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Jai Ganesh

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Femur

Femur

Gist

The femur, or thigh bone, is the longest, strongest, and heaviest bone in the human body, extending from the hip to the knee. It is critical for weight-bearing, walking, and running. Key structures include the ball-shaped head (hip joint), a strong shaft, and the condyles (knee joint).

The femur, or thigh bone, is the body's longest, strongest, and heaviest bone, running from the hip to the knee, supporting body weight, and enabling leg movement for activities like walking, running, and jumping. It connects to the pelvis at the hip (forming the hip joint) and the tibia (shin bone) at the knee, acting as a crucial pillar and anchor point for powerful muscles. 

Summary:

What Is the Femur?

The femur is the longest, strongest, and heaviest bone in the human body, making it a difficult one to break. It’s also protected by various muscles and helps you maintain your posture and balance.

Femur bone function

Your femur connects many important muscles, tendons, and ligaments in your hips and knees to the other parts of your body, including parts of the circulatory system. More than that, it helps you carry your body weight when you stand and move. Your femur is critical in helping you maintain stability so you don’t fall over easily.

The femur also contains bone marrow, which is a soft, fatty tissue made up of stem cells. Stem cells have two unique abilities that make them essential to survival — they can make more stem cells, and they can “morph” or develop into other types of cells (this process is called “differentiation”).

These stem cells form two types of bone marrow: red and yellow. Each has an important job. Red bone marrow cells produce all the components of your blood (red and white blood cells and blood platelets). Yellow bone marrow cells store fat, which is needed for energy and to produce bone, cartilage, and muscles. From birth to around age 7, your bones contain only red marrow. From then on, yellow bone marrow gradually replaces red.

Details

The femur or thigh bone is the only bone in the thigh — the region of the lower limb between the hip and the knee. In many four-legged animals, the femur is the upper bone of the hindleg.

The top of the femur fits into a socket in the pelvis called the hip joint, and the bottom of the femur connects to the shinbone (tibia) and kneecap (patella) to form the knee. In humans the femur is the largest and thickest bone in the body.

Structure

The femur is the only bone in the upper leg and the longest bone in the human body. The two femurs converge medially toward the knees, where they articulate with the proximal ends of the tibiae. The angle at which the femora converge is an important factor in determining the femoral-tibial angle. In females, thicker pelvic bones cause the femora to converge more than in males.

In the condition genu valgum (knock knee), the femurs converge so much that the knees touch. The opposite condition, genu varum (bow-leggedness), occurs when the femurs diverge. In the general population without these conditions, the femoral-tibial angle is about 175 degrees.

The femur is the thickest bone in the human body. It is considered the strongest bone by some measures, though other studies suggest the temporal bone may be stronger. On average, the femur length accounts for 26.74% of a person's height, a ratio found in both men and women across most ethnic groups with minimal variation. This ratio is useful in anthropology, as it provides a reliable estimate of a person's height from an incomplete skeleton.

The femur is classified as a long bone, consisting of diaphysis (shaft or body) and two epiphyses (extremities) that articulate with the hip and knee bones.

Upper part

The upper or proximal extremity (close to the torso) contains the head, neck, the two trochanters and adjacent structures. The upper extremity is the thinnest femoral extremity, the lower extremity is the thickest femoral extremity.

The head of the femur, which articulates with the acetabulum of the pelvic bone, comprises two-thirds of a sphere. It has a small groove, or fovea, connected through the round ligament to the sides of the acetabular notch. The head of the femur is connected to the shaft through the neck or collum. The neck is 4–5 cm. long and the diameter is smallest front to back and compressed at its middle. The collum forms an angle with the shaft in about 130 degrees. This angle is highly variant. In the infant, it is about 150 degrees and in old age reduced to 120 degrees on average. An abnormal increase in the angle is known as coxa valga and an abnormal reduction is called coxa vara. Both the head and neck of the femur is vastly embedded in the hip musculature and can not be directly palpated. In skinny people with the thigh laterally rotated, the head of the femur can be felt deep as a resistance profound (deep) for the femoral artery.

The transition area between the head and neck is quite rough due to attachment of muscles and the hip joint capsule. Here the two trochanters, greater and lesser trochanter, are found. The greater trochanter is almost box-shaped and is the most lateral prominent of the femur. The highest point of the greater trochanter is located higher than the collum and reaches the midpoint of the hip joint. The greater trochanter can easily be felt. The trochanteric fossa is a deep depression bounded posteriorly by the intertrochanteric crest on the medial surface of the greater trochanter. The lesser trochanter is a cone-shaped extension of the lowest part of the femur neck. The two trochanters are joined by the intertrochanteric crest on the back side and by the intertrochanteric line on the front.

A slight ridge is sometimes seen commencing about the middle of the intertrochanteric crest, and reaching vertically downward for about 5 cm. along the back part of the body: it is called the linea quadrata (or quadrate line).

