Femur - anterior view2.png
Position of femur (shown in red)
Left femur seen from behind.
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
knee: with the tibia and patella inferiorly
Latin Os femoris, os longissimum
MeSH A02.835.232.500.247
TA A02.5.04.001
FMA 9611
Anatomical terms of bone

The femur ( r/, pl. femurs or femora ə/ [1] [2]) or thigh bone, is the most proximal (closest to the hip joint) bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in the hindlimbs. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and kneecap forming the knee joint. By most measures the femur is the strongest bone in the body. The femur is also the longest bone in the human body.


The femur is the only bone in the thigh. The two femurs converge medially toward the knees, where they articulate with the proximal ends of the tibiae. 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. [3]

The femur is the longest and, by most measures, the strongest bone in the human body. Its length on average is 26.74% of a person's height, [4] 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.

The femur is categorised as a long bone and comprises a diaphysis (shaft or body) and two epiphyses (extremities) that articulate with adjacent bones in the hip and knee. [3]

Upper part

The upper extremity of right femur viewed from behind and above, showing head, neck, and the greater and lesser trochanter

The upper or proximal extremity (close to the torso) contains the head, neck, the two trochanters and adjacent structures. [3]

The head of the femur, which articulates with the acetabulum of the pelvic bone, comprises two-thirds of a sphere. It has a small groove, or fovea, connected through the round ligament to the sides of the acetabular notch. The head of the femur is connected to the shaft through the neck or collum. 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. In the infant it is about 150 degrees and in old age reduced to 120 degrees on average. An abnormal increase in the angle is known as coxa valga and an abnormal reduction is called coxa vara. Both the head and neck of the femur is vastly embedded in the hip musculature and can not be directly palpated. In skinny people with the thigh laterally rotated, the head of the femur can be felt deep as a resistance profound (deep) for the femoral artery. [3]

The transition area between the head and neck is quite rough due to attachment of muscles and the hip joint capsule. Here the two trochanters, greater and lesser trochanter, are found. 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 medial surface of the greater trochanter. The lesser trochanter is a cone-shaped extension of the lowest part of the femur neck. The two trochanters are joined by the intertrochanteric crest on the back side and by the intertrochanteric line on the front. [3]

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 tubercel, 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 epiphysial line passes directly through the quadrate tubercle. [5]


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 proximal and distal as the medial and lateral ridge. Proximal the lateral ridge of the linea aspera becomes the gluteal tuberosity while the medial ridge continues as the pectineal line. 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. Due to the vast musculature of the thigh the shaft can not be palpated. [3]

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. [6] 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. [7]

Lower part

Lower extremity of right femur viewed from below.
Left knee joint from behind, showing interior ligaments.

The lower extremity of the femur (or distal extremity) is larger than the upper extremity. 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. [3]

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. [3]

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. [3]

Each condyle is surmounted by an elevation, the epicondyle. The medial epicondyle is a large convex eminence to which the tibial collateral ligament of the knee-joint is attached. At its upper part is the adductor tubercle and behind it is a rough impression which gives origin to the medial head of the gastrocnemius. The lateral epicondyle which is smaller and less prominent than the medial, gives attachment to the fibular collateral ligament of the knee-joint. [3]


The femur develops from the limb buds as a result of interactions between the ectoderm and the underlying mesoderm, formation occurs roughly around the fourth week of development. [8]

By the sixth week of development, the first hyaline cartilage model of the femur is formed by chondrocytes. Endochondral ossification begins by the end of the embryonic period and primary ossification centers are present in all long bones of the limbs, including the femur, by the 12th week of development. The hindlimb development lags behind forelimb development by 1–2 days.

Other Languages
العربية: عظم فخذ
Aymar aru: Chara ch'aka
azərbaycanca: Bud sümüyü
বাংলা: ঊর্বস্থি
башҡортса: Бот һөйәге
български: Бедрена кост
bosanski: Bedrena kost
brezhoneg: Askorn morzhed
català: Fèmur
čeština: Stehenní kost
Ελληνικά: Μηριαίο οστό
español: Fémur
Esperanto: Femurosto
euskara: Izterrezur
français: Fémur
Gaeilge: Féimear
galego: Fémur
한국어: 넙다리뼈
hrvatski: Bedrena kost
Ido: Femuro
Bahasa Indonesia: Tulang paha
isiXhosa: I-femur
italiano: Femore
עברית: עצם הירך
қазақша: Ортан жілік
кырык мары: Ӓрдӹлу
Latina: Femur
lietuvių: Šlaunikaulis
magyar: Combcsont
македонски: Ивер
Nederlands: Dijbeen
नेपाल भाषा: फिमर
日本語: 大腿骨
norsk: Lårben
polski: Kość udowa
português: Fêmur
română: Femur
Scots: Thee bane
Simple English: Femur
slovenščina: Stegnenica
کوردی: ئێسکی ڕان
srpskohrvatski / српскохрватски: Bedrena kost
suomi: Reisiluu
svenska: Lårben
తెలుగు: తుంటి ఎముక
Türkçe: Femur
українська: Стегнова кістка
文言: 股骨
粵語: 股骨
中文: 股骨