The Skeletal System Part One

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The Skeletal SystemPart One
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Functions of Bones

• Support
• Protection
• Movement
• Storage
• Blood cell formation

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Classifications of Bones

• Compact bone
• Dense
• looks smooth
• homogeneous
• Spongy bone
• Small needlelike pieces of bone
• lots of open space

• Flat bones
• Thin
• Flattened
• Usually curved
• Long bones
• Typically longer than wide
• Mostly compact
• Shaft with heads at both ends
• All bones of limbs (except wrist and ankle) are
  long
• Irregular bones

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Projections that are sites of muscle attachment

• Tuberosity
• Large rounded projection may be roughened
• Crest
• Narrow ridge of boneusually prominent
• Trochanter
• Very large, blunt, irregularly shaped process
• Line
• narrow ridge of bone less prominent than a crest

• Tubercle
• small rounded projection or process
• Epicondyle
• raised area on or above a condyle
• Spine
• sharp, slender, often pointed projection

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Projections that help form joints

• Head
• Bony expansion carried on a narrow neck
• Facet
• smooth, nearly flat articular surface
• Condyle
• Rounded articular projection rockers
• Ramus
• Armlike bar of bone

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Depressions and openings allowing blood vessels
and nerves to pass

• 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
• Fissure
• Narrow, slitlike opening
• Foramen
• Round or oval opening through a bone

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General Bone Histology
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General Bone Histology

• Immature bone
• Fetal or repairing adult bone
• More cells, more random
• Mature bone
• Ossified bone
• Fewer cells, less random
• more matrix
• Ossification
• Requires
• Collagen - Crystallization nucleus
• Minerals- Hardness
• Also Called
• Crystalization, mineralization, Calcification

• Matrix
• Water
• Mineral salts
• Determine bone hardness
• Ca3(PO4)3 - Hydroxyapatite
• Mg(OH)2- magnesium hydroxide
• Others
• Protein fibers
• Collagen- flexibility
• tensile strength

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General Bone Histology

• Cell
• Osteoclasts
• From circulating monocytes
• Break down bone
• Secrete alkaline phosphatase
• Located on surface

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General Bone Histology

• Cell
• Osteoprogenitors
• From mesenchyme
• Not specialized
• Have mitotic potential
• Can become osteoblasts
• Locations
• Inner periosteum
• Endosteum
• Blood vessel canals

• Osteoblasts
• Build bone
• No mitosis
• Secrete matrix
• Located on surface
• Osteocytes
• Mature bone cells
• No mitotic potential
• Actually osteoblasts that are surrounded by bone
• Maintain osseous tissue

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General Bone Histology
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Structure of a Long Bone
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Microscopic Structure Of Bone

• Compact Bone
• Osteon
• Haversian Canal
• Perforating Canals
• Lamella
• Osteocytes
• Lacunae
• Canaliculi

• Spongy Bone
• Trabeculae
• Lamellae
• Osteocytes
• Canaliculi

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Microscopic Structure of Compact Bone
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Axial Skeleton
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Fontanels

• Functions
• Allows passage of the head through birth canal
• Allows growth of brain during infancy

• Locations
• Anterior- Frontal
• Posterior- Occipital
• Anterolateral -
• Sphenoidal
• Posterolateral
• Mastoid

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Fontanels
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Principal sutures of the skull

• Coronal (Frontal)
• Sagittal
• Lambdoid
• Squamous (Lateral)

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Cranial Bones

• Frontal
• Squama
• Supraorbital margin
• Supraorbital foramen (notch)
• Frontal sinus
• Frontal suture
• Orbit roof
• Parietal

• Temporal
• Temporal squama
• Zygomatic process
• Petrous portion
• Carotid foramen
• Jugular foramen
• Mandibular Fossa
• Articular Tubercle
• Mastoid process
• External acoustic meatus
• Internal acousitc meatus
• Styloid process

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Cranial Bones

• Occipital
• Foramen magnum
• Occipital condyle
• Hypoglossal Canal
• External occipital protuberance
• Superior nuchal line
• Inferior nuchal line

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The Cranial Bones
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The names in black are facial bones, those in red
are cranial bones, and those in blue are features
of the bones.
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Bones of the Skull
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Vertebrae

• Bones of vertebral column
• Common features
• Body (centrum)
• Vertebral arch
• Pedicles
• Laminae
• Processes
• Transverse - Project laterally
• Spinous - Project posteriorly
• Superior articular - Vertebra above
• Inferior articular - Vertebra below
• Facet - Articular process surface

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Vertebral Column

• Characteristics
• Composed of vertebrae
• 40 of height
• Flexible rod
• Bends
• Rotates
• Regions
• Moveable
• Cervical
• Thoracic
• Lumbar
• Immovable
• Sacral
• Coccygeal

• Separations between vertebrae
• Intervertebral foramina
• Spinal nerves
• Intervertebral discs
• Parts
• Annulus fibrosus
• Nucleus pulposus
• Functions
• Form joints
• Movement
• Shock absorber

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Vertebral Column

• Curvatures
• Normal
• Primary
• Thoracosacral - Fetal curve
• Secondary
• Cervical
• Upright head
• Lumbar
• Sitting, walking
• Abnormal
• Scoliosis - Lateral bending, thoracic
• Lordosis - Exaggerated lumbar curve
• Kyphosis - Exaggerated thoracic curve

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Cervical Vertebrae

• Small Bodies
• Large vertebral arches -
• large vertebral foramen
• Bifid spinous process, C2-C6
• Transverse process has transverse foramen

• Specialized cervical vertebrae
• Atlas C1 (Yes)
• Ring shape
• Anterior and posterior arches
• Lateral masses articulate
• No body or spinous process
• Large transverse process and foramen
• Axis C2 (No)
• Dens (odontoid process)
• Pivot point
• Hangmans fracture
• C7 vertebra prominens
• Large nonbifid spinous process
• Observed, felt at base of neck

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Cervical Vertebrae
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Vertebrae
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Thoracic Vertebrae

• Larger stronger than cervical vertebrae
• Spinous process
• Long
• Projects down
• Flattened laterally
• T1-T10 transverse process body
• Facets
• Demifacets
• Limited Movements
• Thin intervertebral discs
• Attatched Ribs

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Thoracic Vertebrae
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Lumbar Vertebrae

• Strong large bodies
• Superior articular process
• Projects medially
• Inferior articular process -
• Projects laterally
• Spinous process
• Quadrilateral
• Project posteriorly

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Lumbar Vertebrae
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Sacral Vertebrae

• 5 fused vertebra -
• Fusion starts in late adolescence
• Vertebral bodies -
• Anterior transverse lines
• Transverse processes
• sacral ala
• Posterior transverse processes
• Lateral sacral crest
• Ends of transverse processes
• Anterior sacral foramina
• Posterior sacral foramina
• Spinous processes -
• median sacral crest
• Vertebral canal continuation
• sacral canal

• Unfused S4-S5 lamina
• Sacral hiatus
• S5 inferior articular process
• Sacral cornua
• Superior anteriorly projecting border
• Sacral promontory
• Articulates with ilia
• Auricular surface
• Ligament attachments
• Sacral tuberosirty
• Anterior concavity toward pelvic cavity

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Sacral Vertebrae
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