Question

Upward and downward movements of throat during buccopharyngeal respiration of frog are by which of the following set of muscles?

• A. Mylohyoid and geniohyoid
• B. Sternohyal and petrohyal
• C. Retractor bulbi and levator bulbi
• D. None of the above

Answer 1

The correct option is B Sternohyal and petrohyal

In vertebrates filling of lungs can take place with the use of pressure pump as in amphibians or a suction pump as in most reptiles, birds and mammals. A frog fills its lungs by taking air into its mouth cavity, closing its mouth and nostrils and pressing air into its lungs by elevating the floor of its mouth. As a result of this filling mechanism, a frog can continue to take in repeated volumes of air several times in sequence without letting air out. Amphibians lack ribs and hence use floor of the buccal cavity to force air in and out of the lungs. Frogs and toads modify 2nd, 3rd and 4th visceral arches to produce a plate-like hyobranchial apparatus that lies in the floor of oral cavity and is connected to squamosal bone of skull by petrohyal muscle and to sternum by sternohyal muscle. One breathing cycle is completed in four steps in anurans that is affected by contraction of these two muscles.