Classification of Bones  Axial skeleton – bones of the skull,...

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Transcript of Classification of Bones  Axial skeleton – bones of the skull,...

Chapter 6: Skeletal System

Chapter 7: Skeletal SystemClassification of BonesAxial skeleton bones of the skull, vertebral column, & rib cageAppendicular skeleton bones of the upper and lower limbs, shoulder, & hipBones contain several tissues bone tissue, nervous tissue, cartilage, blood, epithelium around vesselsClassification of Bones: By ShapeLong bones longer than they are wide (humerus, femur, radius, ulna, tibia, fibula, fingers, & toes)Short bones cube-shaped bones of the wrist & ankleBones that form within tendons (patella)Flat bones thin, flattened, and a bit curved (sternum, scapula, ribs, & most skull bones)Irregular bones bones with complicated shapes (vertebrae & hip bones)Function of BonesSupport form the framework that supports the body and cradles soft organsProtection provide a protective case for the brain, spinal cord, and vital organsMovement provide levers for muscles

Function of BonesMineral storage reservoir for minerals, especially calcium & phosphorus release into blood with neededBlood cell formation hematopoiesis occurs within the marrow cavities in bonesRed marrow make blood cellsYellow marrow store fatBone MarkingsBulges, depressions, and holes that serve asSites of attachment for muscles, ligaments, and tendonsJoint surfacesConduits for blood vessels and nervesBone Markings: Projections-Sites of Muscle & Ligament Attachment Tuberosity rounded projection Crest narrow, prominent ridge of boneTrochanter large, blunt, irregular surfaceLine narrow ridge of boneTuberosity Crest Trochanter Line 7Bone Markings: Projections Sites of Muscle & Ligament AttachmentTubercle small rounded projectionEpicondyle raised area above a condyleSpine sharp, slender projectionProcess any bony promenenceTubercle Epicondyle Spine Process 8Bone Markings: Projections Projections That Help to Form JointsHead bony expansion carried on a narrow neckFacet smooth, nearly flat articular surfaceCondyle rounded articular projectionRamus arm-like bar of boneHead Facet Condyle Ramus 9Bone Markings: Depressions & OpeningsMeatus canal-like passagewaySinus cavity within a boneFossa shallow, basin-like depressionGroove furrowFissure narrow, slit-like openingForamen round or oval opening through a boneMeatus Sinus Fossa Groove Fissure Foramen 10Gross Anatomy of Bones: Bone TextureCompact bone dense outer layerSpongy bone honeycomb of trabecular filled with yellow bone marrowStructure of Long BoneLong bones consist of a diaphysis and an epiphysisDiaphysisTubular shaft that forms the axis of long bonesComposed of compact bone that surrounds the medullary cavityYellow bone marrow (fat) is contained in the medullary cavityStructure of Long BoneEpiphysesExpanded ends of long bonesExterior is compact bone, and the interior is spongy boneJoint surface is covered with articular (hyaline) cartilageEpiphyseal line separates the diaphysis from the epiphysesStructure of Short, Irregular, & Flat BonesThin plates of periosteum-covered compact bone on the outside with endosteum-covered spongy bone on the insideHave no diaphysis or epiphysisContain bone marrow between the traveculaeNo medullary cavityResponse to Mechanical StressWolffs law a bone grows or remodels in response to the forces or demands placed upon itObservations supporting Wolffs law include:Long bones are thickest midway along the diaphysis (where bending stress in the greatest)Curved bones are thickest where they are most likely to buckleResponse to Mechanical StressTrabeculae form along lines of stressLarge, bony projections occur where heavy, active muscles attachBone Fractures (Breaks)Bone fractures are classified by:The position of the bone ends after fractureThe completeness of the breakThe orientation of the bone to the long axisWhether or not the bone ends penetrate the skinTypes of Bone FracturesNondisplaced bone ends retain their normal position

Displaced bone ends are out of normal alignmentTypes of Bone FracturesComplete bone is broken all the way through

Incomplete bone is not broken all the way through

Linear the fracture is parallel to the long axis of the bone

Types of Bone FracturesTransverse the fracture is perpendicular to the long axis of the bone

Compound (open) bone ends penetrate the skin

Simple (closed) Bone ends do not penetrate the skinCommon Types of FracturesComminuted bone fragments into three or more pieces ( common in the elderly)

Spiral ragged break when bone is excessively twisted (common sports injury)

Depressed broken bone portion pressed inward (typical skull fracture)Common Types of FracturesCompression bone is crushed (common in porous bones)

