Skeleton

pectoral girdle

clavicle scapula

spongy appears porous, has less bone matrix and more space than compact bone.consists of interconnecting rods or plates of bone called trabeculae. between the trabeculae are spaces, which in life are filled with bone marrow and blood vessels.

compact- has more matrix and is denser with fewer pores than spongy bone.blood vessels enter the substance of the bone itself and the lamellae of compact bone are primarily oriented around those blood vessels.

Femur

thigh bone

bone repair

1. hematoma formation - blood released from damaged blood vessels forms a hematoma 2. callus formation - the internal callus forms between the ends of the bones and the external callus forms a collar around the break 3. callus ossification - woven spongy bone replaces the internal and external calluses 4. bone remodeling - compact bone replaces woven bone, and part of the internal callus is removed, restoring the medullary cavity

bone growth width

1. osteoblasts beneath the periosteum lay down bone (dark brown) to form ridges separated by grooves. blood vessels of the periosteum lie in the grooves 2. the groove is transformed into a tunnel when the bone built on adjacent ridges meets. the periosteum of the groove becomes the endosteum of the tunnel .3. appositional growth by osteoblasts from the endosteum results in the formation of a new concentric lamella. 4. the production of additional concentric lamellae fills in the tunnel and completes the formation of the osteon.

chondroblast - immature cells that produce cartilagematrix chondrocyte - mature cells surrounded by cartilage matri mesenchymal cells- .some mesenchymal cells become stem cells, some of which replicate and become more specialized cell types.osteochondral progenitor cells are stem cells that can become osteoblasts or chondroblasts. they are located in the inner layer of the perichondrium and in layers of connective tissue that cover bone.

1. osteocyte- mature bone cells found within lacunae of compact bone -once an osteoblast has secreted enough bone matrix to become surrounded by it the cell is then referred to as an osteocytethey retain their connections to neighboring osteocytes through their cell extensions.osteocytes retain their connections to neighboring osteocytes become relatively inactive, compared with most osteoblasts, but it is possible for them to produce the components needed to maintain the bone matrix 2. osteoblast- immatue bone, produce the organic bone matrix extensive endoplasmic reticulum and numerous ribosomesproduce collagen and proteoglycansthey release matrix vesicles 3. osteoclast- the bone cells responsible for the breakdown of bone tissue, the removal of bone matri

cartilage growth 1. interstitial growth chondrocytes in the center of the tissue divide and add more matrix in between the existing cells.

2. appostional- bone growth, increasing size or thickness of a bone due to growth beneath the periosteum, long bones increase in width and other bones increase in size or thickness chondroblasts in the perichondrium add new cartilage to the outside edge of the existing cartilage

1. iintramembranous ossification bone forms in preexisting connective tissue membranes 1. development of ossification center 2. calcification 3. formation of trabecula e4. development of periosteum

2. endochondral ossification bone forms from a preexisting cartilage model.both methods produce woven bone which is then remodeled into lamellar bone.after remodeling, bone formed by intramembranous ossification cannot be distinguished from bone formed bone . Most bones develop from a carilage model 2. The cartilage matrix is calcified and chondrocytes die 3. Osteoprogenirator cells move in and start to differentiate. 4. Blood vessles enter developing bone bringing nutrients 5. Osteoblast build an outer surface of compact bone 6. Primary ossification centers form marrow cavity 7. Cartilage starts to ossify to form skeletal bones

1. woven bone the collagen fibers are randomly oriented in many directions

2. lamellar bone is mature bone that is organized into thin, concentric sheets or layers approx. 3-1 micrometers thick called lamellae.in general, collagen fibers of one lamella lie parallel to one another, but at an angle to the collagen fibers in the adjacent lamellae.osteocytes within their lacunae are arranged in layers sandwiched between lamellae.

veterbrae cervical- protect the arteries feeding the brain while allowing rotation thoracic- articulate with ribs and provide muscle attachment sites lumbar- lock together and provide stability and limit rotation

body - disk shaped; usually the largest part with flat surfaces directed superiorly and inferiorly; forms the anterior wall of the vertebral foramen; intervertebral disks are located between the bodiesvertebral foramen - hole in each vertebra through which the spinal cord passes; adjacent vertebral foramina form the vertebral canal vertebral arch - forms the lateral and posterior walls of the vertebral foramen; possesses several processes and articular surfaces pedicle - foot of the arch with one on each side; forms the lateral walls of the vertebral foramen lamina - posterior part of the arch; forms the posterior wall of the vertebral foramen transverse process - process projecting laterally from the junction of the lamina and pedicile; a site of muscle attachment spinous process - process projecting posteriorly at the point where the two laminae join; a site of muscle attachment; strengthens the vertebral column and allows for movement articular processes - superior and inferior projections containing articular facets where vertebrae articulate with each other; strengthen the vertebral column and allow for movement intervertebral notches - form intervertebral foramina between two adjacent vertebrae through which spinal nerves exit the vertebral canal.

