|Origins||Gastrocnemius, vastus lateralis, vastus medialis and vastus intermedius|
|Insertions||Gluteus maximus, gluteus medius, gluteus minimus, iliopsoas, lateral rotator group, adductors of the hip|
|Articulations||hip: acetabulum of pelvis superiorly|
|Latin||Os femoris, os longissimum|
By most measures the two (left and right) femurs are the strongest bones of the body, and in humans, the longest.
The femur is the only bone in the upper leg.
The angle of convergence of the femora is a major factor in determining the femoral-tibial angle.
Human females have wider pelvic bones, causing their femora to converge more than in males.
In the condition genu valgum (knock knee) the femurs converge so much that the knees touch one another.
The opposite extreme is genu varum (bow-leggedness).
In the general population of people without either genu valgum or genu varum, the femoral-tibial angle is about 175 degrees.
The femur is the longest and, by some measures, the strongest bone in the human body.
This depends on the type of measurement taken to calculate strength.
Some strength tests show the temporal bone in the skull to be the strongest bone.
The femur length on average is 26.74% of a person's height, a ratio found in both men and women and most ethnic groups with only restricted variation, and is useful in anthropology because it offers a basis for a reasonable estimate of a subject's height from an incomplete skeleton.
Main article: Upper extremity of femur
The neck is 4–5 cm.
long and the diameter is smallest front to back and compressed at its middle.
The collum forms an angle with the shaft in about 130 degrees.
This angle is highly variant.
The transition area between the head and neck is quite rough due to attachment of muscles and the hip joint capsule.
The greater trochanter is almost box-shaped and is the most lateral prominent of the femur.
The highest point of the greater trochanter is located higher than the collum and reaches the midpoint of the hip joint.
The greater trochanter can easily be felt.
The trochanteric fossa is a deep depression bounded posteriorly by the intertrochanteric crest on the medial surface of the greater trochanter.
The lesser trochanter is a cone-shaped extension of the lowest part of the femur neck.
A slight ridge is sometimes seen commencing about the middle of the intertrochanteric crest, and reaching vertically downward for about 5 cm.
along the back part of the body: it is called the linea quadrata (or quadrate line).
About the junction of the upper one-third and lower two-thirds on the intertrochanteric crest is the quadrate tubercle located.
The size of the tubercle varies and it is not always located on the intertrochanteric crest and that also adjacent areas can be part of the quadrate tubercle, such as the posterior surface of the greater trochanter or the neck of the femur.
In a small anatomical study it was shown that the epiphyseal line passes directly through the quadrate tubercle.
Main article: Body of femur
The body of the femur (or shaft) is long, slender and almost cylindrical in form.
It is a little broader above than in the center, broadest and somewhat flattened from before backward below.
It is slightly arched, so as to be convex in front, and concave behind, where it is strengthened by a prominent longitudinal ridge, the linea aspera which diverges proximally and distal as the medial and lateral ridge.
Besides the linea aspera the shaft has two other bordes; a lateral and medial border.
These three bordes separates the shaft into three surfaces: One anterior, one medial and one lateral.
The third trochanter is a bony projection occasionally present on the proximal femur near the superior border of the gluteal tuberosity.
When present, it is oblong, rounded, or conical in shape and sometimes continuous with the gluteal ridge.
A structure of minor importance in humans, the incidence of the third trochanter varies from 17–72% between ethnic groups and it is frequently reported as more common in females than in males.
Main article: Lower extremity of femur
It is somewhat cuboid in form, but its transverse diameter is greater than its antero-posterior (front to back).
It consists of two oblong eminences known as the condyles.
Anteriorly, the condyles are slightly prominent and are separated by a smooth shallow articular depression called the patellar surface.
Posteriorly, they project considerably and a deep notch, the Intercondylar fossa of femur, is present between them.
The lateral condyle is the more prominent and is the broader both in its antero-posterior and transverse diameters.
The medial condyle is the longer and, when the femur is held with its body perpendicular, projects to a lower level.
When, however, the femur is in its natural oblique position the lower surfaces of the two condyles lie practically in the same horizontal plane.
The condyles are not quite parallel with one another; the long axis of the lateral is almost directly antero-posterior, but that of the medial runs backward and medialward.
Their opposed surfaces are small, rough, and concave, and form the walls of the intercondyloid fossa.
This fossa is limited above by a ridge, the intercondyloid line, and below by the central part of the posterior margin of the patellar surface.
The posterior cruciate ligament of the knee joint is attached to the lower and front part of the medial wall of the fossa and the anterior cruciate ligament to an impression on the upper and back part of its lateral wall.
The articular surface of the lower end of the femur occupies the anterior, inferior, and posterior surfaces of the condyles.
Its front part is named the patellar surface and articulates with the patella; it presents a median groove which extends downward to the intercondyloid fossa and two convexities, the lateral of which is broader, more prominent, and extends farther upward than the medial.
Each condyle is surmounted by an elevation, the epicondyle.
Main article: Limb development
As the femur is the only bone in the thigh, it serves as an attachment point for all the muscles that exert their force over the hip and knee joints.
In all, 23 individual muscles either originate from or insert onto the femur.
A femoral fracture that involves the femoral head, femoral neck or the shaft of the femur immediately below the lesser trochanter may be classified as a hip fracture, especially when associated with osteoporosis.
Femur fractures can be managed in a pre-hospital setting with the use of a traction splint.
In primitive tetrapods, the main points of muscle attachment along the femur are the internal trochanter and third trochanter, and a ridge along the ventral surface of the femoral shaft referred to as the adductor crest.
The neck of the femur is generally minimal or absent in the most primitive forms, reflecting a simple attachment to the acetabulum.
The greater trochanter was present in the extinct archosaurs, as well as in modern birds and mammals, being associated with the loss of the primitive sprawling gait.
The lesser trochanter is a unique development of mammals, which lack both the internal and fourth trochanters.
The adductor crest is also often absent in mammals or alternatively reduced to a series of creases along the surface of the bone.
Structures analogous to the third trochanter are present in mammals, including some primates.
Main article: Arthropod leg
The usage is not homologous with that of vertebrate anatomy; the term "femur" simply has been adopted by analogy and refers, where applicable, to the most proximal of (usually) the two longest jointed segments of the legs of the arthropoda.
In myriapodology another segment, the prefemur, connects the trochanter and femur.
Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Femur.