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The Skeletal System
All parts are connective tissue:
Bones (skeleton)
Cartilages
Ligaments
two divisions:
Axial skeleton
Appendicular
skeleton
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Functions of Skeleton and Bones
Support of the body
Protection of soft organs
Movement due to attached skeletal muscles
Storage of minerals and fats
Blood cell formation
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Bones of the Human Body
206 bones
Two basic types
Compact bone
Dense
Calcium crystals
Spongy bone
Trabeculae - “little beams”
Many open spaces
Figure 5.2b
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Gross Anatomy of a Long Bone
Epiphysis
Ends of the bone -spongy bone
Red bone marrow
Diaphysis
Shaft - compact bone
Medullary cavity
Periosteum
Figure 5.2a
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Structure of Bone
Figure 5.1
Osteon - cylinderof bone, hascentral canal withblood vessels
Osteocytes withinspaces (lacunae),connected bysmall canals(canaliculi)
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Cartilage and Ligaments
Ligaments - dense fibrous connective tissue
Collagen fibers, fibroblasts
Cartilage - collagen and elastin fibers in baseof water. Smooth and flexible substance
used to reduce friction, provide supportunder pressure at joints
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Changes in the Human Skeleton
Embryos - hyaline cartilage
Cartilage replaced by bone = ossification
done by osteoblasts - bone building cells
Secrete osteoid (proteins, fibers, enzymes)
Osteoid replaced by calcium phosphate salts
Cartilage remains in nose, ribs, joints, andepiphyseal plates, ends of bones
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Bone Development (cont.)
Figure 5.2
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Types of Bone Cells
Chondrocytes
Cartilage-forming cells
Osteocytes
Mature bone cells
Osteoblasts
Bone-forming cells
Osteoclasts
Bone-destroying cells
Break down bone matrix for remodeling andrelease of calcium
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Mature Bone Remodeling and Repair
Changes in shape, size, strength
Dependent on diet, exercise, age
Bone cells regulated by hormones
Parathyroid hormone (PTH): removescalcium from bone
Calcitonin: adds calcium to bone
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Stages in the Healing of a Bone Fracture
Figure 5.5
Fibrocartilage callus isreplaced by a bony callus
Bony callus is remodeled toform a permanent patch
Hematoma (blood-filledswelling) is formed
Break is splinted byfibrocartilage to form a callus
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The Axial Skeleton
Forms the longitudinalpart of the body
Divided into 3 parts
Skull
Vertebral column
Bony thorax
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The Skull
Two sets of bones
Cranium
Facial bones
Bones are joined bysutures
Only the mandible isattached by a freelymovable joint
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The Hyoid Bone
only bone that doesnot articulate withanother bone
Serves as moveablebase for the tongue
Figure 5.12
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Paranasal Sinuses
Functions of paranasal sinuses
Lighten the skull
Give resonance and amplification to voice
Figure 5.10
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The Fetal Skull
Fontanelles – fibrousmembranesconnecting the cranialbones
Allow the brainto grow
Convert to bonewithin 24 monthsafter birth
Figure 5.13
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The Vertebral Column
5 regions, 33 bones
Spine has a normalcurvature
Vertebrae separatedby intervertebral discs
Figure 5.7
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The Bony Thorax
Made-up of twoparts
Sternum
Ribs (12 pr)
Figure 5.19a
Forms a cage toprotect majororgans
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The Appendicular Skeleton
Limbs (appendages)
Pectoral girdle
Pelvic girdle
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Bones of the Pectoral Girdle
Figure 5.20a–b
Clavicle – collarbone
Scapula – shoulder blade
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Bones of the Upper Limb
The arm - Humerus
The forearm - Ulna
and Radius
Hand -
Carpals
Metacarpals
Phalanges
Figure 5.21a–b
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The Pelvis
Figure 5.23a
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Gender Differences of the Pelvis
Figure 5.23c
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Bones of the Lower Limbs
Femur – thigh bone
Tibia - bears weight
Fibula - helps rotationwith ankle
Tarsals - ankle
Metatarsals - foot
Phalanges - toes
Figure 5.24a–b
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Joints (Articulations)
Classified by degree ofmovement
Fibrous joint:immovable; e.g.,fontanels
Cartilagenous joint:slightly movable,cartilage connection;e.g., backbone
Synovial joint: freelymovable
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Synovial Joints - movable; all limbs
Joint capsule:synovial membrane +hyaline cartilage
Synovial membranesecretes synovial fluidas lubricant
Hyaline cartilagecushions
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Disorders, Inflammatory ConditionsAssociated with Joints
Sprains: stretched or torn ligaments
Bursitis and tendinitis: inflammations
Arthritis: inflammation of joints
Over 100 different types
The most widespread crippling disease inthe United States
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Clinical Forms of Arthritis
Osteoarthritis
Cartilage wears out, pain, inflammation
normal aging processes
Rheumatoid arthritis
autoimmune disease –attacks the joints
Symptoms begin with inflammation ofsynovial membranes
Cartilage lost, bones fused, leads todeformities