the growth plate

what is periosteum?

outer covering of bone

what is periosteum made of?

desne irregular connective tissue with an inner cellular layer made of osteoblasts, osteoclasts, and osteoprogenitors

what is endosteum?

cellular lining of internal bone surfaces and cavities; contains bone-remodeling cells

is bone living?

yes

what makes bone living?

blood vessels, nerves, and lymphatic vessels

what makes up 2/3 of bone’s matrix?

composite mineral

what makes up 1/3 of bone’s matrix?

collagen

what is another name for composites of mineral in bone?

hydroxyapatite minerals

what is the function of hydroxyapatite minerals?

resist compression

what is the function of collagen in bones?

resists tension and adds flexibility

what is an osteoprogenitor?

stem-like cell that produces osteoblasts

what is an osteoblast?

secretes osteoid; forms new bone

what is an osteocyte?

mature cell in a lacuna that maintains the matrix

how do osteocytes communicate?

canaliculi

what is an osteoclast?

multinucleate cell that secretes acid/enzymes to remove matrix

what does an osteoclast release during resorption?

calcium

bones remain strong when what two things are balanced?

formation and removal?

what weakens bone?

excess resorption

what is Wolffs law?

bone remolds in response to the forces placed upon it

what does heavier stress do to bone?

thicker and stronger bone

what does a trabeculae do?

reduce long bones mass without sacrificing strength by lining stress paths

what does osteogenesis mean?

bone formation

what does ossification mean?

the replacement of a precursor tissue with bone

what is calcification?

deposition of calcium salts

what happens during endochondral ossification?

1. hyaline cartilage model forms, surrounded by perichondrium

2. a bony collar forms around the diaphysis; internal cartilage calcifies and chondrocytes die

3. blood vessels invade the shaft; osteoblasts establish a primary ossification center

4. osteoclasts and osteoblasts remodel the diaphysis and form the medullary cavity

5. blood vessels enter the bone ends and establish secondary ossification center

6. epiphyses become spongy bone; articular cartilage and epiphyseal plates remain

what’s the saying for endochondral ossification?

bone chases cartilage

where does length grow?

at epiphyseal plate

where does width grow?

appositional deposition at the periosteum

what happens during intramembranous ossification?

1. mesenchymal cells cluster and become osteoblasts

2. osteoblasts produce osteoid, which mineralizes; trapped cells become osteocytes

3. woven-bone trabeculae appear, blood vessels enter, and periosteum develops

4. lamellar bone replaces woven bone; a compact outer shell forms, with marrow between internal trabeculae

what vitamins are involved in bones?

vitamin D3, C, A, K, and B12

what does vitamin D3 do in the body?

helps absorb calcium

what does vitamin C do in the body?

required to form collagen

what does vitamin A do in the body?

aids in osteoblast development

what does vitamin K do in the body?

supports mineralization

what does vitamin B12 do in the body?

supports osteoblast function and mineral density

what hormones are involved in the bones?

growth hormone & thyroid hormone, estrogen & testosterone, PTH & calcitonin, and cortisol

what do growth & thyroid hormones do in bones?

support growth, specifically during childhood

what do estrogen & testosterone do in bones?

help produce pubertal growth spurts and eventually close epiphyseal plates

what do PTH & calcitonin do in bones?

participate in blood calcium/phosphate regulation; slides emphasize PTH in adults

what does cortisol do to bones?

stress hormone can increase osteoclast activity

what happens if blood calcium is too low?

the parathyroid glands release PTH, which promotes bone resorption and activation of calcitrol which increases dietary calcium absorption

what is the order of fracture healing?

1. fracture hematoma

2. cartilage/soft callus

3. spongy bone/hard callus

4. remodels into stronger bone

how are joints classified?

function and structure

what does synarthrosis mean?

essentially no motion

what does diarthrosis mean?

freely moveable

what are the structural terms for classifying joints?

fibrous, cartilaginous, and synovial

what does fibrous mean?

fibrous connective tissue

what does cartilaginous mean?

cartilage

what does synovial mean?

capsule and joint cavity

what are sutures, gomphosis, syndesmosis, synchondrosis, symphysis, and synostosis examples of?

less-mobile joints

what does a synovial joint have?

articular cartilage, joint cavity, synovial membrane, and synovial fluid, and accessory structures

what are the six types of synovial joints?

plane, hinge, pivot, ball and socket, condylar, and saddle

where can a plane joint be found?

intervertebral process

where can a pivot joint be found?

proximal/distal radioulnar

where can a condylar joint be found?

wrist

what type of joint are the skull sutures?

fibrous and synarthrotic

what type of joint are TMJ?

synovial and hinge + plane

what type of joint are atlanto-occipital?

synovial and condylar

what type of joint are atlantoaxial?

synovial and pivot

what type of joint are between vertebral bodies?

cartilaginous and synarthrotic

what type of joint are between articular processes?

synovial and plane

what type of joint are shoulders?

ball and socket

what type of joint are sternoclavicular?

plane

what type of joint are scapulothoracic?

not actually a joint and held through rotator cuff muscles and the biceps

what type of joint are elbow?

hinge

what type of joint are proximal radioulnar?

pivot

what type of joint are wrist?

condylar

what type of joint are distal radioulnar?

pivot

what type of joint are sacroiliac?

fibrous + synovial features and plane

what type of joint are pubic symphysis?

cartilaginous symphysis

what type of joint are hips?

ball and socket

what type of joint are knees?

modified hinge

what type of joint are ankle?

hinge

what does flexion and extension mean?

decrease/increase the angle of the joint

what is abduction and adduction?

move away from/toward the midline

what is dorsiflexion and plantar flexion?

move the foot upward/point the foot downward

what is rotation?

turn a bone around the longitudinal axis

what is a pronation and supination

forearm rotation that turns the palm downward or upward

what is circumduction?

make a circle with a distal end