femur

For the invertebrate femur, see Arthropod leg.

Bone: Femur
Anterior view of the femur
Gray's	subject #59 242
Origins	Gastrocnemius , Vastus lateralis, Vastus medialis, Vastus intermedius
Insertions	tensor fasciae latae, gluteus medius, gluteus minimus, Gluteus maximus, Iliopsoas
Articulations	hip: acetabulum of pelvis superiorly knee: with the tibia and patella inferiorly
MeSH	Femur

The femur, or thigh bone, is the most proximal (closest to the body) bone of the leg in vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs.

Human anatomy

In human anatomy, the femur is the longest and largest bone. Along with the temporal bone of the skull, it is one of the two strongest bones in the body. The average adult human femur is 48 centimeters (19 in) in length and 2.34 cm (0.92 in) in diameter and can support up to 30 times the weight of an adult.^[1] It forms part of the hip (at the acetabulum) and part of the knee. There are four eminences, or protuberances, in the human femur: the head, the greater trochanter, the lesser trochanter, and the lower extremity. They appear at various times from just before birth to about age 14. Initially, they are joined to the main body of the femur with cartilage, which gradually becomes ossified until the protuberances become an integral part of the femur bone, usually in early adulthood.

The intercondylar fossa is present between the condyles at the distal end of the femur. In addition to the intercondylar eminence on the tibial plateau, there is both an anterior and posterior intercondylar fossa (area), the sites of anterior cruciate and posterior cruciate ligament attachment, respectively.

Evolutionary variation

In vertebrates with four legs, the femur is found only in the rear legs. Some species of whales^[2], snakes, and other non-walking vertebrates have vestigial femurs. One of the earliest known vertebrates to have a femur is the Eusthenopteron, a prehistoric lobe-finned fish from the Late Devonian period. In invertebrates, the name femur is also given to the most proximal full-length jointed segment of the legs of some arthropods such as spiders.

Etymology

The word femur is Latin for thigh. Theoretically in strict usage, femur bone is more proper than femur, as in classical Latin femur means "thigh", and os femoris means "the thigh's bone".

In medical Latin its genitive is always femoris, but in classical Latin its genitive is often feminis, and should not be confused with case forms of femina, which means "woman".

Additional images

Knee diagram	Upper extremity of right femur viewed from behind and above.	Right femur. Anterior surface.	Right femur. Posterior surface.
Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis.	Right knee-joint. Posterior view.	Left knee-joint from behind, showing interior ligaments.	Sagittal section of right knee-joint.
Capsule of right knee-joint (distended). Lateral aspect.	Capsule of right knee-joint (distended). Posterior aspect.	Cross-section through the middle of the thigh.	Deep muscles of the medial femoral region.

References

External links

Look up femur or thighbone in Wiktionary, the free dictionary.

• Image with major components labeled at v
• Femoral fractures at aofoundation.org
• Cross section at UV pembody/body18b