Skeletal System  Bones, joints, cartilage, ligaments  Two subdivisions  Axial  Bones forming the longitudinal axis of body  Appendicular  Bones of limbs and girdles  Bones, joints, cartilage, ligaments  Two subdivisions  Axial  Bones forming the longitudinal axis of body  Appendicular  Bones of limbs and girdles

Bone Functions  Support  Concrete of the body  Internal framework and anchor of soft organs  Protection  Protect internal organs  Rib cage - heart  Movement  Skeletal muscles attached to tendons move bones  Support  Concrete of the body  Internal framework and anchor of soft organs  Protection  Protect internal organs  Rib cage - heart  Movement  Skeletal muscles attached to tendons move bones  Storage  Fat in internal cavity of bone  Minerals - Ca, P  Blood cell formation  In marrow cavities of certain bones

Classification of Bones - Type  Compact  Dense, smooth, homogeneous  Spongy  Porous (open spaces)  Compact  Dense, smooth, homogeneous  Spongy  Porous (open spaces)

Classification of Bones - Shape  Long bones  Longer than they are wide  Shaft at both ends  Bones of limbs except small bones of hands and feet  Short bones  Pebble shaped  Mostly spongy  Wrist and ankle  Flat bones  Thin, flat, and curved  Layer of spongy sandwiched between two layers of compact  Skull, ribs, sternum  Long bones  Longer than they are wide  Shaft at both ends  Bones of limbs except small bones of hands and feet  Short bones  Pebble shaped  Mostly spongy  Wrist and ankle  Flat bones  Thin, flat, and curved  Layer of spongy sandwiched between two layers of compact  Skull, ribs, sternum

Classification of Bones - Shape  Irregular  Don’t fit into other categories  Vertebrae, hip  Irregular  Don’t fit into other categories  Vertebrae, hip

Structure of the long bone  Diaphysis  Shaft  Makes up length of bone  Periosteum  Covered by fibrous connective tissue  Sharpey’s fibers  Secures periosteum to bone  Diaphysis  Shaft  Makes up length of bone  Periosteum  Covered by fibrous connective tissue  Sharpey’s fibers  Secures periosteum to bone

Structure of the long bone  Epiphyses  Ends of long bone  Thin layer of compact bone enclosing an area filled with spongy bone  Articular (hyaline) cartilage covers surface  Epiphyses  Ends of long bone  Thin layer of compact bone enclosing an area filled with spongy bone  Articular (hyaline) cartilage covers surface

Structure of the long bone  Epiphyseal line  Remnant of epiphyseal plate  Epiphyseal plate  Flat line of hyaline cartilage  Lengthwise growth of long bones  By adulthood plate is replaced by bone  Epiphyseal line  Remnant of epiphyseal plate  Epiphyseal plate  Flat line of hyaline cartilage  Lengthwise growth of long bones  By adulthood plate is replaced by bone

Structure of the long bone  Shaft  In adults cavity stores adipose tissue (yellow marrow)  In children cavity is when RBCs are produced (red marrow)  In adults red marrow is in spongy bone of flat bones and epiphyses  Shaft  In adults cavity stores adipose tissue (yellow marrow)  In children cavity is when RBCs are produced (red marrow)  In adults red marrow is in spongy bone of flat bones and epiphyses

Bone Markings  Projections/Processes  Grow out from bone surface  (Table 5.1 Bone Markings)  Depressions or cavities  Indentations in the bone  (Table 5.1 Bone Markings)  Projections/Processes  Grow out from bone surface  (Table 5.1 Bone Markings)  Depressions or cavities  Indentations in the bone  (Table 5.1 Bone Markings)

Microscopic Bone Structure  Page 116 Figure 5.3  Compact bone  Routes for:  Nerves  blood vessels  nutrients  waste disposal  Page 116 Figure 5.3  Compact bone  Routes for:  Nerves  blood vessels  nutrients  waste disposal

Microscopic Bone Structure  Osteocytes  Mature bone cells  Lacunae  Space within matrix occupied by cells  Lamellae  Lacunae in concentric circles  Osteocytes  Mature bone cells  Lacunae  Space within matrix occupied by cells  Lamellae  Lacunae in concentric circles

Microscopic Bone Structure  Central (Haversian) canals  One or more blood vessels and nerves running lengthwise through matrix  Osteon/Haversian system  Functional unit of compact bone  Central canal and matrix rings  Central (Haversian) canals  One or more blood vessels and nerves running lengthwise through matrix  Osteon/Haversian system  Functional unit of compact bone  Central canal and matrix rings

Microscopic Bone Structure  Canaliculi  Transports nutrients between bone cells  Helps bone heal quickly  Perforating (Volkmann’s) canals  Communication pathway from outside to inside  Right angles to bone  Canaliculi  Transports nutrients between bone cells  Helps bone heal quickly  Perforating (Volkmann’s) canals  Communication pathway from outside to inside  Right angles to bone

Questions to ponder…  Where does the hardness of a bone come from?  Where do bones get their tensile strength and flexibility?

Questions to ponder…  Where does the hardness of a bone come from?  Where do bones get their tensile strength and flexibility?

