Study of diaphyseal nutrient foramina in human long bones.

A study was done to determine the number, size, direction, exact site and position of the nutrient foramina in human long bones. The position of all nutrient foramina observed was on the flexor aspect and was more or less around a fixed area, but the exact spot varied considerably. Two foramina were much more frequent in the femur, clavicle and humerus than in the other long bones. Three and four nutrient foramina have also been observed in few femora, clavicles and ulnae. Absence of a foramen has been observed in few humeri and radii. Variations have been observed in the direction of nutrient foramina only in lower limb bones. The nutrient foramina in long bones have been described as being directed towards the elbow and away from the knee. Our observations support this assumption except in 0.5% femora, 3.5% tibiae and 9.5% fibulae. Periosteal, muscular and vascular theories are discussed for the normal and abnormal direction of the foramina; the vascular theory offers the best explanation of all reported anomalies as well as of the normal fashioning of the nutrient canals.