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Chapter 5   Skeletal System

Chapter 5 Skeletal System






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    Chapter 5   Skeletal System Chapter 5 Skeletal System Presentation Transcript

    • Chapter 5 The Skeletal System
    • I. Divisions of the Skeletal System  The axial skeleton – bones of the center of the body; spine, cranium,  The appendicular – bones of the limbs and girdles  Joints, cartilages, and ligaments
    • II. Functions of Bones  Support against gravity – supports the body and anchors the organs; act as pillars to hold up the body.  Protection – cranium protects the brain; ribs protect heart and lungs; vertebral column protects the spinal chord  Movement – Muscles use bones as levers for movement  Storage – fat is stored in bones as well as minerals such as calcium and phosphorus.  Hematopoiesis – forming blood cells
    • III. Classification of Bones  206 bones in the body  Two types of bone:  Compact bones is dense and looks smooth and hard; usually the shaft of a long bone.  Spongy bone is small needle like pieces of bone and lots of open space; usually the heads of a long bone.
    • III. Classification of Bone  Classification based on Shape  Long bones – longer than they are wide; shaft with a head on both ends; femur, humerous, radius, ulna.  Short bones – cube shaped; mostly spongy; wrist and ankle bones.  Flat bones – thin and flattened; usually curved. Two layers of compact bones sandwiching a layer of spongy bone; skull, rubs, sternum
    • III. Classification of Bones  Irregular bones – “catch-all” group; any bones that do not fit with the other groups; vertebrae and the hip bone.  BEGIN STUDYING THE CHART ON PAGE 115 AND 121. YOU WILL NEED TO KNOW ALL THESE!!!
    • IV. Structure of a Long Bone  The diaphysis (shaft) makes up most of the bone’s length and is composed of compact bone.  Covering the diaphysis is the periosteum (fibrous connective tissue)  Sharpey’s fibers secure the periosteum to the diaphysis.
    • IV. Structure of a Long Bone  At each end of the long bones is the epiphysis.  Each epiphysis consists of a thin layer of compact bone enclosing an area filled with spongy bone.  Articular cartilage, instead of periosteum, covers its external surface.  Articular cartilage is smooth glassy hyaline cartilage; reduces friction at joints.
    • IV. Structure of a long bone  Thin line of bony tissue spanning the epiphysis that looks a bit different from the rest of the bone. Its called the epiphysial line.  In young bones there is an epiphyseal plate made of cartilage that allows the bone to grow.
    • IV. Structure of a long bone  The shaft is a storage area for adipose tissue (fat). This is called yellow marrow cavity or the medullary cavity.  In infants this area makes blood cells and red marrow is found there.  KNOW THE CHART ON PAGE 115.
    • V. Bone Markings  There are two categories of bone marking  Projectionsor Processes – grow out from the bony surface  Depressions or cavities – indentations in the bone.
    • V. Bone Markings  Tuberosity – large rounded projectsion; make be roughened  Crest – Marrow ridge of bone; usually prominent  Trochanter – Very large blunt, irregularly shaped process (only on the femur)
    • V. Bone Markings  Line – Narrow ridge of bone; less prominent than a crest  Tubercle – small rounded projection or process.  Epicondyle – raised area above a condyle  Spine – Sharp, slender, often pointed projection
    • V. Bone Markings  Head – Boney expansion carried on a narrow neck.  Facet – Smoth nearly flat articular surface  Condyle – Rounded articular projection  Ramus – Armlike Bar of a bone
    • V. Bone Markings  Meatus – Canal-like passageway  Sinus – Cavity within a bone, filled with air and lined with mucous membrane  Fossa (shallow, basinlike depression in a bone, often serving as an articular surface.  Groove - Furrow
    • V. Bone Markings  Fissure – Narrow, slit like opening  Foramin/Foramina – Round or oval opening through a bone
    • VI. Microscopic Anatomy  Mature bone cells are called osteocytes.  Osteocytes are found in tiny cavities withing the matrix called lacunae.  The lacunae are arranged in circles called lamellae around a central Haversian canal.  These together make up an osteon.
    • VI. Microscopic Anatomy  Canaliculi are tiny canals that radiate outward from the central canals to all the lacunae  Bone is well vascularized and heals well.  Volkmann’s canals run at right angles to the shaft.
