Pelvis & lower limb · Thigh
Femur
The femur is the single bone of the thigh. Its head fits the acetabulum of the hip bone at the hip joint, and its distal condyles articulate with the tibia and the patella at the knee joint.
- Latin (TA)
- Femur
- Type
- Long bone: a tubular shaft
- Side
- Paired — right and left
- Model size
- 45.4 cm longest
Showing a right bone. Rotate it to inspect every surface; switch sides to practise siding.
3D model: Z-Anatomy (CC BY-SA 4.0), derived from BodyParts3D © DBCLS (CC BY-SA 2.1 JP). Adapted by PharmaWallah. Credits & licence
Landmarks
25 of 26 marked on the modelTap a landmark to find it on the bone and read what it is.
The smooth, rounded articular upper end of the femur, about two-thirds of a sphere.
Where: At the upper end, directed upwards, medially and slightly forwards.
Why it matters: Fits the acetabulum at the hip joint; its direction (medial) is the first step in siding the bone.
Related: Hip joint.
Marked on the model at the point Z-Anatomy places this label.
A small pit on the head, not covered by articular cartilage.
Where: Just below and behind the centre of the femoral head.
Why it matters: Attachment of the ligament of the head of the femur, which carries a small artery to the head.
Related: Ligament of the head of the femur.
Marked on the model at the point Z-Anatomy places this label.
The narrow bar of bone joining the head to the shaft.
Where: Between the head and the trochanters, directed upwards and medially from the shaft at an angle.
Why it matters: A common fracture site in older people; the retinacular arteries supplying the head run along it, so displaced fractures can cut off the head's blood supply.
Viva: Why can a displaced fracture of the femoral neck lead to avascular necrosis of the head?
Marked on the model at the point Z-Anatomy places this label.
A large, quadrilateral projection at the junction of the neck and shaft.
Where: At the upper lateral part of the femur; palpable on the side of the hip.
Why it matters: Insertion of the gluteus medius and minimus and of several short lateral rotators of the hip.
Related: Gluteus medius, gluteus minimus, piriformis, obturator internus and gemelli.
Viva: Which muscles insert into the greater trochanter?
Marked on the model at the point Z-Anatomy places this label.
A conical projection from the shaft below the neck.
Where: At the posteromedial part of the junction of neck and shaft.
Why it matters: Insertion of iliopsoas, the main flexor of the hip; its posteromedial position confirms orientation.
Related: Iliopsoas (psoas major and iliacus).
Marked on the model at the point Z-Anatomy places this label.
A rough ridge on the front of the bone where the neck joins the shaft.
Where: Anteriorly, running from the greater trochanter down and medially towards the lesser trochanter.
Why it matters: Marks the anterior attachment of the hip joint capsule and of the iliofemoral ligament.
Related: Hip joint capsule, iliofemoral ligament.
Marked on the model at the point Z-Anatomy places this label.
A prominent smooth ridge on the back of the bone joining the two trochanters.
Where: Posteriorly, from the greater trochanter down to the lesser trochanter.
Why it matters: Marks the posterior junction of neck and shaft; the hip capsule does not reach it behind, so part of the neck is outside the capsule posteriorly.
Marked on the model at the point Z-Anatomy places this label.
The long, cylindrical middle part of the bone, gently bowed forwards.
Where: Between the trochanters above and the condyles below.
Why it matters: Surrounded by the thigh muscles; vastus intermedius arises from its front and lateral surfaces.
Marked on the model at the point Z-Anatomy places this label.
A rough, raised ridge with medial and lateral lips down the back of the shaft.
Where: On the posterior surface of the middle part of the shaft.
Why it matters: Attachment of the adductors and the short head of biceps femoris, and origin of vastus medialis and lateralis; it faces backwards, which is used to side the bone.
Related: Adductor longus, brevis and magnus; short head of biceps femoris; vastus medialis and lateralis.
Viva: On which surface of the femur is the linea aspera?
Marked on the model at the point Z-Anatomy places this label.
A broad, rough ridge running up from the lateral lip of the linea aspera.
Where: On the upper posterolateral part of the shaft, below the greater trochanter.
Why it matters: Insertion of the deep part of gluteus maximus.
Related: Gluteus maximus.
Marked on the model at the point Z-Anatomy places this label.
A flat triangular area on the back of the lower shaft.
Where: Between the medial and lateral supracondylar lines, above the intercondylar fossa.
Why it matters: Forms the upper part of the floor of the popliteal fossa; the popliteal artery lies against it.
Marked on the model at the point Z-Anatomy places this label.
A small projection at the lower end of the medial supracondylar line.
Where: On the upper part of the medial condyle, above the medial epicondyle.
Why it matters: Insertion of the hamstring (ischial) part of adductor magnus.
Related: Adductor magnus.
Marked on the model at the point Z-Anatomy places this label.
The medial of the two large rounded masses at the lower end.
Where: At the lower end, on the medial side.
Why it matters: Articulates with the medial condyle of the tibia (through the medial meniscus) at the knee.
