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The Skeletal System. Axial Skeleton Appendicular Skeleton

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  • The Skeletal System

  • Axial SkeletonAppendicular Skeleton

  • Axial Skeleton

  • Axial Skeleton

  • Axial Skeleton

  • Axial Skeleton

  • Axial Skeleton Hyoid Bone

  • Axial Skeleton

  • Axial Skeleton

  • Appendicular Skeleton

  • Appendicular Skeleton

  • Appendicular Skeleton

  • Appendicular Skeleton

  • Bone TissueOsteoblasts bone forming cellsOsteocytes The BONE CELLSOsteoclasts bone reabsorbing cells

  • Two Types of Bone TissueCompact Bone and Spongy Bone

  • Classification of BonesLong Bones Short Bones Flat BonesIrregular BonesProximalEpiphysisDiaphysisDistalEpiphysis

  • Features of Bone

    Projections that form jointsFeatures of Bone

    Projections that form joints

    Projections that are sites of muscle & ligament attachment

    Features of Bone

    Projections that form joints

    Projections that are sites of muscle & ligament attachment

    Openings that allow blood vessels and nerves to pass

    Features of Bone

    Projections that form joints

    Projections that are sites of muscle & ligament attachment

    Openings that allow blood vessels and nerves to pass


  • Structure of Bone

  • Bone Development & GrowthTwo Categories of Bone Development

    Intramembranous (Direct) forms spongy bone and eventually may form compact bone from embryonic fibrous membrane

    Endochondral - bone forms from cartilage; forms skull & flatbones

    Before week 8 of fetal life, the human skeleton is all fibrous membrane & hyaline cartilage

  • Bone Development & Growth

  • Epiphyseal Plate Growth Plate

  • Joints or Articulation

  • Joints Three Types

    Fixed Joint

    Cartilaginous Joint

    Synovial Joint

  • Synovial Joints

  • Broken Bone Repairs

  • Michael Paulus' Cartoon Skeletons

    **The adult human skeleton usually consists of 206 named bones.

    Femur (say: fee-mur) Largest bone in the body. More commonly known as the thigh bone. The femur is the longest, strongest, and heaviest bone in the body. The femur supports much of our body weight. The smallest are the ear ossicles. All 3 would find on a dime.

    The human skeleton consists of more than 200 bones of varying size, shape, and composition. In addition to their supporting function, bones, by virtue of their articulations with each other and their attachments to muscles, are responsible for the mobility of the head, trunk, and limbs. They also protect the skull, vertebral column, sensory organs, brain, and spinal cord. In their interior they accommodate the bone marrow. As a reservoir of phosphate and calcium, bone tissue plays an important role in mineral metabolism. Bone undergoes constant restructuring (remodelling) and is thereby adapted to changes in static forces. Coordination of the processes involved in the breakdown, formation, and remodelling of bone, including the deposition and removal of bone substance and the formation of new bone during the healing of fractures, is undertaken mostly by cellular messenger substances, hormones produced by the parathyroid gland, enzymes, and vitamin D. The kidneys, liver, and gastrointestinal tract influence bone tissue via their effects on protein and mineral metabolism. One factor that has an important influence on bone in both men and women is estrogen. Bones possess high compressive and tensile strength. Cortical (compact) bone consists of a layer of varying thickness that is bounded externally by periosteum and internally by a unicellular endosteal layer. Spongy (trabecular, cancellous) bone is the spongiform, porous bone that lies internal to the cortical bone and itself accommodates the bone marrow. *These bones can be grouped in two divisions: axial skeleton and appendicular skeleton. The 80 bones of the axial skeleton form the vertical axis of the body. They include the bones of the head, vertebral column, ribs and breastbone or sternum.

    The appendicular skeleton consists of 126 bones and includes what is called the free appendages and their attachements to the axial skeleton. The free appendages are the upper and lower extremities, or limbs, and their attachments which are called girdles. These 4 parts are the pectoral girdle, upper extremities, the pelvic girdle and the lower extremities. and their attachments to the axial skeleton. *Parietal (2) Temporal (2) bone where middle and inner ear embededFrontal (1) Occipital (1) Ethmoid (1) - inside orbital (eye) and nose eth moidSphenoid (1) spfee noid

    Sutures places where these bones are fused together by fibers, a little elasticisty; at birth not fused soft membranous areas between plates called fontanelle by age 2 these are ossified (hard, bone)*Maxilla (2) max cilaZygomatic (2) zy go maticMandible (1) Nasal (2) Vomer (1) inside nose, middle behind cartilageLacrimal (2) inside, btw eye & nose, next to ethnoid

    *Malleus (2) mal lee usIncus (2) Stapes (2) stay peas

    The inner and middle ear are embedded in the temporal bone*Our gift of the gab is all due to a small horseshoe-shaped bone suspended in the muscles of our neck, like a piece of fruit trapped in Jell-O. The hyoid bone, which is the only bone in the body not connected to any other, is the foundation of speech and is found only in humans and Neanderthals. Other animals have versions of the hyoid, but only the human variety is in the right position to work in unison with the larynx and tongue and make us the chatterboxes of the animal world.

