Chp 6

articular cartilage

thing layer of cartilage covering an epiphysis, reduces friction and acts as a shock absorber

Appendicular Skeleton

126 bones that form the upper and lower limbs, as well as the shoulder and pelvic girdles that attach them to the central axis of the body

Appositional cartilage growth

new cartilage growth at the outer edge of cartilage, expanding outward, adding new layers to surface

articulation

where two bone surface meet

Axial skeleton

consists fo 80 bones that form the central core and vertical axis of the body

bone

hard, dense connective tissue that forms the structural elements of the skeleton

bone lining cells

flat cells on bone surface that help osteocytes maintain matrix

External surface: Periosteal cells

Internal: Endosteal cells

Bone markings

sites of muscle, ligaments and tendon attachment on external surfaces

Three types (projection, depression, opening)

Calcification Zone

(Epiphyseal plate 5 zones)

at the epiphysis-diaphysis junction, the cartilage matrix calcifies and the chondrocytes die and deteriorate

canaliculi (singular = canaliculus)

hair line canals that connect lacunae to each other and to central canal. Allows communication and nutrients moving.

channels within the bone matrix that house one of any osteocytes many cytoplasmic extensions that it uses to communicate and receive nutrients

cartilage

semi-rigid connected tissue found in the skeleton in areas where flexibility and smooth surface support movement

Blood supply comes from pericondrium surrounding cartilage

Made up of chondrocytes

central canal

runs through core of osteon

longitudinal channel in the center of each osteon, contains blood vessels, nerves, and lymphatic vessels also known as the haversian cancal

closed reduction

manual manipulation of a broken bone to set it into its natural position without surgery

Comminuted fracture

when a bone is crushed into three or more pieces

compact bone

dense osseous tissue that can withstand compressive forces

Structural unit - osteon (haversion system) each osteon consists of concentric lamellae enclosing a central canal through which blood vessels passed

diaphysis

tubular shaft that runs between the proximal and distal ends of a long bone

diploë

layer of spongy bone, that is sandwiched between the two layers of compact bone found in flat bones

endochondral ossifciation

process in which bone forms by replacing hyaline cartilage

bones are called cartilage bones (endochondral) bones at this point, form most of skeleton

endosteum

delicate memnranous lining o a bones medullary cavity

epiphyseal plate

(growth plate) sheet of hyalin cartilage in the metaphysis of a immature bone; replaced by bone tissue as the organ grows in length

epiphysis

wide section at each end of a long bone; filled with spongy bone and red marrow

external callus

collar of hyaline cartilage and bone that forms around the outside of a fracture

flat bone

thin and curved bone; serves as a point of attachment for muscles and protects internal organs

Consists of thin plates of spongy bone inside and covered by compact bone on the outside. Bone marrow scattered throughout, no bone marrow cavity.

Cranial bones, scapulae, sternum, ribs

fracture hematoma

blood clot that forms at the site of a broken bone

Fracture: nondisplaced vs displaced

Nondisplaced: ends retain normal position

Displaced: ends of of normal alignment

Fracture: Complete vs Incomplete

Complete: broken all the way through. Incomplete: not borken all the way through

Fracture: Open vs Closed

Open/Compound: skin penetrated

Closed/Simple: skin not penetrated

Greenstick fracture

partial breaks in a bone that occur as a result of bending

hematopoiesis

production of blood cells, which occurs in the red marrow of the bones

hole

opening or depression in a bone

hypercalcemia

condition characterized by abnormally high levels of calcium

hypertophic zone

(Epiphyseal plate 5 zones)

chondrocytes enlarge and the lacunae erode

Impacted fracture

one end of a broken bone is driven into the other end

Inorganic components

hydroxyapatites (mineral salts)

65% of bone by mass, responsible for hardness and resistance to compression

Half as strong as steel by resisting compression

Strong as steel by resisting tension

Lasts long after death because of mineral composition

interna callus

fibrocartilaginous matrix, in the endosteal region, between the two ends of a broken bone

intramembranous ossification

proccess by which bone forms directly from fibrous membrane, bones are called membrane bones at this point

interstitial cartilage growth

growth of cartilage from inside, existing chondrocytes indie the tissue divide and push matrix apart to expand internally

irregular bone

bone of a complex shape; protects internal organs from compressive forces

Consists of thin plates of spongy bone inside and covered by compact bone on the outside. Bone marrow scattered throughout, no bone marrie cavity.

Vertebrae & pelvic bones

lacunae (singular = lacuna)

spaces in a bone that house osteocyte

Lamellae

Interstitial - between osteons (fill gaps between them)

Circumferential - extend around entire circumference of bone

long bone

cylinder shaped bone that is longer that it is wide; functions as a lever

• Upper limbs: Humerus (upper arm), radius and ulna (forearm), metacarpals (palm), and phalanges (fingers).

• Lower limbs: Femur (thigh), tibia and fibula (leg), metatarsals (foot), and phalanges (toes).

• Other areas: Clavicle (collarbone).

