06 Skeleton: Axial Human Biology. Classification of Bones Human body consists in 206 bones. They are...

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Transcript of 06 Skeleton: Axial Human Biology. Classification of Bones Human body consists in 206 bones. They are...

  • 06 Skeleton: AxialHuman Biology

  • Classification of BonesHuman body consists in 206 bones. They are divided in two groups:Axial skeleton (form the long axis of the body) includes bones of the skull, vertebral column, and rib cage. Functions: protecting, supporting or carry other body parts.Appendicular skeleton bones of the upper and lower limbs, shoulder, and hip. Function: locomotion and manipulation of our environment

  • Gross Anatomy of Bones: Bone TexturesEvery bone has two textures:Compact bone (also called cancellous bone) dense outer layerSpongy bone - (internal) honeycomb of trabeculae filled with red or yellow bone marrow

  • Classification of Bones: By ShapeLong bones longer than they are wide (e.g., humerus)Has a shaft plus two endsFigure 6.2aBones come in many sizes and shapes. For most part , bones are classified by their shape as: long, short, flat and irregularEx: All limb bones except patella and wrist and ankle bones are long bone

  • Structure of Long BoneFigure 6.3

  • Structure of Long BoneLong bones consist of a diaphysis and an epiphysis and membranes.DiaphysisTubular shaft that forms the axis of long bonesComposed of compact bone that surrounds the medullary cavityYellow bone marrow (fat) is contained in the medullary cavity

  • Structure of Long BoneEpiphysesExpanded ends of long bonesExterior is compact bone, and the interior is spongy boneJoint surface is covered with articular (hyaline) cartilageEpiphyseal line (remnant of the epiphyseal plate) separates the diaphysis from the epiphyses

  • Classification of Bones: By ShapeFigure 6.2bShort bonesCube-shaped bones of the wrist and ankleSesamoid bones shaped like a sesame seed that form within tendons (e.g., patella). They vary in size and number in different individual. Some sesamoid bones act to alter the direction of pull of a tendon

  • Classification of Bones: By ShapeFlat bones thin, flattened, and a bit curved (e.g., sternum, and most skull bones)Figure 6.2c

  • Structure of a Flat BoneFigure 6.4

  • Classification of Bones: By ShapeIrregular bones bones with complicated shapes (e.g., vertebrae and hip bones)Figure 6.2d

  • Function of BonesSupport form the framework that supports the body and cradles soft organs. Ex: Lower limbProtection provide a protective case for: the brain (bones of skull), spinal cord (vertebrae), and vital organs (rib cage)Movement provide levers for musclesMineral storage bone is a reservoir for minerals, especially calcium and phosphorusBlood cell formation hematopoiesis occurs within the marrow cavities of bones

  • Tuberosity rounded projectionCrest narrow, prominent ridge of boneTrochanter large, blunt, irregular surfaceLine narrow ridge of boneBone Markings: Projections Sites of Muscle and Ligament Attachment

  • Tubercle small rounded projectionEpicondyle raised area above a condyleSpine sharp, slender projectionProcess any bony prominenceBone Markings: Projections Sites of Muscle and Ligament Attachment

  • Chemical Composition of Bone: OrganicBone has both organic and inorganic components. Organic components:1.-Cells:Osteoblasts bone-forming cellsOsteocytes mature bone cellsOsteoclasts large cells that resorb or break down bone matrix2.- Osteoid unmineralized bone matrix composed of proteoglycans, glycoproteins, and collagen

  • Chemical Composition of Bone: InorganicThe balance of the bone tissue (65% by mass) consists of inorganic mineral salts:Hydroxyapatites, or mineral saltsMainly calcium phosphatesResponsible for bone hardness and its resistance to compression

  • The SkeletonThe skeleton (dried up body or mummy)It is strong, yet light, and almost perfectly adapted for the protective, locomotor and manipulative functions it performComposed of bones, cartilages, joints and ligaments, accounts for about 20% of body mass.The skeleton is divided into Axial and Appendicular

  • The Axial SkeletonThis part of skeleton supports the head, neck and trunk and it protects the brain, spinal cord and the organs in the thoraxEighty bones segregated into three regions1.- Skull2.- Vertebral column3.- Bony thorax

  • The SkullThe skull, the bodys most complex bony structure, is formed by the cranium and facial bones Cranium protects the brain and is the site of attachment for head and neck musclesFacial bonesSupply the framework of the face, the sense organs, and the teethProvide openings for the passage of air and foodAnchor the facial muscles of expression

  • Anatomy of the CraniumThe cranium can be divided in : 1.- cranial vault (calvaria) 2.- cranial base (floor)Eight cranial bones two parietal, two temporal, frontal, occipital, sphenoid, and ethmoidCranial bones are thin and remarkably strong for their weight

