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Kaan Yücel M.D., Ph.D. 03. February. 2014 Monday

INTRODUCTION TO OSTEOLOGYBONES

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Osteology (Gk, osteon, bone, logos, science) branch of medicine concerned with the development

and diseases of bone tissueThe human skeleton

206 bones in adults

1.INTRODUCTION TO OSTEOLOGY

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The skeletal system may be divided into 2 functional parts:The axial skeleton • head (cranium or skull)• neck (hyoid bone and cervical vertebrae) • trunk (ribs, sternum, vertebrae, and sacrum)The appendicular skeleton • Limbs including those forming the shoulder & pelvic girdles

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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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HISTOLOGY OF THE BONEsparse cells surrounded by an extracellular network/matrix

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Osteoblasts 

secrete proteins into the matrix.

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Mature bone is composed of proteins and minerals.

60% the weight of the bone mineral

Rest - water & matrix.

90% of the matrix proteins collagen 1/3 of the bone weightvery strong forms bone, cartilage, skin, and tendons.

High resolution image of cortical bone and single collagen fibril (inset)

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Minerals of the matrix

Mainly calcium phosphate & calcium carbonate

Embedded in the protein network

Provide hardness and compressive strength.

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Matrix maintained by osteocytes 

 Haversian systems or osteons

concentric rings of osteocytes arranged around a central blood vessel.

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Principal types of bone cells

1. Osteogenic cells2. Osteoblasts3. Osteocytes4. Osteoclasts

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Periosteummembrane surrounding the bone tissue

provides a route for the vasculature and nerve supply. participates in bone growth and repair.

Endosteumlines the marrow cavity

active during bone growth, repair, and remodelingcovers trabeculae of spongy bone lines the inner surfaces of the central canals

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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

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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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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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Bone Markings and Formations

Surfaces of the bones are not smooth.

Bones display elevations, depressions and holes.

The surface features on the bones are given names to distinguish and define them.

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Vasculature and Innervation of Bones 

Bones are richly supplied with blood vessels.

Veins accompany arteries.

Nerves accompany blood vessels supplying bones.