Avian osteology

• Domestic chicken (domestic fowl)


  • Important animal in veterinary practice
  • Need to be able to identify external features
  • Need to be familiar with parts of axial and appendicular skeleton
• Ornamental outgrowths of the skin


  Present on the head of the chicken
• Parts of the foot

  Shown in Figure 11
• Types of feathers present in birds

  • Contour feathers
  • Down feathers
• Wing and tail feathers


  • Help in flight
• Wing feathers attached to the skeleton

  Of the forearm
• Bones of birds


  • Light as well as strong to facilitate flight
  • Pneumatization of bones by air sacs which are extensions of the lung
• Exercises - External features and parts of the skeleton of the chicken
• Use the given figures to identify the major external features and parts of the skeleton in the specimens of birds present in the laboratory
• Observe the external features of the head and the foot of birds, and how flight feathers are attached to the wing when you visit the Veterinary Teaching Farm
• Compare the bones of the forelimb in the bird, dog, and cattle to see how they are adapted to the different modes of locomotion
• Contour feather


  Has three main parts: main shaft, barbs with barbules, and vane formed by the barbs
• Contour feather


  • Vanes in wing feathers are asymmetrical, with the external side narrower for aerodynamic flight
  • Barbs are closely ranked and connected by a large number of minute barbules to form the level of the vane
  • Neighbouring barbs are easily disconnected but reattach if brought together, as in preening/grooming
• Down feather


  More loosely arranged barbs that do not interlock to form a closed vane, creating an effective dead air space that insulates the body
• Specialized feathers


  • Some birds like pigeons and parrots have feathers that produce a keratin dust, which is spread over their plumage during preening
• Filoplume


  Hairlike feathers that remain after all other feathers are removed
• Bristle


  Modified contour feathers with a thick rachis at the base that tapers distally to a fine point, with a tuft of barbs at the tip
• After feather


  Smaller, narrower, and less rigid feathers that grow from the base of the main feathers along the shaft
• Primary and secondary flight feathers

  • Primary feathers are located on the distal end of the wing attached to the hand/fingers, are longer and narrower with a more pointed shape, and are primarily responsible for generating lift and thrust during flight
  • Secondary feathers are located on the forearm, are shorter and broader with a more rounded shape, and contribute to lift and stability but to a lesser extent