About the junction of the upper one-third and lower two-thirds on the intertrochanteric crest is the quadrate tubercle located. The size of the tubercle varies and it is not always located on the intertrochanteric crest and that also adjacent areas can be part of the quadrate tubercle, such as the posterior surface of the greater trochanter or the neck of the femur. In a small anatomical study it was shown that the epiphyseal line passes directly through the quadrate tubercle.

Body

The body of the femur (or shaft) is large, thick and almost cylindrical in form. It is a little broader above than in the center, broadest and somewhat flattened from before backward below. It is slightly arched, so as to be convex in front, and concave behind, where it is strengthened by a prominent longitudinal ridge, the linea aspera which diverges proximally and distal as the medial and lateral ridge. Proximally the lateral ridge of the linea aspera becomes the gluteal tuberosity while the medial ridge continues as the pectineal line. Besides the linea aspera the shaft has two other bordes; a lateral and medial border. These three bordes separate the shaft into three surfaces: One anterior, one medial and one lateral. Due to the vast musculature of the thigh the shaft can not be palpated.

The third trochanter is a bony projection occasionally present on the proximal femur near the superior border of the gluteal tuberosity. When present, it is oblong, rounded, or conical in shape and sometimes continuous with the gluteal ridge. A structure of minor importance in humans, the incidence of the third trochanter varies from 17–72% between ethnic groups and it is frequently reported as more common in females than in males.

Lower part

The lower extremity of the femur (or distal extremity) is the thickest femoral extremity, the upper extremity is the shortest femoral extremity. It is somewhat cuboid in form, but its transverse diameter is greater than its antero-posterior (front to back). It consists of two oblong eminences known as the condyles.

Anteriorly, the condyles are slightly prominent and are separated by a smooth shallow articular depression called the patellar surface. Posteriorly, they project considerably and a deep notch, the Intercondylar fossa of femur, is present between them. The lateral condyle is the more prominent and is the broader both in its antero-posterior and transverse diameters. The medial condyle is the longer and, when the femur is held with its body perpendicular, projects to a lower level. When, however, the femur is in its natural oblique position the lower surfaces of the two condyles lie practically in the same horizontal plane. The condyles are not quite parallel with one another; the long axis of the lateral is almost directly antero-posterior, but that of the medial runs backward and medialward. Their opposed surfaces are small, rough, and concave, and form the walls of the intercondyloid fossa. This fossa is limited above by a ridge, the intercondyloid line, and below by the central part of the posterior margin of the patellar surface. The posterior cruciate ligament of the knee joint is attached to the lower and front part of the medial wall of the fossa and the anterior cruciate ligament to an impression on the upper and back part of its lateral wall.

The articular surface of the lower end of the femur occupies the anterior, inferior, and posterior surfaces of the condyles. Its front part is named the patellar surface and articulates with the patella; it presents a median groove which extends downward to the intercondyloid fossa and two convexities, the lateral of which is broader, more prominent, and extends farther upward than the medial.

Each condyle is surmounted by an elevation, the epicondyle. The medial epicondyle is a large convex eminence to which the tibial collateral ligament of the knee-joint is attached. At its upper part is the adductor tubercle and behind it is a rough impression which gives origin to the medial head of the gastrocnemius. The lateral epicondyle which is smaller and less prominent than the medial, gives attachment to the fibular collateral ligament of the knee-joint.

Development

The femur develops from the limb buds as a result of interactions between the ectoderm and the underlying mesoderm; formation occurs roughly around the fourth week of development.

By the sixth week of development, the first hyaline cartilage model of the femur is formed by chondrocytes. Endochondral ossification begins by the end of the embryonic period and primary ossification centers are present in all long bones of the limbs, including the femur, by the 12th week of development. The hindlimb development lags behind forelimb development by 1–2 days.

Function

As the femur is the only bone in the thigh, it serves as an attachment point for all the muscles that exert their force over the hip and knee joints. Some biarticular muscles – which cross two joints, like the gastrocnemius and plantaris muscles – also originate from the femur. In all, 23 individual muscles either originate from or insert onto the femur.

In cross-section, the thigh is divided up into three separate fascial compartments divided by fascia, each containing muscles. These compartments use the femur as an axis, and are separated by tough connective tissue membranes (or septa). Each of these compartments has its own blood and nerve supply, and contains a different group of muscles. These compartments are named the anterior, medial and posterior fascial compartments.

Clinical significance:

Fractures

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. Femur fractures can be managed in a pre-hospital setting with the use of a traction splint.

Cortical desmoid

Cortical desmoid (also known as a tug lesion or periosteal desmoid) is an irregularity of the distal femoral cortex commonly observed is adolescents.

