The Two Comedians, by Chris Peters

GENERAL CONSIDERATIONS ON BONES

Kaan Yücel M.D., Ph.D. 28. September 2012 Friday

1.OSTEOLOGYGk, osteon, bone, logos,

sciencebranch of medicine concerned with the development and diseases of bone tissue

270 bones

222 bones

206 bones

Skeletal system divided into two functional/anatomical parts:Axial skeletonbones of the head, neck and trunkAppendicular skeletonbones of the limbs including those forming the pectoral (shoulder) and pelvic girdles.

126 bones

80 bones

Bone one of the hardest structures of the animal body

calcification of its extracellular matrixsome elasticity

results from the organic mattergreat rigidity

results from their lamellous structures and tubes of inorganic calcium phosphate

color in a fresh state

pinkish-white externally, deep red within.

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The skeleton is composed of cartilages and bones.Cartilage

resilient, semirigid form of connective tissue forms parts of the skeleton where more flexibility is required.

CARTILAGES AND BONES

articulating of bones participating in a synovial joint capped with articular cartilage

provides smooth, low-friction, gliding surfaces for free

movement 5

The skeleton is composed of cartilages and bones.Cartilage

resilient, semirigid form of connective tissue forms parts of the skeleton where more flexibility is required.

CARTILAGES AND BONES

articulating of bones participating in a synovial joint capped with articular cartilage

provides smooth, low-friction, gliding surfaces for free

movement 6

Blood vessels do not enter cartilage avascularDiffusion

bone /cartilage in the skeleton changes as the body grows

younger a person the more cartilage bones of a newborn are soft and flexible because mostly composed of cartilage.

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The skeleton is composed of cartilages and bones.The amount and kind of extracellular fibers in the matrix depends on the type of cartilage.

Heavy weightbearing areas or areas prone to pulling forcesMore collagen fibers, less flexible cartilage.

CARTILAGES AND BONES

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Functions of cartilage

1. support soft tissues

2. provide a smooth, gliding surface for bone articulations at joints

3. enable the development and growth of long bones.

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1. Hyalinemost common, matrix w/ moderate amount of collagen fibers articular surfaces of bones2. Elasticlarge number of elastic fibers external ear3. Fibrocartilagelimited number of cells & ground substance amidst substantial amount of collagen fibers intervertebral discs

Types of cartilage

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Bones function as supportive structures for the bodyprotectors of vital organsreservoirs of calcium and phosphoruslevers on which muscles act to produce movementcontainers for blood-producing cells

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TYPES OF BONESaccording to their shape gross anatomy1) Long bones tubular humerus in the arm

3) Flat bones protective functionsflat bones of the cranium protect the brain

2) Short bonescuboidal tarsus (ankle) carpus (wrist)

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Classification of Bones 4) Irregular bones various shapes other than long, short, or flat bones of the face

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Classification of Bones 5) Sesamoid bones patella or knee capprotect the tendons from excessive wear often change the angle of the tendons as they pass to their attachments.

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Long bones develop by replacement of hyaline cartilage plate endochondral ossification

a shaft diaphysis - two ends epiphyses

Metaphysis a part of the diaphysis adjacent to the epiphyses.

Diaphysis encloses the marrow cavity.

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2 types of bones according to histological features compact bone & spongy (trabecular) bone

relative amount of solid matter # & size of the spaces they contain

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All bones have a superficial thin layer of compact bone around a central mass of spongy bone

except where the spongy bone is replaced by a medullary (marrow) cavity.

Spongy bone found @ expanded heads of long bones + fills most irregular bones.

Compact bone forms outer shell of all bones + shafts in long bones.

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Spongy (cancellous) bone consists of thin threads of bone trabeculae

The orientation of the trabeculae is modelled by the mechanical stress to which the bone is exposed

Wolff's law

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Architecture & proportion of compact and spongy bone vary according to function

Compact bone provides strength for weight bearing.

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Fig. 11. (a) Frontal section of the humerus head of a younger person (male, 32 years). The superior border of the medullary cavity is marked by the dotted line. The arrows point to the very thin lamella of compactbone in this region. (b) Frontal section of the humerus head of an aged person (female, 97 years). The superior border of the medullary cavity is marked by the dotted line. Notice that the very thin lamella of compactbone (arrows) is not supported by spongious osseous substance.

Bone Markings and Formations

Bone markings appear wherever tendons, ligaments, and fascias are attached or where arteries lie adjacent to or enter bones.

Other formations occur in relation to the passage of a tendon (often to direct the tendon or improve its leverage) or to control the type of movement occurring at a joint.

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Arises from the bony floor & overlying temporal fasciaattaches superiorly superior temporal lineinferiorly lateral & medial surfaces of the zygomatic arch

Insertion: Coronoid process of mandible & ramus of mandible

TEMPORALIS MUSCLE

Elevation and retraction of mandible

Linear elevationsLine (in Latin linea), crest (in

Latine crista)Crista galli (crest of the cock) in the anterior part of the skull

Superior temporal line Inferior temporal line in the skull

Round elevations tubercule (small eminence), protuberance (swelling)

Tubercle of a rib

External occipital protuberance rear side of the head (skull)

Sharp elevationsspine, process

Spinous process of a vertebra

Styloid process in the skull

Rounded articular areas

head, condyleHead of the mandible Condylar process

Depressionsfossae (small depression), groove (sulcus,

long narrow depressions)

Submandibular fossa

Costal groove

ForamenHole

Mental foramen

Foramen magnumin the skull

Canala foramen having length

Optic canal in the skull in the orbita where the eye is located.

Meatusa canal entering a structure

External auditory meatus

Vasculature and Innervation of Bones

Bones are richly supplied with blood vessels.

Veins accompany arteries.

Nerves accompany blood vessels supplying bones.

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ACCESSORY BONES

.Accessory (supernumerary) bones develop when additional ossification centers appear and form extra bones.

Many bones develop from several centers of ossification, and the separate parts normally fuse.

Sometimes one of these centers fails to fuse with the main bone, giving the appearance of an extra bone.

HETEROTOPIC BONES

.Bones sometimes form in soft tissues where they are not normally present (e.g., in scars).

Horse riders often develop heterotopic bones in their thighs (rider's bones), probably because of chronic muscle strain resulting in small hemorrhagic (bloody) areas that undergo calcification and eventual ossification.

CHANGES IN BONES & BONE FRACTURES

.Trauma to a bone may break it. For the fracture to heal properly, the broken ends must be brought together, approximating their normal position. reduction of a fracture.

Fractures are more common in children than in adults.

CHANGES IN BONES & BONE FRACTURES

.Immediately after a fracture, the patient suffers severe local pain and is not able to use the injured part.

Deformity may be visible if the bone fragments have been displaced relative to each other.

OSTEOPOROSIS

.Bones become brittle, lose their elasticity, and fracture easily.

Bone scanning is an imaging method used to assess normal and diminished bone mass.

decreases in the organic & inorganic components of the bone by aging

(BONE) SCINTIGRAPHY

.metabolic activity of bone and its affinity to uptake a

detectable marker image can be captured by a scan

a wide range of indications ranging from sports related injuries to detection of metastasis (spreading of cancer) to the bones.

BONE DENSITOMETRY (DEXA, DXA)

.enhanced form of x-ray technology used to measure bone loss most often used to diagnose osteoporosis

effective in tracking the effects of treatment for osteoporosis and other conditions that cause bone loss.