Epiphyseal epiphysis separates from diaphysis along epiphyseal line; can hinder growth (occurs where cartilage cells are dying)

Greenstick incomplete fracture where one side of the bone breaks and the other side bends (common in children)Comminuted Fracture

Spiral Fracture

Depressed Fracture

Compression Fracture

Epiphyseal Fracture

Greenstick Fracture

Stages in the Healing of a Bone FractureHematoma formation:Torn blood vessels hemorrhage

A mass of clotted blood (hematoma) forms at the fracture site

Site becomes swollen, painful, and inflamedStages in the Healing of a Bone FractureFibrocartilaginous callus forms

Granulation tissue (soft callus) forms a few days after the fracture

Capillaries grow into the tissue and phagocytic cells begin cleaning debrisStages in the Healing of a Bone FractureThe fibrocartilaginous callus forms when:Osteoblasts and fibroblasts migrate to the fracture and begin reconstructing the bone

Fibroblasts secrete collagen fibers that connect broken bone ends

Osteoblasts begin forming spongy bone

Osteoblasts furthest from capillaries secrete an externally bulging cartilaginous matrix that later calcifiesStages in the Healing of a Bone FractureBony callus formation:New bone trabeculae appear in the fibrocartilaginous callus

Fibrocartilaginous callus coverts into a bony (hard) callus

Bone callus begins 3-4 weeks after injury & continues until firm union is formed 2-3 months laterStages in the Healing of a Bone FractureBone remodeling:Excess material on the bone shaft exterior and in the medullary canal is removed

Compact bone is laid down to reconstruct shaft wallsStages in the Healing of a Bone Fracture

JointsWeakest parts of the skeletonArticulation site where two or more bones meetFunctions of jointsGive the skeleton mobilityHold the skeleton togetherJointsA joint is a junction between bonesJoints have differences in degree of motionImmovableSlightly movableFreely movableMore commonly classified by their structure or the material that binds the joints together:Fibrous jointsCartilaginous jointsSynovial joints

Fibrous JointsLie between bones that closely contact one anotherThere is no joint cavityThin layer of dense connective tissue joins the bones at such jointsMost are immovable some can move slightlyThere are 3 types:Sutures occur between the bones of the skullSyndesmoses connection between the distal end of the tibia & fibula and radius & ulnaGomphoses peg-in-socket fibrous joint between a tooth and its alveolar socketCartilaginous JointsArticulating bones are united by cartilageLack a joint cavityTwo types:Synchondroses Bar or plate of hyaline cartilage unties the bonesImmovableEx) joint between first rib and the sternumSymphysesHyaline cartilage covers the articulating surface of the boneJoint is designed for strength and flexibilityEx) intervertebral joints & pubic symphysis of the pelvisSynovial JointsThose joints in which the articulating bones are separated by a fluid-containing joint cavityAll are freely movable diarthrosesEx) all limb joints & most joints of the bodySynovial joints all have the following:Articular cartilageJoint (synovial) cavityArticular capsuleSynovial fluidReinforcing ligamentsTypes of Synovial JointsBall-and-socket jointsConsists of a bone w/ a ball-shaped head than articulates with a cup-shaped cavity of another bone

Allows the widest range of motion that any other joint

Ex) shoulder & hipTypes of Synovial JointsCondyloid jointsOval-shaped condyle of one bone fits into an elliptical cavity of another bone

This joint allows for flexion, extension, adduction, abduction, & circumduction movements

Ex) Joints between the metacarpals and phalangesTypes of Synovial JointsGliding jointsArticulating surfaces are nearly flat or slightly curved

Allow sliding and twisting movements

Ex) Joints in the wrist, ankle, and between the articular processes of adjacent vertebraeTypes of Synovial JointsHinge jointsConvex surface of one bone fits into the concave surface of another

Resembles the hinge of a door

Ex) Elbow, knee, joints of the phalanges

Types of Synovial JointsPivot jointsCylindrical surface of one bone rotates within a ring formed of bone and ligament

Movement is limited to the rotation around a central axis

Ex) joint between the proximal ends of the radius and the ulnaTypes of Synovial JointsSaddle jointsForms between bones whose articulating surfaces have both concave and convex regions

Surface of one bone fits the complementary surface of the other

Permits a variety of movements

Ex) joint between the trapezium and the metacarpal of the thumbTypes of Joint MovementsFlexion bending parts at a joint so that the angle decreases at the jointExtension straightening parts at a joint so that the angle of the joint increasesDorsiflexion bending the foot at the ankle toward the shinPlantar flexion bending the foot at the ankle toward the soleHyperextension exce