Shaft = diaphysis

Bone end = Epiphyses

Outerlayer of compact bone surrounding the spongy bone

medullary cavity

hollow region of the diaphysis; filled with yellow marrow

modeling

process during bone growth, by which bone is resorbed on one surface of a bone and deposited on another

Resorbed - break down old bone and Deposited - lay down new bone matrix

Nutrient foramen

small opening in the middle of the external surface of the diaphysis, through which an artery enters the bone to provide nourishment

Organic Components

 Osteoid (made mostly of collagen fibers, glycoproteins, and proteoglycans)

open reduction

surgical exposure of a bone to resent a fracture (surgical wires or pins placed)

orthopedist

doctor of musculoskeletal includes bones, joints, ligaments, tendons, muscles and nerves

osseous tissue

bone tissue; a hard dense connective tissue that forms the structural elements of the skeleton

ossification (also osteogensis)

bone formation

ossification center

cluster of osteoblasts found in the early stages of intramembranous ossification

Ossification Zone

(Epiphyseal plate 5 zones)

osteoclasts dissolve the calcified cartilage and osteoblasts lay down bone matrix in place of the cartilage

osteoblasts

cell responsible for forming new bone (actively mitotic)

secretes osteoids

osteoclast

cell responsible for resorbing bone

osteocyte

primary cell in mature bone; responsible for maintaining the matrix

No longer divide, respond to stimuli

osteogenic cell (osteoprogenitor cells)

Mitotically active stem cell; the only bone cells that divide; they differentiate and develope into osteoblasts

osteoid

uncalcified bone matrix secreteted by osteoblasts

Osteomalacia & Rickets

bone is inadequately mineralized

results in soft week bones, pain upon bearing weight

Osteomalacia of children is rickets: Vit D deficiency insufficient dietary calcium. bone ends are enlarged and abnormally long

osteon (also, haversian system)

basic structural unit of a compact bone; made of concentric layers of calcified matrix

consist of and elongated cylinder that runs parallel to long axis of bone. Osteon cylinder consists of several rings of bone matrix called lamellae

osteoporosis

disease characterized by a decrease in bone mass; occurs when the rate of bone resorption exceeds the rate of bone formation, common occurrence as the body ages

osteoclasts constantly remove old bone whole osteoblasts generate new bone

Osteoporotic bone (bone pain, tenderness, weakend and brittle bones)

Pagets Disease

excessive and haphazard bone deposit and resorption cause bone to grow fast and develop poorly

very high ratio of spongy to compact bone and reduced mineralization

Cause unknown, Moth-Eaten appearance

perforating canal (Volkmann’s canal)

channel that branches off from the central canal and houses vessels and nerves that extend to the periosteum and endosteum

perichondrium

memnbrane that covers cartilage

periosteum

fibrous membrane covering the outer surface of bone and continuous with ligaments

primary ossification center

region, deep in the periosteal collar, where bone development starts during endochondral ossification

projection

bone markings where part of the surface sticks out above the rest of the surface, where tendons and ligaments attach

proliferative zone

(Epiphyseal plate 5 zones)

chondrocytes divide via mitosis, lengthening the bone

Area of cartilage on diaphysis side of epiphyseal plate that is rapidly dividing

New cells moving upward pushing ephysis away from diaphysis causing lengthening of bone

region of the epiphyseal plate what makes new chondrocytes to replace those that die at the diaphyseal end of the plate and contributes to a longitudinal growth of the epiphyseal plate

red marrow

connective tissue on the interior cavity of a bone where hematopoiesis (produce new blood cells) takes place

remodeling

process by which osteoclasts resorb (bone resorption) old or damaged bone at the same time as and on the same surface where osteoblasts form new bone to replace that which is resorbed

reserve/resting/quiescent zone

(Epiphyseal plate 5 zones)

resting zone

area of cartilage on epiphyseal side of epiphyseal plate that is relatively inactive

region of the epiphyseal plate that anchors the plate to the osseous tissue of the epiphysis

secondary ossificatoin center

region of the bone development in the epiphyses

sesamoid bone

small, round bone embedded in a tendon; protects the tendon from compressive forces

patella

short bone

cube-shaped bone that is approximately equal in length, width, and thickness; provides limited motion

Areas that need strength, support and stability

• Wrist (Carpals): Bones like the scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium.

  • Ankle (Tarsals): Bones like the calcaneus (heel), talus, navicular, cuboid, and cuneiforms

Consists of thin plates of spongy bone inside and covered by compact bone on the outside. Bone marrow scattered throughout, no bone marrie cavity.

skeletal system

organ system composed of bones and cartilage that provides for movement, support and protection

spongy bone (cancellous bone)

trabeculated osseous tissue that supports shifts in weight distribution

made up of honeycomb of small needle like pieces

trabecular confer strength

trabeculae (singular = trabecula)

spikes or secretions of the lattice-like matrix in spongy bone

strength to bone (like cables to bridge)

yellow marrow

connective tissue in the interior cavity of a bone where fat is stored

zone of calcified matrix

region of the epiphyseal plate closest to the diaphyseal end; functions to connect the epiphyseal plate to the diaphysis

zone of maturation and hypertophy

region of the epiphyseal plate where chondrocytes from the proliferative zone grow and mature and contribute to the longitudinal growth of the epiphyseal plate

5 types of bones

long, short, flat, irregular, sesamoid

4 Major Stages of Bone Repair

Hematoma formation - torn blood vessels hemorrhage causing hematoma

Fibrocartilaginous callus formation  - capillaries grow into hematoma, phagocytic cells clear the debris of the fracture hematoma and dead bone cells. Next the fibroblasts secrete collagen fibers that connect broken bone ends. Then osteogenic cells differentiate into chondroblasts and osteoblasts to rebuild tissue. Chondroblasts produce the cartilage matrix that combines with the collagen fibers, this forms the fibrocartilaginous callus that fills the fracture gap

Bony callus formation - within one week, new trabeculae appear in fibrocartilaginous callus. Callus is converted to bony callus of spongy bone

Bone remodeling - begins during bony callus formation and continues for several months. Excess material on diaphysis exterior and within medullary cavity is removed, compact bone is laid down to reconstruct shaft walls, final structure resembles original structure 

Flat bone formation

Long bone formation & growth