Reisiluu

Reisiluu, Finnish for the femur, is the thigh bone and the longest bone in the human skeleton. It extends from the hip to the knee and serves as a primary weight-bearing structure and a lever for movements such as walking and running. The proximal end articulates with the pelvis at the hip joint through the femoral head, which sits within the acetabulum, and is connected to the shaft by the femoral neck. The greater and lesser trochanters provide attachment sites for hip and thigh muscles. The shaft, or diaphysis, is cylindrical and composed largely of cortical bone surrounding a medullary cavity that contains bone marrow. The distal end presents the medial and lateral condyles that articulate with the tibia at the knee, with the patellar surface on the anterior aspect and the intercondylar fossa on the posterior aspect. The linea aspera runs along the posterior midline of the shaft as a major site for muscle attachment.

Blood supply to the Reisiluu is mainly via the medial and lateral circumflex femoral arteries, with contributions from the perforating branches of the profunda femoris artery; the femoral artery itself becomes the popliteal artery after passing through the adductor hiatus. The bone receives innervation from nerves that supply the surrounding muscles, including branches of the femoral nerve for the anterior compartment and contributions from other nerves for adjacent regions. In development, growth occurs at the proximal and distal growth plates near the ends of the bone, contributing to increases in length during childhood and adolescence.

Clinical considerations include fractures of the Reisiluu, which can be intracapsular (near the hip joint) or extracapsular (around the neck or distal end). Hip fractures are particularly common in older adults and may require surgical intervention such as fixation or arthroplasty.