This is the cartilage-covered, v-shaped groove at the distal end of the anterior femur. The groove consists of the inner walls of the lateral and medial femoral condyles much as a valley flanked by two mountains. In normal knees, the lateral condyle (and therefore the lateral wall of the trochlea) is always higher (protrudes farther anteriorly) than the lateral one.
The Intercondylar Notch
The name given to the vault-like space between the two femoral condyles. The anterior portion of its roof is actually the distal-most portion of the trochlea. The importance of this roof lies in the fact that it is often partially removed during the "notchplasty" portion of an anterior cruciate ligament reconstruction - with unknown long term effects on the patella. When seen in profile on a lateral x-ray the roof appears as a line known as Blumensaat’s line. This line along with the longitudinal axis of the distal femur subtends an angle which averages 45 degrees but varies between 25 and 60 degrees.