3 hormones parathyroid hormone, vitamin d from a precursor in the skin or from the diet, and calcitonin from C-cells in the thyroid gland.PTH is the major regulator of blood Ca2+it is secreted from the parathyroid glands.when blood Ca2+ levels are too low, stimulates an increase in the number of osteoclasts, which break down bone elevate blood Ca2+ levels.in addition, PTH stimulates osteoblasts to release enzymes that break down the layer of unmineralized organic bone matrix covering bone, thereby making the mineralized bone matrix available to osteoclasts. calcitonin is secreted from the thyroid gland when blood Ca2+ levels are too high, inhibits osteoclast activity by binding receptors on the osteoclasts.

calcuim homestasis calcium ions move into bone as osteoblasts build new bone, and they move out of bone as osteoclasts break down bone.when blood Ca2+ levels are too low, osteoclast activity increases.osteoclasts release more Ca2+ from bone into blood than osteoblasts remove from the blood to make new bone.consequently, a net movement of Ca2+ occurs from bone into blood, and blood Ca2+ levels increase. Conversely, if blood Ca2+ levels are too high, osteoclast activity decreases. Osteoclasts release fewer Ca2+ from bone into the blood than osteoblasts remove from the blood to produce new bone.As a result, a net movement of Ca2+ occurs from the blood to bone, and blood to Ca2+ levels decrease.

osteon- the structure of compact bone that consists of a central canal and all the concentric lamellae that surround it is called a haversian system the functional unit of a long bone is an osteonit is composed of concentric rings of the matrix which surround a central tunnel and contain osteocytes vessels that run parallel to the long axis of the bone are contained within the central canals. central canals are lined with endosteum and contain blood vessels, nerves, and loos connective tissue. central canal- the center of an osteo

concentric lamellae are circular layers of bone matrix that surround the central canal. circumferential lamellae the outer surfaces of compact bone are formed by the circumferential lamellaethin plates that extend around the bone.in some bones, like on the face, the layer of compact bone can be so thin that no osteons exist and the compact bone is composed of only circumferential lamellae.between osteons are interstitial lamellae, which are remnants of concentric or circumferential lamellae that were partially removed during bone remodeling

matrix 35% organic and 65% inorganic materialthe organic material consists mostly of collagen and proteoglycansthe inorganic material consists mostly of a calcium phosphate crystal called HYDROXYAPATITE Ca10(PO4)6(OH)2

contains collagen, which provides strengthproteoglycans, which make cartilage resilient by trapping water

pefortrating canal- passageways or canals that extend from the periosteum to the medullary canal run perpendicular to the length of the bone. blood vessels from the peristeum or medullary cavity enter the bone through perforating canals.nutrients in the blood vessels enter the central canals, pass into the canaliculi, and move through the cytoplasm of the osteocytes that occupy the canaliculi and lacunae to the most peripheral cells at the edge of each osteon.waste products are removed in the reverse direction lacunaue- spaces between lamellae that contain osteocyte perichondruim- connective tissue covering cartilage, double layer outer layer of dense irregular connective tissue containing fibroblasts.blood vessels and nerves penetrate the outer layer of the perichondrium but do not enter the cartilage matrix so nutrients must diffuse through the cartilage matrix to reach the chondrocytes.

diaphysis - shaft of the bone epiphysis - part of the bone that develops from a center of ossification distinct from the diaphysis periosteum - double layers connective tissue membrane covering the outer surface of bone except where articular cartilage is present endosteum - thin connective tissue membrane lining the inner cavities of a bone articular cartilage - thin layer of hyaline cartilage covering a bone where it forms a joint epiphyseal plate - area of hyaline cartilage between the diaphysis and the epiphysis medullary cavity - large cavity within the diaphysis red marrow - connective tissue in the spaces of spongy bone or in the medullary cavity; site of blood cell production yellow marrow - fat (adipose tissue) stored within the medullary cavity or in the spaces of spongy bone

hand

distal phalanx middle phalanx proximal phalanx metacarpal V

ossification osteogensis

is the formation of new bone by osteoblasts.it occurs by appositional growth on the surface of previously existing material (bone or cartilage)example:osteoblasts beneath the periosteum cover the surface of preexisting bone.elongated cell extensions from osteoblasts connect to the cell extensions of other osteoblasts through gab junctions.bone matrix produced by the osteoblasts covers the older bone surface and surrounds the osteoblast cell bodies and extensions.the result is a new layer of bone.