Bone Formation, Growth, Remodeling  Skeleton made up of cartilage and bone  Ossification - bone formation 1.Hyaline cartilage model covered with bone matrix - osteoblasts - bone forming cells 2.Enclosed hyaline cartilage digested away, opens up meduallary cavity within newly formed bone  Skeleton made up of cartilage and bone  Ossification - bone formation 1.Hyaline cartilage model covered with bone matrix - osteoblasts - bone forming cells 2.Enclosed hyaline cartilage digested away, opens up meduallary cavity within newly formed bone

Bone Formation, Growth, Remodeling  Bone is dynamic and active tissue changing in response to: 1.Calcium levels in blood  Ca  Parathyroid hormone (PTH) released by PTH glands into blood activating osteoclasts (bone destroying cells)  Ca  deposited in bone matrix (hypercalcemia) 2.Pull of gravity and muscles on the skeleton.  Bone is dynamic and active tissue changing in response to: 1.Calcium levels in blood  Ca  Parathyroid hormone (PTH) released by PTH glands into blood activating osteoclasts (bone destroying cells)  Ca  deposited in bone matrix (hypercalcemia) 2.Pull of gravity and muscles on the skeleton.

Bone Fractures  Reduction  Realignment of broken bone ends  Closed - bone ends coaxed into normal position  Open - surgery performed, pins or wires  Immobilized after, 6-8 weeks  Reduction  Realignment of broken bone ends  Closed - bone ends coaxed into normal position  Open - surgery performed, pins or wires  Immobilized after, 6-8 weeks

Bone Fractures 1.Hematoma to close off blood vessels 2.Splinted by fibrocartilage callus Cartilage, bony, collagen fibers 3.Spongy bone callus, formed by osteoblasts and osteoclasts move into area and multiply 4.Bony callus is remodeled in response to mechanical stresses placed on it 1.Hematoma to close off blood vessels 2.Splinted by fibrocartilage callus Cartilage, bony, collagen fibers 3.Spongy bone callus, formed by osteoblasts and osteoclasts move into area and multiply 4.Bony callus is remodeled in response to mechanical stresses placed on it

Vertebral Column  Skull to Pelvis  Made up of 26 small, irregular bones  Before birth, 33 vertebrae  9 fuse to make two composite bones  Sacrum, coccyx  Skull to Pelvis  Made up of 26 small, irregular bones  Before birth, 33 vertebrae  9 fuse to make two composite bones  Sacrum, coccyx

Vertebral Column  Three divisions 1.Cervical 2.Thoracic 3.Lumbar  Three divisions 1.Cervical 2.Thoracic 3.Lumbar

Vertebral Column  Single vertebrae separated by intervertebral discs  Fibrocartilage  Herniated disc?  Disc dries out  Single vertebrae separated by intervertebral discs  Fibrocartilage  Herniated disc?  Disc dries out

Vertebral Column  All vertebrae have six common structures 1.Body  disc-like appearance  Faces anteriorly to the vertebral column 2.Vertebral arch  Joins all processes  Posterior extension 3.Vertebral foramen  Canal for spinal cord 4.Transverse processes  Two lateral projections branching off vertebral arch 5.Spinous process  Single projection from posterior of vertebra 6.Superior & Inferior articular processes  Paired projections lateral to vertebral foramen  All vertebrae have six common structures 1.Body  disc-like appearance  Faces anteriorly to the vertebral column 2.Vertebral arch  Joins all processes  Posterior extension 3.Vertebral foramen  Canal for spinal cord 4.Transverse processes  Two lateral projections branching off vertebral arch 5.Spinous process  Single projection from posterior of vertebra 6.Superior & Inferior articular processes  Paired projections lateral to vertebral foramen

Vertebral Regions  Sacrum  Fusion of 5 vertebrae  Structure 1.Alae - wing like structures 2.Sacral crest - spinous projections running down dorsal midline 3.Sacral canal - vertebral canal continues inside sacrum  Sacrum  Fusion of 5 vertebrae  Structure 1.Alae - wing like structures 2.Sacral crest - spinous projections running down dorsal midline 3.Sacral canal - vertebral canal continues inside sacrum

Bony Thorax (thoracic cage)  Structure  Sternum  Ribs  Thoracic vertebrae  Function  Protective cage around heart, lungs, and important blood vessels  Structure  Sternum  Ribs  Thoracic vertebrae  Function  Protective cage around heart, lungs, and important blood vessels

Sternum (breastbone)  Flat bone  Made up of three fused bones  Manubrium  Body  Xiphoid process  Interesting tidbit  Close to surface  Easy to obtain marrow  Flat bone  Made up of three fused bones  Manubrium  Body  Xiphoid process  Interesting tidbit  Close to surface  Easy to obtain marrow

Ribs  12 pairs of ribs  Males and females have same #  Articulate to vertebrae, curve downward toward anterior surface  Space between ribs contain intercostal muscles  True ribs  First 7 attached to sternum by costal cartilage  False ribs  Next 5 pairs, attach indirectly or not at all to sternum  Floating ribs  Last two pairs, no attachment  12 pairs of ribs  Males and females have same #  Articulate to vertebrae, curve downward toward anterior surface  Space between ribs contain intercostal muscles  True ribs  First 7 attached to sternum by costal cartilage  False ribs  Next 5 pairs, attach indirectly or not at all to sternum  Floating ribs  Last two pairs, no attachment