Femur Bone Anatomy

Introduction

Femur Bone Anatomy

The femur, commonly known as the thigh bone, is the longest, strongest, and heaviest bone in the human body. Located in the upper leg, it extends from the hip joint down to the knee joint, playing a crucial role in supporting the body’s weight and enabling a wide range of movements, including walking, running, and jumping.

Its unique structure provides leverage and stability, with the femoral head fitting into the hip socket to form a ball-and-socket joint, allowing for a smooth, multi-directional movement. Due to its weight-bearing function, the femur is particularly resilient but can be vulnerable to fractures, especially in high-impact injuries or conditions like osteoporosis.

Structure of Femur Bone

The proximal ends of the tibiae articulate with the two femurs as they converge medially toward the knees. The femora of female humans converge more than those of men due to the thickness of their pelvic bones. The femurs converge so far that the knees contact in genu valgum, also known as knock knee.

Upper part

The head, neck, two trochanters, and surrounding components are located at the upper or proximal extremity, which is near the torso. The femoral extremities are thickest in the lower extremity and thinnest in the higher extremity.

The neck is squeezed in the middle and measures 4 to 5 cm in length, with the lowest diameter from front to rear. It is around 150 degrees in a baby and, on average, drops to 120 degrees in old age. The head of the femur can be felt deep as a resistance profound (deep) for the femoral artery in thin individuals with the thigh laterally turned.

Both the bigger and minor trochanters may be found here. The femur’s most lateral noticeable part is the greater trochanter, which has an almost box-like form. It’s easy to feel the larger trochanter. The lowest portion of the femur neck extends in a cone form as the lesser trochanter.

The linea quadrata, also known as the quadrate line, is a faint ridge that occasionally appears down the back of the body, starting at the center of the intertrochanteric crest.

The quadrate tubercle is situated on the intertrochanteric crest, about where the upper one-third and lower two-thirds meet. The epiphyseal line runs straight through the quadrate tubercle, according to a brief anatomical research.

Body of Femur Bone

The linea aspera, a conspicuous longitudinal ridge that diverges proximally and distally as the medial and lateral ridges, strengthens it. It is somewhat arched, making it convex in front and concave behind. The shaft cannot be felt because of the thigh’s extensive musculature.

Its occurrence varies amongst ethnic groups, ranging from 17 to 72%, and it is often reported that females are more likely than men to have it.

Lower part

Although its transverse diameter is larger than its anteroposteriorly (front to back) diameter, it has a slightly cuboid shape. It is made up of two condyles, which are oblong protuberances.

The patellar surface is a smooth, shallow articular depression that separates the somewhat protruding condyles on the anterior side. They protrude significantly posteriorly, and between them is a deep indentation known as the femur’s intercondylar fossa. The condyles are not quite parallel to one another; the medial’s long axis travels rearward and medially, whereas the lateral’s is almost immediately anteroposterior. The anterior cruciate ligament of the knee joint is related to an impression on the higher and rear portions of its lateral wall, while the posterior cruciate ligament.

It has two convexities, the lateral of which is wider, more noticeable, and reaches higher than the medial, as well as a median groove that runs downhill to the intercondyloid fossa.

Development

The ectoderm and the underlying mesoderm interact to produce the femur from the limb buds; this process takes place approximately during the fourth week of development.

By the conclusion of the embryonic phase, endochondral ossification has started, and by the 12th week of development, all of the long bones of the limbs, including the femur, have main ossification centers.

Blood Supply

Once the artery has passed through the ilioinguinal ligament, it becomes the main branch of the external iliac artery. A branch of the femoral artery is the medial and lateral circumflex arteries. They supply the femoral head through important anastomotic connections, as does the obturator artery, a branch of the internal iliac artery. The deep femoral artery’s perforating branches provide blood to the femur’s shaft and distal region.

Function of Femur Bone

The femur is also the origin of several biarticular muscles, such as the gastrocnemius and plantaris muscles, which bridge two joints. There are a total of 23 distinct muscles that either attach to or arise from the femur. The thigh is shown in cross-section as having three distinct fascial compartments, each of which has muscles.

Embryology

Leg growth and development are induced by the limb bud’s apical ectodermal ridge. The femur develops from endochondral ossification, in which bone replaces hyaline cartilage models, and is derived from the lateral plate somatic mesoderm of the lower limb bud. There is no cartilage model for the intramembranous ossification process that creates articular cartilages and epiphyseal plates. It is the myotomic component of the somites that produces the femur muscles. The periosteum, which envelops the femur, provides nourishment via the nearby blood supply.

Clinical significance

Fractures

Particularly when osteoporosis is present, a femur fracture that affects the femoral head, femoral neck, or the shaft of the femur just below the lesser trochanter may be categorized as a hip fracture. A traction splint can be used to treat femur fractures in a pre-hospital environment.

Adolescent Hip Disorder

Overweight teenage boys are more likely to have slipped capital femoral epiphysis (SCFE), a hip condition affecting the femoral head. Although the reason is frequently idiopathic, radiation treatment, renal failure, and endocrine dysfunction have all been linked to SCFE. Although early treatment with a single screw through the growth plate has been demonstrated to prevent increasing slippage, preventative therapy for SCFE remains debatable.

The modified Dunn method entails fixing the femoral head with screws after removing a wedge of the femoral neck to rectify the deformity. With the modified Dunn surgery, avascular necrosis and persistent hip pain were frequent post-operative sequelae.

Vascular

When the blood flow to the femoral head is interrupted, an uncommon pediatric condition known as Legg-Calve-Perthes disease (LCP) results. Twin research indicates that environmental variables including low socioeconomic status increase the likelihood of LCP. Inguinal hernias, Down syndrome, and genitourinary disorders are among the congenital deformities linked to LCP. The child’s age and illness stage determine how they should be managed. LCP can be treated with braces, acupuncture, exercise, bisphosphonates, and hip arthroscopy.

Environmental

A typical malformation of the long bones is caused by rickets, which is an inability to mineralize bone. The main mechanism by which the growth plate calcifies and encourages the formation of long bones is endochondral ossification. However, rickets reduce or eliminate this process. Atypical phosphate metabolism, decreased sun exposure, and inadequate calcium or phosphate consumption are further factors.

• Injuries and Conditions
• Femoral fractures
• Femoral Stress fracture
• Patellofemoral pain syndrome
• Femoral Neck Fracture
• Greater Trochanteric Pain Syndrome