Nepedia
Back to Discover
Advanced Reader
🧬

Femur

life science Maturity 11-13 Next article →

The femur is the bone located in the human thigh.

Long Bone (Femur)
Long Bone (Femur)

It occupies the region of the lower limb between the hip and the knee. In humans, the femur is the longest and thickest bone in the entire body. It is also considered by some measures to be the strongest bone. Because it is the only bone in the upper leg, it plays a vital role in movement. It serves as a primary attachment point for muscles that move the hip and knee joints.

Gray243
Gray243

Structurally, the femur is classified as a long bone. This means it consists of a central shaft called the diaphysis and two ends called epiphyses. The proximal extremity, or the top end, is the thinnest part of the bone. It contains the femoral head, which is two-thirds of a sphere. This head fits into the acetabulum, a socket in the pelvic bone, to create the hip joint. The head is connected to the shaft by the neck, or collum. This neck is typically 4 to 5 cm long. The angle between the neck and the shaft is usually about 130 degrees. This angle can change with age, averaging 150 degrees in infants and 120 degrees in the elderly.

The bone also features two prominent projections called trochanters. The greater trochanter is a large, almost box-shaped structure on the lateral side. It is easy to feel through the skin. The lesser trochanter is a smaller, cone-shaped extension at the base of the neck. These two structures are joined by the intertrochanteric crest on the back and the intertrochanteric line on the front. Between these trochanters, the bone is quite rough to allow for muscle attachment. The shaft itself is almost cylindrical and slightly arched. It features a prominent longitudinal ridge on the back called the linea aspera. This ridge helps strengthen the bone and provides surfaces for muscle connection.

The distal extremity, or the bottom end, is the thickest part of the femur.

Gray246
Gray246

It has a somewhat cuboid shape and features two large, oblong bumps called condyles. The lateral condyle is broader and more prominent than the medial condyle. Between these condyles is a deep notch called the intercondylar fossa. On the front of the bone, a smooth depression called the patellar surface allows the bone to connect with the patella, or kneecap. Each condyle also has a smaller elevation called an epicondyle. These epicondyles serve as attachment points for important knee ligaments. For example, the medial epicondyle connects to the tibial collateral ligament.

Gray348
Gray348

Development of the femur begins very early in life. It starts to form from limb buds during the fourth week of development. This process involves interactions between the ectoderm and the underlying mesoderm. By the sixth week, chondrocytes create a model made of hyaline cartilage. The bone then undergoes endochondral ossification, which is the process of turning cartilage into bone. Primary ossification centers appear in the femur by the 12th week of development. Interestingly, the development of the hindlimb lags behind the forelimb by one to two days.

The femur is essential for the mechanical function of the leg. It acts as an axis for the three fascial compartments of the thigh. These compartments are the anterior, medial, and posterior sections. Each compartment contains a different group of muscles and has its own nerve and blood supply. In total, 23 individual muscles either originate from or insert onto the femur.

Femur front
Femur front
Femur back
Femur back

These muscles include the gluteus maximus, which attaches to the gluteal tuberosity, and the vastus lateralis, which originates from the greater trochanter. This complex muscle attachment system allows for controlled walking and standing.

In science, the femur is a highly significant tool for anthropologists. On average, the length of the femur accounts for 26.74% of a person's total height. This ratio remains consistent across most ethnic groups with very little variation. Because of this, researchers can use the femur to estimate a person's height from an incomplete skeleton. This makes the bone a reliable piece of evidence when studying ancient human remains. Understanding the femur also helps doctors manage injuries. For example, a fracture in the femoral neck or shaft is often classified as a hip fracture. These injuries can be managed in emergency settings using a traction splint.

711 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (7)
File:Gray243.png
Gray243.png
File:Long Bone (Femur).png
Long Bone (Femur).png
File:Gray246.png
Gray246.png
File:Gray348.png
Gray348.png
File:Femur front.png
Femur front.png
File:Femur back.png
Femur back.png
File:Identification-Classification-and-Growth-of-Moa-Chicks-(Aves-Dinornithiformes)-from-the-Genus-pone.0099929.g002.jpg
Identification-Classification-and-Growth-o...
More to explore

✨ What else?

Related topics you might enjoy

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.