Last Updated on June 8, 2025
The femur, or thigh bone, is the longest and strongest bone in the human body. It plays a central role in supporting body weight, enabling locomotion, and transmitting forces between the pelvis and lower limb.
Anatomically, the femur is divided into three main parts: the upper end, shaft, and lower end. Its structure and multiple muscular attachments make it a key element in movement and weight bearing.
The upper end bears a rounded head, whereas the lower end is widely expanded to form two large condyles. The head is directed medially. The cylindrical shaft is convex forward.
Upper end of Femur Bone
The upper end of the femur includes the head, the neck, the greater trochanter, the lesser trochanter, the intertrochanteric line, and the intertrochanteric crest.
Head of Femur
The head articulates with the acetabulum to form a hip joint. It is more than half a sphere and is directed medially, upwards, and slightly forwards.
The fovea is a roughened pit just below and behind the center of the head and is the site where the ligament of the head of the femur (ligamentum teres) attaches. The ligament is also accompanied by a small artery.
Most of the surface of the head is covered by cartilage.
Neck of Femur
The neck is about is about 3-3.5 cms long and connects head with the shaft. The neck forms an angle with the shaft, known as the neck-shaft angle, and is about 125 in adults [lesser in females]. The angle facilitates movements of the hip joint. The femoral neck is strengthened by a thickening of bone called the calcar femorale present along its concavity.
The neck has two borders and two surfaces
The upper border, concave and horizontal, meets the shaft at the greater trochanter. The lower border, straight and oblique, meets the shaft near the lesser trochanter.
The anterior surface is flat and meets the shaft at the intertrochanteric line. The anterior surface of the femoral neck is entirely intracapsular. The upper part of this surface may be covered by articular cartilage.
The posterior surface of the neck is convex from above downwards and concave from side to side. It meets the shaft at the intertrochanteric crest. It is not intracapsular in its lower lateral part.
Anteversion
Anteversion is the angle formed between the transverse axis of the head and neck of the femur and the lower ends of the femur. It is about 15 degrees.
Femoral anteversion is important as it leads to in-toeing and other issues when it is in excess. It has been discussed in separate article.
Read- What is femoral anteversion
Greater Trochanter
The greater trochanter is a large quadrangular prominence located at the upper part of the junction of the neck with the shaft. The upper border of the trochanter lies at the level of the center of the head.
The greater trochanter has an upper border with an apex, and 3 surfaces (anterior, medial and lateral). The apex is the inturned posterior part of the posterior border. The anterior surface is rough in its lateral part. The medial surface presents a rough impression, above and a deep trochanteric fossa, below. The lateral surface is crossed by an oblique ridge directed downwards and forwards.
Lesser Trochanter
It is a conical eminence directed medially and backwards from the junction of the posterior part of the neck with the shaft.
Intertrochanteric Line
It marks the junction of the neck with the femur. It is a roughened ridge from the anterosuperior angle of the greater trochanter (as a tubercle) and is continuous below with the spiral line in front of the lesser trochanter.
The spiral line is a curved line with its superior end adjacent to the lesser trochanter, nearly continuous with the intertrochanteric line, and converging inferiorly with the pectineal line to form the medial lip of the linea aspera.
It forms the medial boundary of the distal attachment of the iliacus muscle. The spiral line winds around the shaft below the lesser trochanter to reach the posterior surface of the shaft.
Intertrochanteric Crest
It marks the junction of the posterior surface of the neck with the shaft of the femur. It is a smooth rounded ridge which begins above at the posterior superior angle of the greater trochanter and ends at the lesser trochanter. The rounded elevation, a little above its middle is called the quadrate tubercle.
Shaft of Femur
The shaft is almost a cylindrical structure, wide superiorly and inferiorly, and narrowest in the middle. It is convex forwards and is directed obliquely downwards and medially.
Surfaces and Borders
The femoral shaft has three surfaces and three borders:
Surfaces:
- Anterior surface – Faces forward and is smooth.
- Medial surface – Faces medially between the medial and posterior borders.