Related: Knee joint; posterior cruciate ligament on its lateral (intercondylar) surface.
Marked on the model at the point Z-Anatomy places this label.
The lateral of the two large rounded masses at the lower end.
Where: At the lower end, on the lateral side.
Why it matters: Articulates with the lateral condyle of the tibia at the knee; its lateral lip of the patellar surface is the more prominent one, which resists lateral displacement of the patella.
Related: Knee joint; anterior cruciate ligament on its medial (intercondylar) surface.
Marked on the model at the point Z-Anatomy places this label.
The most prominent point on the medial surface of the medial condyle.
Where: On the medial side of the medial condyle, below the adductor tubercle.
Why it matters: Attachment of the tibial (medial) collateral ligament of the knee.
Marked on the model at the point Z-Anatomy places this label.
The most prominent point on the lateral surface of the lateral condyle.
Where: On the lateral side of the lateral condyle.
Why it matters: Attachment of the fibular (lateral) collateral ligament of the knee.
Marked on the model at the point Z-Anatomy places this label.
A deep notch between the two condyles.
Where: At the back and underside of the lower end, between the condyles.
Why it matters: Houses the cruciate ligaments; it lies posteriorly, which confirms orientation.
Related: Anterior and posterior cruciate ligaments.
Viva: Where on the femur does the anterior cruciate ligament attach?
Marked on the model at the point Z-Anatomy places this label.
A smooth, grooved articular surface on the front of the lower end.
Where: Anteriorly, joining the two condyles in front.
Why it matters: Articulates with the posterior surface of the patella (the patellofemoral part of the knee joint).
Related: Patella.
Marked on the model at the point Z-Anatomy places this label.
Classification & region
Long bone: a tubular shaft (body) with two expanded ends, each ossifying from its own centres. It is the longest and strongest bone in the body.
- Proximal end
- The rounded head, the neck, and the greater and lesser trochanters, joined in front by the intertrochanteric line and behind by the intertrochanteric crest.
- Shaft (body)
- Smooth and rounded in front, with a raised ridge, the linea aspera, behind. The shaft slopes downwards and medially so the knees lie close to the midline.
- Distal end
- Two large condyles (medial and lateral) with their epicondyles, separated behind by the intercondylar fossa and joined in front by the patellar surface.
Hold it in the anatomical position
- Put the rounded head at the top, pointing medially (towards the midline).
- Turn the linea aspera (the rough ridge down the shaft) to face posteriorly.
- The condyles are at the bottom, with the deep intercondylar fossa behind and the smooth patellar surface in front.
- In the anatomical position the shaft is oblique, so its lower end lies closer to the midline than its upper end and both condyles rest on the same horizontal level.
Right or left? Side determination
- Identify the upper end: the rounded head on its neck.
- Turn the head to point medially.
- Turn the bone so the linea aspera faces backwards, towards you, as if the bone were in your own thigh (the intercondylar fossa is then at the back of the lower end, nearest you).
- Check: the lesser trochanter now projects backwards and medially, below the neck.
- The head points towards the midline, so the bone belongs to the opposite side: held this way, a head pointing to your left means a right femur.
Check yourself: switch the 3D model to “Left bone” and apply the same steps.
Articulations
- With the hip bone (acetabulum) at the Hip joint — Head of the femur.
- With the tibia at the Knee joint (tibiofemoral part) — Medial and lateral condyles.
- With the patella at the Knee joint (patellofemoral part) — Patellar surface.
Muscle and ligament attachments
| Structure | Type | Where on the bone |
|---|---|---|
| Gluteus medius | insertion | Lateral surface of the greater trochanter |
| Gluteus minimus | insertion | Anterior surface of the greater trochanter |
| Piriformis | insertion | Upper border of the greater trochanter |
| Obturator internus and the gemelli | insertion | Medial surface of the greater trochanter |
| Obturator externus | insertion | Trochanteric fossa |
| Quadratus femoris | insertion | Quadrate tubercle on the intertrochanteric crest |
| Iliopsoas | insertion | Lesser trochanter |
| Gluteus maximus (deep part) | insertion | Gluteal tuberosity |
| Pectineus | insertion | Pectineal line |
| Adductor longus, adductor brevis and adductor magnus (adductor part) | insertion | Linea aspera and the lines continuing from it |
| Adductor magnus (hamstring part) | insertion | Adductor tubercle |
| Vastus lateralis | origin | Greater trochanter region and the lateral lip of the linea aspera |
| Vastus medialis | origin | Intertrochanteric line, spiral line and medial lip of the linea aspera |
| Vastus intermedius | origin | Anterior and lateral surfaces of the shaft |
| Biceps femoris (short head) | origin | Lateral lip of the linea aspera |
| Gastrocnemius (medial head) | origin | Popliteal surface above the medial condyle |
| Gastrocnemius (lateral head) | origin | Lateral surface of the lateral condyle |
| Plantaris | origin | Lower end of the lateral supracondylar line |
| Popliteus | origin | Lateral surface of the lateral condyle (groove for popliteus) |
| Hip joint capsule | ligament | Intertrochanteric line in front; on the back of the neck behind, short of the intertrochanteric crest |
| Iliofemoral ligament | ligament | Intertrochanteric line |
| Ligament of the head of the femur | ligament | Fovea of the head |
| Anterior cruciate ligament | ligament | Medial surface of the lateral condyle (intercondylar fossa) |
| Posterior cruciate ligament | ligament | Lateral surface of the medial condyle (intercondylar fossa) |
| Tibial collateral ligament | ligament | Medial epicondyle |
| Fibular collateral ligament | ligament | Lateral epicondyle |
Functions
- Transmits body weight from the hip bone to the tibia in standing and walking.
