Skeletal System Dr. Lubna Nazli 1. Objectives 2 Components Functions of bone Number of bones Bone types Bone structure Bone classification Bone ossification

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  • Skeletal System

    Dr. Lubna Nazli*

  • Objectives *Components Functions of boneNumber of bonesBone typesBone structureBone classificationBone ossificationAxial skeletonAppendicular skeletonApplied aspects

  • Skeletal System

    Composed of the bodys bones and associated ligaments, tendons, and cartilages.The human skeleton consists of 206 bones.We are actually born with more bones (about 300), but many fuse together as a child grows up.These bones support your body and allow us to move.*

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  • The longest bone in our body is the femur (thigh bone).The smallest bone is the stapes bone inside the middle ear.*

  • Functions of bone

    Bones function in:Support of soft tissuesMovementProtectionMineral homeostasis - calcium and phosphateBlood cell production - red marrow*

  • Types of Bone

    Cancellous / spongyFound in marrow cavityNo Haversian systemsSurface lined by endosteum CompactForms the dense shell of bonesHas Haversian systemsOuter surface lined by periosteumInner surface lined by endosteum

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  • Compact and Spongy Bone Tissue OrganizationBones of the skeleton contain a combination of both types of bone tissue organization.Compact bone dense outer layerSpongy bone honeycomb of trabeculaefilled with yellow bone marrow

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  • Anatomy of a Typical Long Bone*

  • Bone structure

    Dense outer layer of compact bone.Internal spongy (cancellous) boneLong bones have internal marrow cavity*

  • Bone Classification by Shape*

  • Classification of Bones:

    By ShapeLong bones longer than they are wide (e.g., humerus, femur, ulna, radius, tibia & fibula)*

  • Flat bones thin, flattened, and a bit curved (e.g.,sternum, ribs and most skull bones)*

  • Short bonesCube-shaped bones of the wrist and ankleEg: carpals & tarsal bones*

  • Sesamoid bones Bones that form within tendons. (e.g., patella)

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  • Irregular bones bones with complicated shapes (e.g: vertebrae and hip bones)*

  • Bone structure

    Typical long bone structure:articular cartilageepiphyses (ends) Spongy bonediaphysis (shaft) Compact boneMetaphysis periosteummedullary (marrow) cavityendosteum*

  • Bone is covered by a double-layered membrane known as the periosteum.It has an outer fibrous layer of dense irregular connective tissue.Inner cellular layer contains osteoprogenitor cells and osteoblasts.

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  • Periosteum is richly supplied with nerve fibers, lymphatic vessels and blood vessels.These enter the bone of the shaft via a nutrient foramen.Periosteum is connected to the bone matrix via strong strands of collagen.(SHARPEYS fibers.)

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  • Structure of short, flat and irregular bones

    outer thin plates of periosteum covered compact boneinner endosteum covered spongy bone*

  • Bone ossificationMembranous ossificationCartilaginous ossification*

  • The skeleton has two parts:the axial skeletonthe appendicular skeleton.

    The axial skeleton includesthe skull,the hyoid bone,the vertebral column (spine, sacrum, and coccyx),the sternum, and the ribs.

    Its components are aligned along the long axis ofthe body.*

  • The appendicular skeleton includesbones of the upper extremities (arms, forearms, and hands),the pectoral (shoulder) girdle,the pelvic (hip) girdle,the bones of the lower extremities (thigh, knee, leg, and foot).

    Its components are outside the body main axis.

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  • The Appendicular Skeleton

    1.Pectoral girdle2.Upper limbs3.Pelvic girdle4.Male and Female pelvis5.Lower limbs

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  • Vertebral ColumnCervicalIn neck regionThoracicPosterior to thoracic cavityLumbarSupport lower backSacrumFive fused sacral vertebraeCoccyxFour fused coccygeal vertebrae*

  • Vertebral RegionsCervicalNeck C1-C7ThoracicArticulate with ribs T1-T12LumbarLargest and strongest L1-L5SacrumTriangular bone 5 fused sacral vertebraeCoccyxSmall triangular boneUsually 4 fused coccygeal vertebrae

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  • Abnormal Curvatures

    ScoliosisAn abnormal lateral curvature of the spinal columnCurvature can occur in an S or C deviation

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  • KyphosisAn exaggerated dorsal curvature in the dorsal regionCommon is aged individuals because of osteoporosis

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  • LordosisAccentuated lumbar curvatureBeing overweight or pregnant causes an excessive load up front

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  • Interesting medical facts related to skeletal system!Estimating the age and sex of individual.In suspicious death the cause of death is known by forensic experts using bones.Bone grafts in reconstruction and repair.Bone injuries and their complications.

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  • Applied anatomyFracturesAvascular necrosisOsteoporosisInfectionsBone marrow transplantation

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  • SDLTo familiarise with terms describing the features of bones ( condyle, facet, tubercle)What is growing end of the bone? Its importance.*

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