Lecture 2.1: Cartilage and Bone

types of cartilage

hyaline, articular, elastic, fibrocartilage

functions of cartilage

support and protection, articulation surfaces, model for bone formation

interstitial growth

results in larger piece of cartilage with newest cartilage inside the existing cartilage mass

apositional growth

results in larger piece of cartilage with newest cartilage on outside edges

appositional growth of bone explanation

increases thickness (diameter) of a long bone; osteoblasts lay down external circumferential lamellae and osteoclasts enlarge medullary cavity from within bone

bone remodeling

continual production of new bone and resorption of old bone

interstitial growth of bone at epiphyseal plate stages

resting, proliferating, hypertrophic, calcification, ossification

resting stage

furthest from medullary cavity

proliferating stage

lots of mitosis

hypertropic stage

enlargement of cells

calcification stage

mineral deposition kills chondrocytes

ossification stage

capillaries from medullary cavity move in and bring osteoprogenitor cells

ossification (osteogenesis)

formation and development of bone connective tissue

examples of endochondral ossification

upper and lower limb bones, vertebrae, ribs

examples of intramembranous ossification

flat bones of skull, zygomatic, maxilla, mandible

flat bone structure

two layers of compact bone with spongy bone sandwiched between

compact bone

external surfaces of long and flat bones, solid and relatively dense, has osteons with central canals

spongy bone

internal surface of flat bones, open lattice of narrow plates called trabeculae, within flat bones - spongy bone is called dipole

functions of bone

support and protection, movement, hematopoiesis, storage of mineral (calcium & phosphate) and energy reserves (lipids)

endosteum

covers most internal surfaces of bone; contains osteoprogenitor cells, osteoblasts, and osteoclasts; active in bone remodeling, growth, fracture repair

periosteum

covers external surfaces of bones; fibrous and cellular lyers; dense irregular ct; attached by perforating (sharpey’s) fibers embedded in the bone matrix; acts as anchor for blood vessels and nerves; contains osteoprogenitor cells and osteoblasts

diaphysis of long bone

middle (shaft)

medullary (marrow) cavity

space inside of diaphysis - yellow bone marrow in adults

epiphysis long bone

end of bone (proximal and distal) - red bone marrow in adults

metaphysis

site of epiphyseal plate

articular cartilage

the type of hyaline cartilage covering epiphyseal ends

long bones

greater length than width

long bone examples

humerus, femur, ulna, tibia, metacarpals, phalanges, clavicle

short bones

length nearly equal to width

short bones examples

carpals, tarsals, patella

flat bones

flat, thin surfaces

flat bones examples

frontal, parietal, occipital, nasal, sternum, scapulae, ribs

irregular bones

complex shapes

irregular bones examples

vertebrae, ossa coxae, hyoid, temporal, ethmoid, sphenoid, maxilla, zygomatic, palatine, mandible, auditory ossicles

stress fracture

thin break due to increased activity, repetitive loads

traumatic fracture

due to excess stress to bone

pathologic fracture

occurs in bone weakened by disease

simple (closed) fracture

broken bone doesn’t penetrate the skin

compound (open) fracture

broken bone penetrates the skin

colles

fracture of the distal end of the lateral forearm bone (radius); produces a dinner fork deformity

pott

fracture is at the distal ends of the tibia and fibula

greenstick

partial fracture; one side of bone breaks, the other side is bent

comminuted

bone is splintered into several small pieces between the main parts

fracture repair proces

fracture hematoma forms, fibrocartilaginous (soft) callus forms, bony (hard) callus forms, bone is remodeled

origin

less mobile attachment

insertion

more mobile attachment

fulcrum

lever is an elongated, rigid object that rotates around a fixed point

effort arm

portion of lever between fulcrum and effort

resistance (load) arm

portion of lever between fulcrum and resistance

first class lever system

fulcrum is between effort and load; can produce advantage or disadvantage based on which is closer to the fulcrum

second-class lever system

load is between effort and fulcrum; always produces mechanical advantage; produces most force out of all lever types

third-class lever system

effort is between fulcrum and load; always produces mechanical disadvantage; most common type of lever

isometric contraction

muscle tension is less than the resistance; muscle doesn’t shorten and movement doesn’t occur

isotonic contraction

muscle tension equals or is greater than the resistance; muscle changes length and movement occurs

isotonic concentric contraction

actively shortens a muscle; most common during exercise

isotonic eccentric contraction

actively lengthen a muscle

muscle hypertrophy

increase in fast muscle fiber size; number of myofibrils per fiber increases

muscle atrophy

wasting of muscle that reduces fiber size

agonist

contraction produces the movement

antagonist

muscle whose action opposes that of an agonist

synergist

muscles that assists the agonist in performing its action

joint or articulation

place where a bone meets another bone, cartilage, or teeth

arthrology

study of joints

kinesiology

study of motion of the human body

fibrous joint

bones held together by dense connective tissue; no joint cavity

fibrous joint examples

suture, syndesmosis, gomphosis

cartilaginous joint

bones joined by cartilage; no joint cavity

cartilaginous joint examples

synchondrosis, symphysis

synovial joint

ends of bones are covered with articular cartilage; bones separated by fluid-filled joint cavity lined by a synovial membrane

synovial joint examples

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

synarthrosis

immobile joint

amphiarthrosis

slightly mobile joint

diarthrosis

freely moveable joint

sutures

joints between skull bones; synarthroses in adults and amphiarthroses in infants/children; dense regular ct adds strength

serrate sutures

distinct irregular interlocking edges between skull bones

lap sutures

hold bones together by one skull bone overlapping another

plane sutures

straight, non-overlapping edges where the skull bones meet

sutural ligament

dense regular ct between adjacent bones

types of syndesmoses

interosseous ligaments, interosseous membranes

interosseous ligaments

band of dense regular ct; amphiarthroses

interosseous ligaments examples

distal tibiofibular joint

interosseous membranes

sheet of dense regular ct; amphiarthroses

interosseous membranes examples

between parallel bones in the forearm and leg (radius and ulna, tibia and fibula)

gomphoses

joints between teeth, maxilla, and mandible; synarthroses

gomphoses examples

dentoalveolar joints

synchondroses

bones are joined by hyaline cartilage; synarthroses

synchondroses examples

epiphyseal plate, first sternocostal joint, costochondral joints

symphyses

bones are joined by a pad of fibrocartilage that resists compression/tension stresses acting as a shock absorber; amphiarthroses

symphyses examples

pubic symphysis, intervertebral joints

synovial joints

articulating bones separated by a joint cavity; diarthroses

articular (joint) capsule

outer fibrous layer made of dense regular ct; strengthens joint, inner synovial membrane that secretes lubricating synovial fluid

synovial fluid

secreted by lining cells (synoviocytes) of the membrane and chondrocytes

synovial fluid examples

hyaluronic acids and lubricin, interstitial fluid

articular cartilage

thin layer of hyaline cartilage that covers articulating surfaces; reduces friction and acts as shock absorber

joint cavity

space between articulating bones (contains small amount of synovial fluid); lubricates articular cartilages; nourishes chondrocytes of articular cartilage; absorbs shock during compression of the joint

articular discs

fibrocartilage structures, not covered in synovial membranes, can compartmentalize joint into smaller cavities, menisci (incomplete ring-like discs)

liagments

dense regular ct, sensory nerves detect pain and stretch, blood vessels nourish the joint

accessory ligaments

intracapsular ligaments, extracapsular ligaments

labra

ring-like fibrocartilage lip, helps deepen joint socket

bursae

sacs outside most synovial joints where ligaments, muscles, tendons, or bones rub; contain synovial fluid