    • VI. Microscopic Anatomy  Calcium salts make the bone hard.  The organic parts (especially the collagen fibers) provide flexibility and great strength
    • VII. Bone Formation, Growth, and Remodeling  In an embryonic bone - mostly hyaline cartilage.  The bones in a fetus are about 60% bone/40% hyaline cartilage.  In a child, the Epiphyseal plate is still cartilage.  In adults, Epiphyseal plate is replace with bone leaving only the epiphyseal line.
    • VII. Bone Formation, Growth, and Remodeling  Ossification – bone formation  Osteoclasts – bone destroying cells to release calcium into the blood  Rickets – disease in children in which the bones fail to calcify – lack of calcium in the diet or vitamin D – Legs bow under the weight of the body.
    • VIII. Bone Fractures  As you age, bones thin and weaken. Fractures are more common.  Fractures are treated by reduction  Closed reduction – bones are coaxed back into their normal positions by the doctor.  Open reductions – surgery is performed and the bone ends are secured together with pins or wires.
    • VIII. Bone Fractures  Bones must be immobilized with a cast.  Healing time for simple bones is 6 to 8 months, but is longer for large bones and in elderly people.
    • VIII. Bone Fractures  4 events of bone fractures  A hematoma is formed. Blood vessels are ruptured and blood clots.  Fibrocartilage callus formation – slints the gap between the bones. Capillaries reform.  Bony callus formation – Fibrocartilage is replaced by bony callus  Bone remodeling – patch the bone permanently.
    • IX. Bone Fractures  Simple fracture – Bone breaks cleanly, but doesn’t penetrate the skin.  Compound fracture – Bone protrudes through the skin  Comminuted fracture – bone breaks into many pieces.  Compression – Bone is crushed  Depressed – Beon is pressed inward.
    • IX. Bone Fractures  Impacted Fracture – Broken bone ends are forced into each other  Spiral Fracture – Ragged break occurring when excessive twisting forces are applied to a bone.  Greenstick – Bone breaks incompletely much in the way a green twig breaks.
    • XIII. The Vertebral Column  Formed of 26 irregular bones  Protects and supports the spinal cord  The sacrum is 5 fused vertebrae  The coccyx is 4 fused vertebrae (tail bone)  Between individual vertebrae are intervertebral discs made of flexible fibrocartilage which cushion the vertebrae and absorb shock.
    • XIII. The Vertebral Column  Young discs have more water content and are more flexible.  Body or centrum – main part of the vertebra  Vertebral arch – formed from the joining of posterior extentions; the laminae and pedicles make up the vertebral arch
    • XIII. The Vertebral Column  Vertebral foramen – canal through which the spinal cord passes.  Transverse process – two lateral projections from the bertebral arch  Spinous process – single projection arising from the posterior aspect of the vertebral arch  Superior and inferior articular processes - paired projections lateral to the vertebral foramen, allowing a vertebra to form joins with adjacent vertebrae
    • XIII. The Vertebral Column  The spine is divided into section:  Cervical vertebrae – first 7 vertebrae of the spine. – First cervical vertebrae is called the atlas. The atlas has no body and articulates with the occipital condyles of the skull – Second cervical vertebrae is called the axis. The axis acts as a pivot for rotation of the atlas (and skull). The axis has a large process called the odontoid process or dens. – These are numbered C1, C2, C3, etc
    • XIII. The Vertebral Column  Thoracic vertebrae include 12 individual vertebrae.  They are number T1, T2, T3, etc.  The body of the vertebrae is somewhat heartshaped  The two demifacets on each side receive the ribs.  The spinous process is long hooks sharply downward.
    • XIII. The Vertebral Column  The Lumbar Vertebrae  5 Block-like vertebrae  Hatchet shaped spinous process  These are the sturdiest of the vertebrae  Labeled L1, L2, L3, etc.
    • XIII. The Vertebral Column  Sacrum  Fused 5 vertebrae  The wing-like alae articulates with the hip  Forms the posterior wall of the pelvis  The midline of the sacrum is roughened by the median sacral crest which is made from fused spinous processes.
    • XIII. The Vertebral Column  Coccyx  Remant of the tailbone that other vertebrates have.  3 to 5 fused vertebrae
    • XIV. Bony Thorax or Thoracic cage