- Lateral surface – Faces laterally between the lateral and posterior borders.
Borders:
The medial and lateral borders are rounded and ill-defined, but the posterior border is in the form of a broad, roughened ridge, called the linea aspera.
- Medial border
- Lateral border
- Posterior border – Marked by the prominent linea aspera, a rough longitudinal ridge.
Linea Aspera
The linea aspera is a major anatomical landmark, serving as the site for several muscle attachments:
- Lateral lip – Origin of vastus lateralis
- Medial lip – Origin of vastus medialis
- Intermediate area – Insertion of adductors (adductor longus, brevis, magnus)
It splits distally into the medial and lateral supracondylar lines, leading to the respective femoral condyles.
Linea aspera is an important landmark in orthopedic surgeries involving the reduction of femoral fractures.
The Linea aspera has distinct medial and lateral lips. The medial and lateral surfaces are directed more backwards than to the sides.
Pectineal Line or Spiral Line and Gluteal Tuberosity
In upper one-third of the shaft, the two lips of the Linea aspera diverge widely to form an additional posterior surface and
- 4 borders: medial, lateral, spiral line and the lateral lip of the gluteal tuberosity)
- 4 surfaces: (anterior, medial, lateral and posterior).
The gluteal tuberosity is a broad, roughened ridge on the lateral part of the posterior surface.
Popliteal Surface
Similarly, the two lips of the Linea aspera diverge in the lower one-third and enclose an additional, popliteal surface. Thus, this part of the shaft has
- 4 borders – medial, lateral, medial supracondylar line, and lateral supracondylar line
- 4 surfaces- anterior, medial, lateral, and popliteal.
The medial border and medial supracondylar line meet inferiorly to obliterate the medial surface.
Nutrient Foramen
A large nutrient foramen is located along the linea aspera, typically directed away from the knee (nutrients generally are directed away from the growing end). It transmits the nutrient artery, which is a branch of the second perforating artery of the profunda femoris.
Lower End of Femur
The lower end of the femur is broad, expanded, and forms the proximal half of the knee joint. It consists of:
Medial and Lateral Condyles
The lower end of the femur has two large condyles – medial and lateral. Anteriorly, the two condyles are united and are in a line with the front of the shaft. Posteriorly, they are separated by a deep gap, termed the intercondylar fossa or intercondylar notch, and project backwards much beyond the plane of the popliteal surface.
Lateral Condyle
The lateral condyle is flat laterally, less prominent than the medial condyle, and is stouter. The lateral condyle is more prominent anteriorly.
The lateral condyle has a prominence called the lateral epicondyle. It provides attachment to the fibular (lateral) collateral ligament.
Below it lies the popliteal groove with a deeper anterior part and a shallower posterior part. The popliteal groove allows for the passage of the popliteal tendon.
Medial Condyle
It is larger and projects more distally. The medial condyle is convex medially. It also bears a prominent point called the medial epicondyle. It lies above the medial condyle and gives attachment to the tibial (medial) collateral ligament.
The adductor tubercle is a projection posterosuperior to the medial epicondyle. It serves as an important anatomical and surgical landmark. It also provides attachment to the adductor magnus, the hamstring part. The epiphyseal line for the lower end of the femur passes through it.
Articular Surface
The two condyles are partially covered by a large articular surface. Anteriorly, the condyles articulate with the patella, and this articulation extends more on the lateral condyle than on the medial.
Between the two condyles, the surface is grooved vertically.
Two faint grooves separate the patellar articulation surface from the tibial articulation surfaces. Tibial articulation surface over the lateral condyle is short and straight anteroposterior, whereas the part over the medial condyle is longer and is convex medially.
Intercondylar Fossa or Notch
The intercondylar fossa or notch separates the lower and posterior parts of the two condyles. The intercondylar line separates the notch from the popliteal surface. Anteriorly, the notch is limited by the patellar articular surface.
It is an important site for attachment of the cruciate ligaments, ACL and PCL.
