Bone: Femur
Anterior view of the femur
Latin	os femoris, os longissimum
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 (pl. femurs or femora), or thigh bone, is the most proximal (closest to the center of the body) 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 rear legs. The femur is the largest bone in the human body. The head of the femur articulates with the acetabulum. By most measures the femur is one of the strongest bones in the body.

Other species[link]

In primitive tetrapods, the main points of muscle attachment along the femur are the internal trochanter and fourth 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.^[1]

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.

Terminology in invertebrate zoology[link]

In invertebrate zoology the name femur appears in Arthropodology. 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. The two basal segments preceding the femur are the coxa and trochanter. This convention is not followed in Carcinology but it applies in Arachnology and Entomology. In Myriapodology another segment, the prefemur, connects the trochanter and femur.

Fractures[link]

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.

Etymology[link]

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

Additional images[link]

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  Knee diagram

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  Upper extremity of right femur viewed from behind and above.

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  Right femur. Anterior surface.

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  Right femur. Posterior surface.

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  Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis.

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  Right knee-joint. Posterior view.

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  Left knee-joint from behind, showing interior ligaments.

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  Sagittal section of right knee-joint.

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  Capsule of right knee-joint (distended). Lateral aspect.

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  Capsule of right knee-joint (distended). Posterior aspect.

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  Cross-section through the middle of the thigh.

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  Deep muscles of the medial femoral region.

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  Posterior view.

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  Anterior view.

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  Superior epiphysis - anterior view

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  Superior epiphysis - posterior view

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  Inferior epiphysis - posterior view

References[link]

External links[link]

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

• Image with major components labeled at v^{[dead link]}
• Cross section at UV pembody/body18b