Proximal epiphysis of the femur
The upper end of the femur has a complex structure, as it bears the main load during body weight transmission. Located here is the femoral head (caput femoris), which participates in the formation of the joint with the acetabulum. On the head itself, there is a small depression — the fovea of the head (fovea capitis femoris).
Following the head is a narrowed part — the femoral neck (collum femoris). At the base of the neck there are two massive bony prominences called trochanters (trochanteres):
- Greater trochanter (trochanter major) — located laterally. Near it is the trochanteric fossa (fossa trochanterica).
- Lesser trochanter (trochanter minor) — located medially.
Anteriorly, between the trochanters runs the intertrochanteric line (linea intertrochanterica), while posteriorly they are connected by the more massive intertrochanteric crest (crista intertrochanterica). In some people, an additional third trochanter (trochanter tertius) may be present.
Shaft of the femur (diaphysis)
The shaft of the femur (corpus femoris) has a rounded cross-section. Its anterior surface is completely smooth, whereas the posterior surface prominently features the linea aspera (linea aspera).
The linea aspera consists of two lips:
- Medial lip (labium mediale).
- Lateral lip (labium laterale), which superiorly transitions into the gluteal tuberosity (tuberositas glutea).
Additional lines diverge from these lips in different directions. The pectineal line (linea pectinea) directs upward. The medial and lateral supracondylar lines (linea supracondylaris medialis et lateralis) extend downward. Diverging in the lower third of the femur, they enclose a triangular area on the posterior surface — the popliteal surface (facies poplitea).
Distal epiphysis
The lower end of the femur is expanded and forms two large articular structures — condyles (condyli). The medial condyle (condylus medialis) and lateral condyle (condylus lateralis) articulate with the tibia. Protruding laterally above the condyles are the corresponding epicondyles (epicondylus medialis et lateralis).
The distal epiphysis features important surfaces and fossae:
- Patellar surface (facies patellaris) — located anteriorly and serves for articulation with the patella.
- Intercondylar fossa (fossa intercondylaris) — located posteriorly, separating the condyles.
- Intercondylar line (linea intercondylaris) — separates the intercondylar fossa from the popliteal surface located above.
Anatomy of the patella
The patella (patella) is a crucial element of knee joint biomechanics. Its structure comprises a broad base (basis patellae) directed upward and a narrowed apex (apex patellae) directed downward.
The anterior surface (facies anterior) of the bone is convex and rough due to tendon attachments. The posterior articular surface (facies articularis) articulates with the femur. Two characteristic depressions corresponding precisely to the relief of the femoral condyles can be observed on it.
Determining the side of the femur
To correctly determine whether a bone is right or left, follow three simple steps:
- Position the bone vertically: the proximal end (with the head and neck) must be at the top, and the distal end (with the condyles) at the bottom.
- Locate the anterior and posterior surfaces: anteriorly, the diaphysis is smooth, while posteriorly you will see the linea aspera and the deep intercondylar fossa at the bottom.
- Orient the trochanters: the greater trochanter always faces laterally (outward), and the lesser trochanter faces medially (inward).
Briefly: answers to topical questions
Which muscles attach to the greater trochanter of the femur?
The tendons of several pelvic and thigh muscles attach to the greater trochanter of the femur.
- Piriformis muscle (m. piriformis) — attaches to the apex of the greater trochanter.
- Gluteus medius muscle (m. gluteus medius) — also attaches to the apex of the greater trochanter.
- Obturator internus muscle (m. obturatorius internus) and gemelli muscles (mm. gemelli) — their tendons run transversely and attach to the greater trochanter.
Additionally, the vastus lateralis muscle (m. vastus lateralis) originates from the greater trochanter.
Into which lines do the lips of the linea aspera transition proximally?
Proximally, the lips of the linea aspera give rise to the pectineal line (linea pectinea), and the lateral lip transitions into the gluteal tuberosity (tuberositas glutea).
With which bones does the femur form joints?
The femur forms joints with three skeletal bones:
- Hip bone (os coxae) — the femoral head articulates with the acetabulum of the hip bone, forming the hip joint.
- Tibia (tibia) — the femoral condyles articulate with the proximal end of the tibia, participating in the formation of the knee joint.
- Patella (patella) — the patellar surface of the distal femoral epiphysis articulates with the articular surface of the patella.
Which structure attaches to the fovea of the femoral head?
The ligament of the head of the femur (lig. capitis femoris) attaches to the fovea of the femoral head (fovea capitis femoris). This intracapsular ligament originates from the margins of the acetabular notch and the transverse ligament. Covered by a synovial membrane, it acts as an elastic cushion to mitigate shocks in the hip joint and serves as a pathway for blood vessels supplying the femoral head.
The tendon of which muscle attaches to the base of the patella?
The tendon of the quadriceps femoris muscle (m. quadriceps femoris) attaches to the base of the patella (basis patellae). Some of its fibers weave into the joint capsule; its medial and lateral bundles form the patellar retinacula (retinacula patellae).
To avoid confusing the structures between the trochanters: the anterior relief is smoother, featuring a LINE (linea intertrochanterica), whereas the posterior relief is robust, featuring a CREST (crista intertrochanterica).
Class and exam questions
To which class of bones does the femur belong?
This is a typical long tubular bone, which is the largest in the human skeleton.
How to distinguish the anterior surface of the femur from the posterior one?
The anterior surface of the bone shaft is smooth, while the posterior surface features the linea aspera and an intercondylar fossa at the distal end.
Which bones do the femoral condyles articulate with?
The medial and lateral femoral condyles articulate with the tibia.
Where is the apex of the patella located?
The apex of the patella (apex patellae) is directed downward, whereas its base is located superiorly.
What else to study on this topic
- Fovea of the femoral head (fovea capitis femoris) and its functional significance.
- Third trochanter (trochanter tertius): incidence and anatomical meaning.
- Gluteal tuberosity and its connection with the lateral lip of the linea aspera.
- Composition of the leg skeleton (Crus) and foot bones (Ossa pedis) as part of the free lower limb.
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