perforating (sharpey) fibers- collagen fibers from tendons and ligaments that penetrate the periosteum and firmly adhere the structures to the bone.

ligament- bones are attached to other bones tendon-

sternum

manubrium, body xiphoid process

facial

maxilla, zygomatic, palatine, lacrimal, nasal, inferior nasal concha, mandible, vomer bones. frontal ethmoid mandible

body - main part of the bonehead - enlarged often rounded endmargin - edge of a boneangle - bend in a bonelinea - low ridgecrest - prominent ridge

neck - constriction between head and body of bone ramus - branch off the body beyond the angle condyle - smooth rounded articular surface of bone facet - small flattened articular surface of bone spine - very high ridgeforamen - hole in the bone cornu- horn shaped processfossa- depression in bonefoeva- small pit in boneulcus- deep narrow depressiontrochanter- tuberosity on the proximal femurlabyrinth- cavity in a bone

acromion process- the highest portion of the shoulderthe bony process indicated in the figure is the acromion process

part of the zygomatic bone and zygomatic arch- temporal process part of the temporal bone and the zygomatic arch- zygomatic process sharp process that is part of the temporal bone- styloid process part of maxilla- palatine process part of palatine bone- horizontal plate part of occipital bone- occipital condyle

hyoid

provides a point of attachment for muscles of swallowing, provides a point of attachment for muscles of speech, provides a point of attachment for muscles of the tongue.*the hyoid bone provides an attachment point for some tongue muscles and for important neck muscles that elevate the larynx during speech or swallowing.

long- most bones of the upper and lower limbs are long bones. flat- relatively thin, flat shape and usually curved like some skull bones, rubs, breastbone, shoulder-blades (scapulae)

short- round or nearly cube shaped. like bones of the wrist (carpal bones) and ankle (tarsal bones )irregular- like vertebrae and facial bones, have shapes that do not readily fit into the other three categories.

bone remodel- the process of removing old bone and adding new bone is called bone remodeling

stress remodeling (the formation of additional bone, alteration in trabecular alignment to reinforce the scaffolding, or other changes).pressure in bone causes an electrical change that increases the activity of osteoblasts; therefore, applying weight (pressure) to a broken bone can speed up the healing process. Weak pulses of electric current are sometimes applied to a broken bone to speed healing.

canaliculi- the spaces occupied by the osteocyte cell extensions lacunae- the spaces without matrix but occupied by the osteocyte cell bodies.

trabeculae supporting bundles of bony fibers in cancellous (spongy) bonethe surfaces of trabeculae are covered with a single layer of cells consisting mostly of osteoblasts with a few osteoclasts trabeculae are oriented along the lines of mechanical stress within a bone. if the force on a bone is changes slightly, the trabecular pattern realigns with the new lines of stress

rib

true ribs - superior 7 ribs that articulate with the sternum and vertebral columnfalse ribs - inferior 5 pairs of ribs that do not articulate with the sternum floating ribs - rib pairs 11 and 12 that do not articulate with either the costal cartilage or sternum*there are 12 pairs of ribs, either true or false ribs.7, true, attach directly through their costal cartilages to the sternum.inferior 5 pairs, false, do not attach directly to the sternum.8th 9th and 10th ribs, vertebro chondral ribs, joined by a common cartilage to the costal cartilage of the 7th rib which is attached to the sternum.11th and 12th ribs are floating ribs because they do not attach directly to the sternum

forarm The ulna (on the medial side of the forearm) is the side with the little finger. The radium (on the lateral side of the forearm) with the thumb

ulna olecranon process, tochlear notch, coronoid process, radial notch of ulna, ulna (shaft), ulnar notch of radius, head, styloid process proximal to distal radius: head, neck, radial tuberosity, radius (shaft), styloid process

epihyseal plate (nearest epi to diaphysis) the structure found between the epiphysis and diaphysis in a child and is the site of bone growth

zone of resting cartilage- epiphyseal plate that is nearest the epiphysis and contains randomly arranged chondrocytes zone of proliferation zone of hypertrophy zone of calcification- minerals are deposited between the columns of lacunae zone of ossified bone