1.  Field of the Invention
relates to an ultrasonic
The present invention relates to an ultrasonic treatment apparatus which is used in combination with, e.g., an endoscope so as to break a stone in a body or to resect a tissue in a body by emulsifying it. 
2.  Description of the Related Art
A typical ultrasonic treatment apparatus comprises an ultrasonic oscillator and a vibration transmission member for transmitting ultrasonic vibrations generated by the oscillator to a portion to be treated. 
In using this ultrasonic treatment apparatus for a surgical operation, in order to prevent a normal tissue from being adversely affected by heat which is generated by vibrations when the vibration transmission member is brought into contact with a portion other than a morbid portion, or to prevent generation of heat due to vibrations of the vibration transmission member, a technique of covering the vibration transmission member with a sheath and causing a perfusion liquid to flow between the vibration transmission member and the sheath has been proposed.  Typical examples of this technique are disclosed in U.S. Pat.  Nos.  3,805,787 and 4,425,115. 
Published Unexamined Japanese Patent Application No.  61-159953 discloses an ultrasonic treatment apparatus which is used in combination with an endoscope and has a vibration transmission member to be inserted into the channel of the endoscope. 
In ultrasonic treatment apparatuses disclosed in U.S. Pat.  Nos.  3,805,787 and 4,425,115, a perfusion liquid is supplied to a cover which covers an ultrasonic oscillator and to a portion near the connecting portion of the cover and the sheath.  In the ultrasonic treatment apparatus disclosed in Published Unexamined Japanese
Patent Application No.  61-159953, when the apparatus is to be used in combination with an endoscope, a portion between the channel of the endoscope and the vibration transmission member is sealed by a rubber plug or the like fitted in the channel opening of the endoscope, and a perfusion liquid is supplied from a portion near the sealed portion into the channel.