    This image shows the human hyoid bone, which helps to support the tongue and serves as an attachment point for several muscles that help to elevate the larynx during swallowing and speech. The hyoid bone is unique in that it is the only bone of the body that does not articulate with any other bone. Instead, it is suspended above the larynx where it is anchored by ligaments to the styloid processes of the temporal bones of the skull.

    Hi oid*This bone is not on the list for your to memorize*Cervical vertebrae (7) Thoracic vertebrae (12) Lumbar vertebrae (5) Sacrum (1) 5 fused vertebrae say crumCoccyx (1) - 4 fused vertebrae cock sis

    *Sternum (1) Ribs (24)

    The ribs are connected to it by the costal cartilage. Without the sternum, there would be a hole in the bone structure in the middle of your chest, right above your heart and lungs. The sternum protects this vital area and completes the circle of the rib cage.

    1). True Ribs: (1-7)Superior 7 pairs of ribs attach to the sternum with costal cartilage.2). False Ribs (8-10)3 pairs of ribs lack the sternal attachment, but connect to the costal cartilage of the rib 7.3). Floating Ribs (11-12)no anterior attachment

    *Clavicle (2) collar boneScapula (2) shoulder blade scap u la

    *Humerus (2) Radius (2) Ulna (2) ul naCarpals (16) Metacarpals (10) Phalanges (28) fa lange

    *Pelvic girdle

    Coxal, innominate, or hip bones (2)

    ring of bone forming the skeleton of the pelvis, supporting the vertebral column*Femur (2) - thigh boneTibia (2) Fibula (2) Patella (2) - kneecap - front of kneeTarsals (14) connection between leg & foot tarsusMetatarsals (10) Phalanges (28) *Osteoblasts are bone-forming cells. They are connective tissue cells found at the surface of bone. They can be stimulated to proliferate and differentiate as osteocytes.Osteocytes are bone cells. Osteocytes manufacture type I collagen and other substances that make up the bone extracellular matrix. Osteocytes will be found enclosed in bone.Osteoclasts are bone-resorbing cells ("-clast" means to break; osteoclasts break down bone). They are large, multinucleate cells that form through the fusion of precursor cells. Unlike osteoblasts, which are related to fibroblasts and other connective tissue cells, osteoclasts are derived from stem cells in the bone marrow that also give rise to monocytes.

    Osteoclasts resorb bone tissueNew bone substance is produced by osteoblasts, which tend to refill resorption lacunae as they arise. The new bone material, or osteoid, formed in this way is rendered hard by deposition of calcium phosphate crystals. Once the original bone-forming cell has been incorporated into this bone matrix, it stops dividing and (now known as an osteocyte) comes to occupy a small cavity (bone lacuna) in the matrix. From this lacuna radiate slender channels containing extensions of the osteocyte. These communicate with the osteocytes of neighbouring lacunae. Osteoclasts, by contrast, break down bone matrix. These large cells, which have become multinucleate by a process of cell fusion, are derived from hemopoietic stem cells of the bone marrow. They erode bone substance by forming resorption lacunae. In the middle of such a lacuna grows a blood capillary that supplies nutrients to the bone cells. Once the lacuna acquires a certain depth, osteoblasts respond by filling it with osteoid. While some tunnels are closed with bone material, osteoclasts construct others, in the process cutting older concentric rings of osteocytes. The more osteoclasts are activated, the more bone material is resorbed. Each osteoclast leaves behind a resorption lacuna with an average size of 30 (width) x 70 (length) x 30 (depth) microns. As the number and depth of resorption lacunae increases and as the diameter of the remaining trabeculae (lamellae) decreases, the trabecular bone becomes increasingly brittle. Only 5 to 20 percent of the bone surface undergoes remodelling at any given time, the rest remaining in the quiescent phase. The local remodelling process, which begins with activation of osteoclasts and ends

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