Patent ID: 7661162

Claim:
A surgical head clamp comprising: an essentially U-shaped retaining clip with a connecting bar and a first holder arm and a second holder arm extending in a same direction in a plane of said U-shaped retaining clip at ends of said connecting bar, said first holder arm having a first arm end with a first bearing bore and said second holder arm having a second arm end with a second bearing bore having an inner wall with a smooth cylindrical surface and with two balls arranged in a diametrically opposed, axially fixed manner in said inner wall, said first bearing bore being coaxial to said second bearing bore; a first mandrel holders mounted adjustably in said first bearing bore and pivotably fastened at a first bearing part of said first arm end, said first bearing part being adjustable around a common bearing shaft; a second mandrel holder mounted adjustably in said second bearing bore, said second mandrel holder including a threaded spindle provided with an external thread for adjustment and an axial bore and said second mandrel holder including a guide shank provided with a socket bore on a front side, said guide shank being mounted coaxially to said common bearing shaft in a spring-mounted manner in said axial bore of said threaded spindle, said threaded spindle being adjustably mounted in said second bearing bore of said second arm end, said external thread comprising a ball thread with an arcuate-segment profile, said two balls meshing as contact elements with said arcuate-segment profile; an adjustable locking lever connected to said U-shaped retaining clip and having a locked position, said balls being held in contact with said ball thread by means of said adjustable locking lever in the locked position thereof, and said balls being brought out of contact with said threaded spindle in another position of said locking lever in order to make said threaded spindle freely displaceable in said second bearing bore.