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A P CHAPTER 6

• THE SKELETAL SYSTEM

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STRUCTURE FUNCTION

• STRUCTURE
• MADE UP OF BONE, CARTILAGE, AND FIBROUS
  CONNECTIVE TISSUE
• FUNCTIONS
• TO SERVE AS A FRAME WORK
• TO PROTECT DELICATE STRUCTURES
• CONTAINS PROTECTS RED BONE MARROW
• IMPORTANT IN THE REGULATION OF BLOOD CALCIUM
  LEVELS STORES EXCESS CALCIUM

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TYPES OF BONE TISSUE

• BONE CELLS or osteocytes regulate the amount of
  calcium that is deposited in or removed from the
  bone matrix
• MATRIX is the non -living part of the bone make
  up of calcium salts collagen

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TYPES OF BONE TISSUE

• COMPACT BONE
• fig 6-1
• hard dense
• Haversian systems present

• SPONGY BONE
• no Haversian systems
• looks like a sponge
• cavities contain red bone marrow

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Haversian Systems

• Microscopic cylinders of bone matrix with
  osteocytes in concentric rings with central
  canals that contain blood vessels
• See fig 6-1, B

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CLASSIFICATION OF BONESfig 6-1

• LONG BONES arms, legs, hands feet (not wrists
  ankles)
• shaft, middle portion called the diaphysis,
  compact bone.The hollow center called the marrow
  canal or medullary cavity contains yellow bone
  marrow

• end of the long bone is called the epiphyses. It
  is spongy bone covered with a thin layer of
  compact bone.

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CLASSIFICATION OF BONES fig 6-1

• SHORT BONES
• Wrists ankles
• FLAT BONE
• Ribs, shoulder blades, hip bones cranial bones
• IRREGULAR BONES
• Vertebrae, facial bones

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JOINT SURFACES BETWEEN BONES

• COVERED WITH ARTICULAR CARTILAGE
• COVERING THE REST OF THE BONE IS PERIOSTEUM WHICH
  ANCHORS THE TENDONS LIGAMENTS, CONTAINS BLOOD
  VESSELS OSTEOBLASTS

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HOW BONE GROWS

• Embryonic stage skeleton starts out as
  cartilage fibrous connective tissue. In the
  3rd month of gestation ossification or bone
  formation starts

• All bones except the long bones ossify from the
  center outward
• Long bones ossify from the center outward in
  the ends

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HOW BONE GROWS

• At birth the bones of the head are not completely
  ossified. Fontanels or soft spots are where the
  bones are still soft allow for compression of
  the skull during vaginal birth growth of the
  brain after birth.
• Ossification of the bones of the skull is
  complete by age 2 yrs
• Fig 6-2

• Long bone ossification In the epiphyseal discs
  at the junction between the diaphysis epiphyses
  cartilage still exists is completely replaced
  with bone by age 16-25 yrs.
• Fig 6-3

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Bone Growth Maintenance

• Heredity genetic potential determines how tall
  a person MAY become
• Nutrition need vitamins C A, calcium,
  phosphorus protein to build strong bones.
  Vitamin D needed to absorb calcium in the
  intestines.

• Hormones needed for cell division, protein
  synthesis, calcium metabolism energy production
• Exercise or stress-bones in the legs feet need
  to bear weight or they will lose calcium become
  brittle such as in osteoporosis

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DIVISIONS OF THE SKELETON

• THE AXIAL SKELETON which forms the axis of the
  body skull, vertebrae the ribcage
• THE APPENDICULAR SKELETON which supports the
  appendages or limbs bones of the arms legs,
  shoulder pelvic girdles

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THE SKULL

• Cranial bones 8 form the case for the brain,
  eyes ears
• frontal bone
• parietal bones -2
• temporal bones-2
• occipital bone
• sphenoid bone
• ethmoid bone

• Sutures
• the immovable joints between the cranial bones

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Facial Bones - 14

• mandible lower jaw
• maxillae upper jaw
• paranasal sinuses mastoid sinuses
• air cavities found in the head which make the
  skull lighter give resonance to the voice

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VERTEBRAL COLUMN

• Made up of individual bones called vertebrae
• names indicate where they are located along the
  spinal column
• 7 cervical in the neck
• 12 thoracic form joints with the ribs on the
  posterior side of the trunk

• 5 lumbar found in the small of the back
• 5 sacral fused into one sacrum
• 4-5 coccygeal fused into one coccyx or tailbone

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RIBCAGE

• Sternum or breastbone
• upper-manubrium
• central-body
• lower-xiphoid process
• True ribs 1st 7 pairs articulate with the
  sternum
• False ribs next 3 pairs articulate with the 7th
  costal cartilages
• Floating ribs last 2 pairs do not articulate
  with the sternum

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SHOULDER ARM

• SHOULDER girdle attaches the arms to the axial
  skeleton
• scapula shoulder blade
• clavicle collar bone
• ARM
• humerus upper arm bone
• radius thumb side bone of the lower arm
• ulna little finger side bone of the lower arm
• carpals wrist bones
• metacarpals hand bones
• phalanges fingers

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THE HIP

• PELVIC GIRDLE consists of the 2 hip bones
• HIP BONE
• ilium flared, upper portion
• ischium lower, posterior part we sit on
• pubis lower, most anterior part
• pubic symphysis where the 2 pubic bones meet.
  It is a piece of fibrous cartilage.
• acetabulum socket in the hip bone that
  connects to the femur

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LEG

• femur long, upper bone of the thigh
• patella kneecap
• tibia wt bearing bone of the lower leg
• fibula smaller, non wt bearing bone of the
  lower leg
• tarsals ankle bones
• metatarsals bones of the feet
• phalanges bones of the toes

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JOINTS ARTICULATIONStable 6-5, fig 6-15

• Classified by amount of movement
• synarthrosis immovable-sutures in the cranial
  bones
• amphiarthrosis slightly movable-symphysis
  joint between adjacent vertebrae
• diarthrosis freely movable-ball socket in
  the hip, pivot, hinge joints

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SYNOVIAL JOINTS

• All are diarthrotic or freely movable joints
• Made up of
• articular cartilage smooth on joint surfaces
• joint capsule provides stability is made up
  of strong fibrous connective tissue
• synovial membrane lines the joint capsule
  secretes synovial fluid
• bursae sacs of synovial fluid that permit
  tendons to slide easily across joints