Attachments on the Femur
Head of Femur
The fovea on the head of the femur provides attachment to the ligament of the head (round ligament, or ligamentum teres).
Greater Trochanter
- The piriformis is inserted into the apex
- The gluteus minimus is inserted into the rough lateral part of the anterior surface
- The obturator internus and the two gemelli are inserted into the upper rough impression on the medial surface
- The obturator externus is inserted into the trochanteric fossa
- The gluteus medius is inserted into the ridge on the lateral surface.
- The trochanteric bursa of the gluteus medius lies in front of the trochanteric ridge, and the trochanteric bursa of the gluteus maximus lies behind the ridge.
Lesser Trochanter
- Iliopsoas
- The psoas major is inserted on the apex and medial part of the rough anterior surface.
- The iliacus is inserted on the anterior surface of the base of the trochanter and on the area below.
- Gluteus minimus bursa lies deep to the upper horizontal fibers of the adductor magnus.
Intertrochanteric Line
The following structures attach to the intertrochanteric line
- Capsular ligament of the hip joint
- Iliofemoral ligament in its upper part
- The lower band of the iliofemoral ligament in its lower part
- The highest fibers of the vastus lateralis from the upper end
- The highest fibers of the vastus medialis from the lower end
- Quadratus femoris is attached to the quadrate tubercle
Shaft of the Femur
- The medial and popliteal surfaces are bare [ Except for part of the gastrocnemius origin on the popliteal surface]
- Vastus intermedius – upper three-fourths of the anterior and lateral surfaces.
- Articularis genu – just below the vastus intermedius.
- Vastus lateralis – upper part of the intertrochanteric line, anterior and inferior borders of the greater trochanter, the lateral lip of the gluteal tuberosity, and the upper half of the lateral lip of the line aspera.
- Vastus medialis – Lower part of the intertrochanteric line, the spiral line, the medial lip of the linea aspera, and the upper one–fourth of the medial supracondylar line.
- The gluteal tuberosity receives the insertion of the deeper fibers of the lower half of the gluteus maximus
- Adductor longus – Medial lip of the linea aspera between the vastus medialis and the adductor brevis and magnus
- Adductor brevis is inserted into a line extending from the lesser trochanter to the upper part of the linea aspera, behind the pectineus and the upper part of the adductor longus.
- Adductor magnus is inserted into the medial margin of the gluteal tuberosity, the linea aspera, the medial supracondylar line, and the adductor tubercle
- Pectineus is inserted on a line extending from the lesser trochanter to the linea aspera.
- The short head of the biceps femoris arises from the lateral lip of the linea aspera between the vastus lateralis and the adductor magnus, and from the upper two – thirds of the lateral supracondylar line
- Medial and lateral intermuscular septa are attached to the lips of the linea aspera and to the supracondylar line. These septae separate the extensor muscles from the adductor medially, and from the flexors laterally.
- The lower end of the lateral supracondylar line gives origin to the plantaris above and the upper part of the lateral head of the gastrocnemius below.
- The popliteal surface is covered with fat and forms the floor of the popliteal fossa. Medial head of the gastrocnemius extends to the popliteal surface just above the medial condyle.
Lateral Condyle
- The fibular collateral ligament of the knee attaches to the lateral epicondyle.
- The popliteus arises from the deep anterior part of the popliteal groove. When the knee is flexed, the tendon of this muscle lies in the shallow posterior part of the groove.
- The muscular impression near the lateral epicondyle gives origin to the lateral head of the gastrocnemius.
Medial Condyle
- Tibial collateral ligament of the knee – medial epicondyle
- Hamstring part of the adductor magnus attaches to the adductor tubercle
Intercondylar Notch
- Anterior cruciate ligament – posterior part of the medial surface of the lateral condyle.
- The intercondylar line provides attachment to the capsular ligament and laterally to the oblique popliteal ligament.
- The infrapatellar synovial fold is attached to the anterior border of the intercondylar fossa.
Blood supply of the Femur
The femur receives a rich blood supply from multiple sources, which are crucial for both bone health and healing, especially in fracture management.