  • Frontal BoneForms the anterior portion of the craniumArticulates posteriorly with the parietal bones via the coronal sutureThe most anterior part of the frontal bone is the vertical frontal squama, commonly called the foreheadMajor markings include the supraorbital margins, the anterior cranial fossa, and the frontal sinuses (internal and lateral to the glabella)

  • Skull: Anterior ViewFigure 7.2a

  • Skull: Posterior ViewFigure 7.2b

  • Parietal Bones and Major Associated SuturesThey are curved, rectangular bones. Form most of the superior and lateral aspects of the skullFigure 7.3a

  • Occipital Bone and Its Major MarkingsIt articulates anteriorly with the paired parietal and temporal bones via the lambdoid and occipitomastoid sutures.It also joins with the sphenoid bone in the cranial floor via a plate called the pharingeal tubercule.Forms most of skulls posterior wall and baseMajor markings include the posterior cranial fossa, foramen magnum, occipital condyles, and the hypoglossal canalFigure 7.2b

  • Temporal BonesFigure 7.5 Between the styloid and mastoid processes exist the stylomastoid foramen that allow cranial nerve VII to leave the skull. The mastoid region of the temporal bone exhibits the conspicuous mastoid process, an anchoring site for some neck muscles

  • Sphenoid BoneFigure 7.6a, b

  • Ethmoid BoneFigure 7.7Allow the olfatory nerves to pass from the smell receptors in the nasal cavites to the brain

  • Mandible and Its MarkingsFigure 7.8a

  • Maxillary BoneFigure 7.8bThe anterior nasal spine allows the infraorbital nerve and artery to reach the face

  • Vertebral Column & Ribs

  • Vertebral ColumnFormed from 26 irregular bones (vertebrae) connected in such a way that a flexible curved structure resultsCervical vertebrae 7 bones of the neckThoracic vertebrae 12 bones of the torsoLumbar vertebrae 5 bones of the lower backSacrum bone inferior to the lumbar vertebrae that articulates with the hip bones

  • Vertebral ColumnFigure 7.13

  • Vertebral Column: CurvaturesPosteriorly concave curvatures cervical and lumbarPosteriorly convex curvatures thoracic and sacralAbnormal spine curvatures include scoliosis (abnormal lateral curve), kyphosis (hunchback), and lordosis (swayback)

  • Vertebral Column: LigamentsAnterior and posterior longitudinal ligaments continuous bands down the front and back of the spine from the neck to the sacrumShort ligaments connect adjoining vertebrae together

  • Vertebral Column: LigamentsFigure 7.14a

  • Vertebral Column: Intervertebral DiscsCushionlike pad composed of two partsNucleus pulposus inner gelatinous nucleus that gives the disc its elasticity and compressibilityAnnulus fibrosus surrounds the nucleus pulposus with a collar composed of collagen and fibrocartilage

  • Vertebral Column: Intervertebral DiscsFigure 7.14b

  • General Structure of VertebraeBody or centrum disc-shaped, weight-bearing regionVertebral arch composed of pedicles and laminae that, along with the centrum, enclose the vertebral foramenVertebral foramina make up the vertebral canal through which the spinal cord passes

  • General Structure of VertebraeSpinous processes project posteriorly, and transverse processes project laterallySuperior and inferior articular processes protrude superiorly and inferiorly from the pedicle-lamina junctionsIntervertebral foramina lateral openings formed from notched areas on the superior and inferior borders of adjacent pedicles

  • General Structure of VertebraeFigure 7.15

  • Cervical VertebraeSeven vertebrae (C1-C7) are the smallest, lightest vertebraeC3-C7 are distinguished with an oval body, short spinous processes, and large, triangular vertebral foraminaEach transverse process contains a transverse foramen

  • Cervical VertebraeTable 7.2

  • Cervical Vertebrae: The Atlas (C1)The atlas has no body and no spinous processIt consists of anterior and posterior arches, and two lateral massesThe superior surfaces of lateral masses articulate with the occipital condyles

  • Cervical Vertebrae: The Atlas (C1)Figure 7.16a, b

  • Cervical Vertebrae: The Axis (C2)The axis has a body, spine, and vertebral arches as do other cervical vertebraeUnique to the axis is the dens, or odontoid process, which projects superiorly from the body and is cradled in the anterior arch of the atlasThe dens is a pivot for the rotation of the atlas

  • Cervical Vertebrae: The Axis (C2)Figure 7.16c

  • Cervical Vertebrae: The Atlas (C2)Figure 7.17a

  • Thoracic VertebraeThere are twelve vertebrae (T1-T12) all of which articulate with ribsMajor markings include two facets and two demifacets on the heart-shaped body, the circular vertebral foramen, transverse processes, and a lo