Additional Information

The femur is the longest, strongest bone in your body. It plays an important role in how you stand, move and keep your balance. Femurs usually only break from serious traumas like car accidents. But if your bones are weakened by osteoporosis, you have an increased risk for fractures you might not even know about.

Overview:

What is the femur?

The femur is your thigh bone. It’s the longest, strongest bone in your body. It’s a critical part of your ability to stand and move. Your femur also supports lots of important muscles, tendons, ligaments and parts of your circulatory system.

Because it’s so strong, it usually takes a severe trauma like a fall or car accident to break your femur. If you do experience a fracture, you’ll likely need surgery to repair your bone and physical therapy to help you regain your strength and ability to move.

Your femur, like all bones, can be affected by osteoporosis.

Function:

What does the femur do?

Your femur has several important jobs, including:

* Holding the weight of your body when you stand and move
* Stabilizing you as you move
* Connecting muscles, tendons and ligaments in your hips and knees to the rest of your body

Anatomy:

Where is the femur located?

The femur is the only bone in your thigh. It runs from your hip to your knee.

What does the femur look like?

The femur has two rounded ends and a long shaft in the middle. It’s the classic shape used for bones in cartoons: A cylinder with two round bumps at each end.

Even though it’s one long bone, your femur is made up of several parts. These include:

Femur proximal aspect

The upper (proximal) end of your femur connects to your hip joint. The proximal end (aspect) contains the:

* Head
* Neck
* Greater trochanter
* Lesser trochanter
* Intertrochanteric line and crest

Femur shaft

The shaft is the long portion of the femur that supports your weight and forms the structure of your thigh. It angles slightly toward the center of your body. The shaft of your femur includes the:

* Linea aspera
* Gluteal tuberosity
* Pectineal line
* Popliteal fossa

Femur distal aspect

The lower (distal) end of your femur forms the top of your knee joint. It meets your tibia (shin) and patella (kneecap). It includes the:

* Medial and lateral condyles
* Medial and lateral epicondyles
* Intercondylar fossa

All of these parts and labels are usually more for your healthcare provider to use as they describe where you’re having pain or issues. If you ever break your femur — a femoral fracture — your provider might use some of these terms to describe where your bone was damaged.

How big is the femur?

Your femur is the largest bone in your body. Most adult femurs are around 18 inches long.

The femur is also the strongest bone in your body. It can support as much as 30 times the weight of your body.

Conditions and Disorders:

What are the common conditions and disorders that affect the femur?

The most common issues that affect femurs are fractures, osteoporosis and patellofemoral pain syndrome.

Femur fractures

A bone fracture is the medical term for breaking a bone. Because femurs are so strong, they’re usually only broken by serious injuries like car accidents, falls or other traumas. Symptoms of a fracture include:

* Pain
* Swelling
* Tenderness
* Inability to move your leg like you usually can
* Bruising or discoloration
* A deformity or bump that’s not usually on your body

Go to the emergency room right away if you’ve experienced a trauma or think you have a fracture.

Osteoporosis

Osteoporosis weakens bones, making them more susceptible to sudden and unexpected fractures. Many people don’t know they have osteoporosis until after it causes them to break a bone. There usually aren’t obvious symptoms.

Females and adults older than 50 have an increased risk of developing osteoporosis. Talk to your provider about a bone density screening that can catch osteoporosis before it causes a fracture.

Patellofemoral pain syndrome

Patellofemoral pain syndrome (PFPS) is pain around and under your kneecap (patella). It’s sometimes called runner’s or jumper’s knee. PFPS can be caused by everything from overusing your knees to getting new shoes. Symptoms of PFPS include:

* Pain while bending your knee, including squatting or climbing stairs
* Pain after sitting with your knees bent
* Crackling or popping sounds in your knee when standing up or climbing stairs
* Pain that increases with changes to your usual playing surface, sports equipment or activity intensity

Talk to your provider if you’re experiencing new pain in your knee.

What tests are done on femurs?

The most common test done to check the health of your femur is a bone density test. It’s sometimes called a DEXA or DXA scan. A bone density test measures how strong your bones are with low levels of X-rays. It’s a way to measure bone loss as you age.

If you’ve experienced a femoral fracture your provider or surgeon might need imaging tests, including:

* X-rays
* Magnetic resonance imaging (MRI)
* CT scan

What are common treatments for femurs?

Usually, your femur won’t need treatment unless you’ve experienced a fracture or have been diagnosed with osteoporosis.

Femur fracture treatment

How your fracture is treated depends on which type it is and what caused it. You’ll need some form of immobilization, like a splint or cast, and will probably need surgery to realign (set) your bone to its correct position and secure it in place so it can heal.

Osteoporosis treatment

Treatments for osteoporosis can include exercise, vitamin and mineral supplements and medications.

Exercise and taking supplements are usually all you’ll need to prevent osteoporosis. Your provider will help you develop a treatment plan that’s customized for you and your bone health.

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