- Acts as a long lever for the muscles that move the hip and knee.
- Gives attachment to the muscles of the gluteal region, thigh and calf.
- Its marrow cavity contains bone marrow (red marrow persists in the upper end in adults).
Clinical & practical relevance
- Fracture of the femoral neck is common in older people with osteoporosis, often after a minor fall; the limb is typically shortened and laterally rotated.
- The head is supplied mainly by retinacular branches of the medial circumflex femoral artery that run along the neck; a displaced intracapsular neck fracture can tear them and cause avascular necrosis of the head. The artery in the ligament of the head is usually small.
- Intertrochanteric fractures lie outside the capsule, so the head's blood supply is usually preserved.
- Fractures of the shaft need great force and can bleed heavily into the thigh.
- Fractures just above the condyles can be pulled backwards by gastrocnemius and endanger the popliteal artery that lies against the popliteal surface.
Identification tips
- Three quick checks: head medial, linea aspera posterior, intercondylar fossa posterior.
- The lesser trochanter points backwards and medially; if it points forwards, the bone is upside down or reversed.
- Intertrochanteric LINE is in front (Line = Leading); the CREST is behind.
- For the cruciates on the femur, the ACL goes to the LATERAL condyle and the PCL to the MEDIAL condyle — they cross.
Common student mistakes
- Siding the femur by the head alone without checking the linea aspera: holding it back-to-front gives the wrong side.
- Saying the hip capsule covers the whole neck behind: posteriorly it attaches only partway along the neck.
- Confusing the adductor tubercle (attachment of adductor magnus) with the medial epicondyle (tibial collateral ligament).
- Placing the patellar surface at the back: it is anterior; the intercondylar fossa is posterior.
Common exam questions
How do you determine the side of a femur?Show answer
Head upwards and pointing medially, linea aspera facing backwards; the head then points away from the side the bone belongs to (towards the midline).
Describe the blood supply of the head of the femur and its clinical importance.Show answer
Mainly retinacular branches of the medial circumflex femoral artery running along the neck, plus a usually small artery in the ligament of the head; displaced neck fractures can cause avascular necrosis.
List the muscles attached to the greater and lesser trochanters.Show answer
Greater: gluteus medius and minimus, piriformis, obturator internus with the gemelli, obturator externus (trochanteric fossa). Lesser: iliopsoas.
Name the structures attached to the linea aspera.Show answer
Adductor longus, brevis and magnus, the short head of biceps femoris, and the origins of vastus medialis and lateralis.
What is the difference between the intertrochanteric line and crest?Show answer
The line is anterior and gives attachment to the hip capsule and iliofemoral ligament; the crest is posterior, smooth and prominent, and carries the quadrate tubercle.
Where do the cruciate ligaments attach on the femur?Show answer
ACL to the medial surface of the lateral condyle; PCL to the lateral surface of the medial condyle; both within the intercondylar fossa.
Why is the femoral shaft oblique?Show answer
Because the hips are set wide apart in the pelvis while the knees lie close to the midline under the body.
Revision summary
- Longest and strongest bone; a long bone with head, neck, two trochanters, shaft and two condyles.
- Head points medially; linea aspera and intercondylar fossa face posteriorly.
- Greater trochanter: gluteus medius and minimus and short lateral rotators; lesser trochanter: iliopsoas.
- Intertrochanteric line in front (capsule, iliofemoral ligament); intertrochanteric crest behind (quadrate tubercle).
- Head blood supply mainly from the medial circumflex femoral artery via retinacular arteries; neck fractures risk avascular necrosis.
- Articulates with the acetabulum (hip), tibia and patella (knee).
Test yourself on the femur
Spotting questions on bones, sides and landmarks — untimed, with explanations.
Joints of the femur
References
- Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. 5th ed. Philadelphia: Elsevier; 2023.
- Moore KL, Dalley AF, Agur AMR. Moore's Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2023.
- Federative International Programme for Anatomical Terminology (FIPAT). Terminologia Anatomica. 2nd ed. FIPAT.library.dal.ca; 2019. fipat.library.dal.ca/TA2
- Kervyn G, Zielinski M, Vinent L, et al. Z-Anatomy: the libre 3D atlas of anatomy. Models derived from BodyParts3D, The Database Center for Life Science (CC BY-SA 2.1 JP). CC BY-SA 4.0. www.z-anatomy.com/
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