Introduction
The thigh bone (also: femur) is the longest bone in the human body and provides a connection between the pelvis and the lower leg bone. It is connected to the other bones by the hip or knee joint. At the end of the hip, the thigh bone has a spherical shape, which is why it is called femoral head (also: caput femoris).
The end which points to the knee has a more fork-shaped structure and ends in two cylindrical structures, the joint gnarl (also: Epicondylus medialis and Epicondylus lateralis). The shorter part points towards the hip joint and the longer towards the knee. The connection between the short and the longer part is called the femoral neck (also: collum femoris).
This area is particularly at risk for bone fractures due to the physical forces acting on it. Also important to mention are the two trochanteric mounds (also: greater trochanter and lesser trochanter), which are located directly at the transition from the femoral neck to the long part of the femur (also: corpus femoris). These bumped structures are the starting point for many muscles in this area.
The same function is performed by a rough, linear elevation (also: Linea aspera) on the back of the long part of the femur. Functionally, the thigh bone must on the one hand support the weight of the human body, withstanding both compressive and tensile stress. On the other hand, it must allow a certain degree of mobility in relation to the joint surfaces of the adjacent bones in order to enable the lower extremity to perform more functions. All in all, therefore, a versatile task.
Waist of the femoral neck
The term “waist” refers to the slimming of a structure at a specific point. In the context of the femoral neck, this means the anatomically determined slimming of the femoral neck in relation to the rest of the femur or the long part of the femur. The waistline at this point allows a greater range of movement of the thigh, but above all a better flexion and rotation in the hip joint. If, on the other hand, the waist is not sufficiently pronounced, for example due to a congenital form disorder at this point, this can lead to the clinical picture of CAM impingement. These patients then primarily experience discomfort during flexion in the hip joint.