The Skeletal System

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The Skeletal System
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Skeletal system

• Is made up of hard tissues like bone and
  cartilages.
• Gives form and shape to animal body
• The skeleton of a living animal is made up living
  structures of bones.
• The bones have blood vessels, lymphatic vessels
  and nerves.
• They are subject to disease, repair themselves
  and adjust to changes during stress.

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Functions of Bones

• 1.Protection of some vital organs from the
  external damages -important function
• CNS is protected by the skull and vertebral
  column the heart and lungs by rib cage and
  pelvis protects the internal parts of urogenital
  system.
• 2.Rigidity and form to the body animals without
  a skeleton of some type have little or no regular
  form. Gives a basis for the external structure
  and appearance of most animals.

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• 3.Act as lever in the vertebrates, locomotion,
  defense, offense, grasping, and other activities
  .Almost without exception, these levers are made
  of bone and are integral parts of skeleton.
• 4.Storage of minerals -dynamic storage area for
  minerals, particularly calcium and phosphorous.
• 5.Site for blood formation blood formation is
  not strictly a function of bone proper, but of
  the marrow found within the marrow cavity of long
  bones and within the spongy substance of all
  young bones.

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Classification of bones

• Any bone may be classified into one of the
  following groups  
• I. Long bones
• relatively cylindrical in shape with two
  extremities called epiphyses.
• Metaphysis between each epiphysis and the
  diaphysis.
• A long bone grows in length only at the
  epiphyseal cartilage which is located within the
  metaphysis.
•  

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Long bone
Epiphysis
Metaphysis
Medullary Cavity
Diaphysis
Metaphysis
Epiphysis
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• Examples of long bones - pectoral limb, humerus,
  radius, ulna, metacarpals, phalanges pelvic
  limb, femur, fibula, tibia, metatarsals and
  phalanges.
• 2. Short bones
• Somewhat cuboid in shape i.e approximately equal
  in all dimensions.
• No marrow cavity.
• Found in complex joints such as the carpus (knee)
  and tarsus (hock).
• Example of short bones Patella.

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• Function - for variety of movement - absorption
  of shock
• 3.Flat bones
• relatively thin and expanded in two dimensions.
• Consist of two plats of compact substance, lamina
  externa and lamina interna,
• Separated by diploe.
• Example -frontal base of skull, scapula and
  pelvic bones
• Functions - protects vital organs such as brain,
  the heart and lungs.
• - many provide large areas for muscle
  attachment.

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• 4. Sesamoid bones they are developed along the
  course of tendons. Example Patella (knee cap) is
  the largest sesamoid in the body.
• Functions -reduces friction or change the course
  of tendons.
• - may change the angle of the pull of
  muscles and this give a greater
  mechanical advantage.
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• 5. Pneumatic bones they contain air spaces or
  sinuses that communicate with the exterior.
  Example long bones of bird, frontal bones and
  maxillary bones of the skull.
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• 6. Irregular bones
• are unpaired bones located on the median plane
  and include the vertebrae and some of the
  unpaired bones of the skull.
• Functions - protection, support and muscle
  attachment.

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TWO PARTS OF SKELETAL SYSTEM

• For better understanding the skeletal system can
  be divided into two part
• Axial skeleton
• Appendicular skeleton.
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• 1.AXIAL SKELETON
• is made up of skull, and vertebral column sternum
  and ribs. The table below indicates the bones of
  the axial skeleton by regions.

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Axial Skeleton of cattle
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• Skull
• Forms basis for head
• Made of - cranial bones
• - Facial bones
• Protects brain
• Support sense organs
• Digestive respiratory system starts

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Skull of cattle
Cranial bones
Diploe
Facial Bones
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• Vertebral column
• Made of unpaired irregular bones

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• Divided into
• Cervical vertebrae (C)
• Thoracic vertebrae (T)
• Lumbar vertebrae (L)
• Sacral vertebrae (S)
• Coccygeal vertebrae (Cd)

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Vertebral formulaCow C7 T13 L6 S5 cd18-20
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Sternum
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Ribs
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• 2.APPENDICULAR SKELETON
• Is made of
• Pectoral limb or fore limb
• Pelvic limb or hind limb

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Pelvic Limb
Pelvis
Femur
Tibia fibula
Tarsus
Metatarsus
digits
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Avian skeleton
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Skeleton of goat
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Skeleton of pig