Nutrient Artery
- Arises from the second perforating branch of the profunda femoris artery.
- Enters through the nutrient foramen on the posterior aspect of the shaft, directed upward.
- Supplies the medullary cavity and inner two-thirds of the cortex.
Metaphyseal and Epiphyseal Arteries
The smaller, medial part of the head, near the fovea, is supplied by medial epiphyseal arteries derived from the posterior division of the obturator artery and from the ascending branch of the medial circumflex femoral artery.
These arterial twigs enter the acetabular notch and then pass along the round ligament to reach the head.
The larger, lateral part of the head is supplied by lateral epiphyseal arteries which are derived from the retinacular branches of the medial circumflex femoral artery.
This set constitutes the main supply and damage to it results in necrosis of the head of the following fractures of the neck of the femur. After epiphyseal fusion, the lateral epiphyseal arteries anastomose freely with the metaphyseal arteries.
Retinacular Arteries (Ascending Cervical Branches)
The intracapsular neck is supplied by the retinacular arteries derived chiefly from the trochanteric anastomosis. The vessels produce longitudinal grooves and foramina directed towards the head, mainly on the anterior and posterior-superior surface.
The ascending branch of the medial circumflex femoral artery supplies the extracapsular part of the neck.These vessels are vulnerable in femoral neck fractures, leading to risk of avascular necrosis (AVN) of the femoral head.
Artery to the Ligament of the Head of the Femur
- A small vessel from the obturator artery.
- Enters through the fovea capitis.
- Limited contribution in adults but important in children before other sources mature.
Genicular Arteries
The lower end is supplied by genicular arteries and anastomosis around the knee
Clinical Significance of Femur
The femur plays a central role in orthopedic and trauma cases. Its anatomical and biomechanical features make it vulnerable to specific injuries and diseases.
Fractures
- Femoral neck fractures are common in the elderly due to osteoporosis and often result in disrupted blood supply and risk of avascular necrosis.
- Intertrochanteric fractures are more stable but occur frequently in older adults following a fall.
- Femoral shaft fractures result from high-energy trauma (e.g., road traffic accidents) and require intramedullary nailing or external fixation.
- Distal femur fractures can involve the knee joint and may extend intra-articularly, affecting joint function.
Hip Joint Disorders
The femoral head forms the hip joint with the acetabulum. Any pathology involving the femoral head (e.g., Perthes disease, slipped capital femoral epiphysis) significantly affects gait and development in children.
Joint arthritis may result from osteoarthritis, rheumatoid arthritis of infection, which can affect any age.
Disruption of blood flow (especially via retinacular arteries) after trauma can lead to death of bone tissue in the femoral head, a serious complication in intracapsular fractures.
Bone Tumors
- The femur is a common site for primary bone tumors such as:
- Osteosarcoma (typically metaphyseal)
- Ewing sarcoma
- Metastases from breast, prostate, and lung
Landmarks in Surgery and Imaging
- The greater trochanter is used as a key landmark in intramuscular injections, hip surgeries, and imaging orientation.
- Ossification of the lower end of the femur is of medicolegal importance. Presence of its center in a newly born child found dead indicates that the child was capable of independent existence.
- Coxa valga is a condition where the femoral neck-shaft angle is more than normal. ( 135 degrees)
- Coxa vara is a condition where the neck-shaft angle is less than normal (120 degrees)
Sources
A list of key peer-reviewed studies, textbooks, and clinical references used in preparing this article is provided below for transparency and professional context.
- Netter, F. H. (2014). Atlas of Human Anatomy (6th ed.). Saunders Elsevier.
- Standring, S. (2015). Gray’s Anatomy: The Anatomical Basis of Clinical Practice (41st ed.). Elsevier Health Sciences.
- Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2013). Clinically Oriented Anatomy (7th ed.). Lippincott Williams & Wilkins.
- Chang A, Breeland G, Black AC, et al. Anatomy, Bony Pelvis and Lower Limb: Femur. [Updated 2023 Nov 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532982
