Femur Anatomy: Complete Guide with Parts, Names, Functions & Diagram

Overview of Femur Anatomy

The femur, or thigh bone, is the main bone in your thigh. It connects your hip to your knee and is the largest and strongest bone in your body. In animals with four legs, it is the upper bone in the back leg. The femur anatomy has several parts: the shaft, head, neck, and more. The top part fits into your hip joint, and the bottom part connects to your shinbone (tibia) and kneecap (patella) to form your knee. Humans have two femurs, one in each leg, and they meet at the knees, connecting to the tibiae. The angle where they meet affects the angle of your knees. The femur is about 26.74% of a person’s height, so it can help estimate the height of someone from their skeleton.

In this article, we will see the detailed anatomy of the femur with its parts, names, functions & diagrams. It will help us to understand more about the human body parts.

Femur Anatomy Diagram

Femur Bone Anatomy, Parts, Names & Diagram

Parts of Femur

  • Femoral Head
  • Femoral Neck
  • Femur Shaft
  • Medial & Lateral Condyle
  • Intercondylar Fossa/ Notch
  • Epicondyle
  • Patellar Surface & Groove
  • Linea Aspera

Femur Anatomy

Femoral Head

The femoral head is the rounded top part of the thigh bone (femur). It connects to the femoral neck and fits into the acetabulum of the pelvis, forming the hip joint.

The femoral head is shaped like a ball and has a small pit called the fovea capitis femoris, where a ligament attaches. This area is important because it can suffer from a condition called avascular necrosis, especially after hip injuries.

The femoral head acts as the “ball” in the hip joint, allowing a wide range of motion. It is covered with smooth cartilage, which helps it move easily against the acetabulum. 

Inside the femoral head, there are different patterns of trabeculae (small, beam-like structures within the bone):

  1. Primary Compressive Group: These trabeculae run vertically from the top of the femoral head to the inner neck, bearing the main load.
  2. Primary Tensile Group: These run from the bottom of the femoral head to the outer side of the femur, handling tensile (stretching) forces.
  3. Secondary Compressive Group: These follow additional lines of stress within the upper femur.
  4. Secondary Tensile Group: These align with tensile forces in the outer upper femur.
  5. Greater Trochanteric Group: These follow stress lines within the greater trochanter, a bony prominence on the femur.

There is an area with fewer trabeculae called Ward’s triangle, which is a weak spot in the bone. This is different from Babcock’s triangle, a region seen on X-rays where hip tuberculosis often occurs.

Femoral Neck

The femoral neck is a connecting bone structure between the femoral head and shaft. It is shaped like a flattened pyramid, with a wider angle outward.

The neck is flat from front to back, narrower in the middle, and wider on the outer side compared to the inner side.

The lateral half of the neck has a larger vertical diameter due to its sloping lower edge. It joins the body near the lesser trochanter. This side measures about one-third more than its front-to-back diameter. The medial half is smaller and more circular.

The front of the neck has many small holes for blood vessels. There are slight grooves along the top front where the hip joint capsule fibers sit.

The back of the neck is smooth, broader, and more concave than the front. The hip joint capsule attaches about 1 cm above the intertrochanteric crest.

The top border is short and thick. It ends at the greater trochanter and has large holes for vessels. The bottom border is longer and narrower. It curves slightly backward to reach the lesser trochanter.

Femur Shaft

The femur, or your thigh bone, angles slightly inward and brings your knees closer to your body center to maintain balance.

On the backside of the femur, there are rough ridges called the rough line or linea aspera. These ridges split below into two lines, medial and lateral supracondylar lines, with a flat area(popliteal surface) in between.

Near the top, the rough line becomes the pectineal line on the inside and the rough gluteal tuberosity on the outside, where your gluteus maximus muscle attaches.

Towards the bottom, the linea aspera widens and becomes the part of popliteal fossa. The medial and lateral borders become the medial and lateral supracondylar lines. The medial supracondylar line ends at the adductor tubercle, where the adductor magnus muscle attaches.

Medial & Lateral Condyle

The lower end of the femur has two projections: the medial and lateral condyles. The medial condyle is bigger because it bears more weight since the body’s center leans toward the inner side of the knee.

On the back of the medial condyle, a ridge splits into two parts: the medial and lateral supracondylar ridges.

The most distant ridge on the inner side of the medial condyle is called the “medial epicondyle,” which you can feel by running your fingers from the patella inward when the knee is bent. The extra part of the medial femoral condyle helps the knee rotate passively.

The lateral condyle is the other ridge on the femur’s lower end. It is more prominent and wider from front to back and side to side compared to the medial condyle.

Intercondylar Fossa/ Notch

The intercondylar fossa of the femur is like a deep groove between two bumps at the bottom of your thigh bone. These bumps are called the medial and lateral epicondyles.

They are the parts that connect to your knee. On the front side of your thigh bone, the bumps are smoother and not pronounced. There is a flat area called the patellar surface where your kneecap fits.

You might also hear these areas called the patellar groove, patellar sulcus, or trochlear groove of the femur. They are all different ways of talking about the same parts of your knee joint.

Epicondyle

The medial epicondyle of the femur is a bony protrusion on the inner side of the thigh bone’s lower end. It is above the medial condyle and has a bump called the adductor tubercle.

It is the portion where muscles attach. This bump separates thigh muscles into groups. Behind it, there is a rough area where a calf muscle attaches. The lateral epicondyle is smaller and less noticeable.

It connects to a ligament in the knee. Below it, there is a groove that curves upward and backward on the back end of the bone.

Patellar Surface & Groove

The patellar surface of the femur is a groove-like area at the lower front part of the thigh bone. This groove is between the inner and outer parts of the lower femur.

It connects with a ridge on the patella (kneecap), forming the patellofemoral joint. This joint allows the kneecap to smoothly slide over the end of the thigh bone when we bend or straighten our knee.

Linea Aspera

The linea aspera is a prominent bony ridge located on the posterior side of the femur, or thigh bone. This structure plays a crucial role as an attachment site for various muscles and connective tissues, effectively dividing the thigh into three distinct compartments.

The linea aspera features two primary edges known as the medial and lateral lips, with a roughened area in between.

It provides critical attachment points for the adductor muscles, which are responsible for moving the leg towards the midline of the body. The intermuscular septa are connective tissues that separate different groups of thigh muscles.

The distinctive ridges of the linea aspera are formed by the mechanical pull of the attached muscles, gradually shaping the bone over time.

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External Sources-

  • Wikipedia
  • KenHub
  • Optometrists
  • Cleveland Clinic
  • American Academy of Ophthalmology

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