femur, femora

From Latin femur, femoris, the thigh.

femur noun, plural femora or femurs, adjective femoral - the thigh, a long stout joint, the third- and typically the longest- segment of the insect leg. It is also the most variable in shape, and may be modified for digging, jumping (Orthoptera), or prey capture (mantids). Moving outward from the body it comes after the trochanter, and before the tibia.

It moves freely, and is composed of three pieces, the separation of which is marked by strong sutural lines: these are called the first, second, and third joints of the femur - femoris caput; femoris trochanter, and femoris scapus. When two parts only are discernible, they're the second and third; when only one it's the third, and is by itself called the thigh, or femur.

See the diagram of insect and spider legs above.

For the three pairs of legs of insects, the femora of the foremost pair are referred to as the profemora, the middle as the mesofemora and the rearmost as the metafemora.