femur /ˈfiː.mər/ n. (pl. femora or femurs; also called the thigh bone)
Definition. The long bone of the thigh, extending from the hip to the knee. It is the longest, heaviest, and strongest bone in the human body and serves as the principal weight-bearing bone of the lower limb.
Etymology. From Latin femur, “thigh.” The adjectival form is femoral (e.g., femoral artery, femoral head).
Classification. A long bone of the appendicular skeleton; one per lower limb.
Gross anatomy. The femur is conventionally divided into three regions:
- Proximal end — comprises the rounded head (caput femoris), which articulates with the acetabulum of the hip bone; the neck (collum), connecting the head to the shaft; and two bony prominences for muscle attachment, the greater trochanter (lateral) and lesser trochanter (medial).
- Shaft (body / diaphysis) — a slightly bowed, cylindrical column bearing on its posterior surface a roughened ridge, the linea aspera, which serves as an attachment site for several thigh muscles.
- Distal end — expands into the medial and lateral condyles, separated posteriorly by the intercondylar fossa; the corresponding epicondyles provide ligamentous attachment, and the anterior patellar (trochlear) surface articulates with the patella (kneecap).
Articulations. Proximally, the femoral head forms the hip joint (a ball-and-socket synovial joint) with the acetabulum; distally, the condyles form the knee joint with the tibia and patella.
Function. Transmission and support of body weight during standing and locomotion; provision of leverage and attachment for major muscles of the hip and thigh; and, within its medullary cavity and trabecular bone, participation in hematopoiesis (blood cell formation).
Clinical significance. The femoral neck is a frequent site of fracture, particularly in older adults with osteoporosis, owing to its angulation and relative thinness; such fractures may compromise the blood supply to the head and lead to avascular (osteonecrosis) of the femoral head. The femoral shaft can fracture under high-energy trauma and may cause significant blood loss. In children and adolescents, the proximal growth plate is relevant in conditions such as slipped capital femoral epiphysis (SCFE). The femoral head is also commonly replaced or resurfaced in hip arthroplasty.
Related terms. femoral head; femoral neck; greater trochanter; linea aspera; acetabulum; hip joint; knee joint; diaphysis.
See also. tibia; patella; pelvis (hip bone); femoral neck fracture; hip arthroplasty.
Disclaimer. This glossary entry is provided for general informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment, and it is not a substitute for consultation with a qualified healthcare professional. Anatomical descriptions are presented in general terms and may not account for individual variation or specific clinical circumstances. No diagnostic or therapeutic outcome is implied or guaranteed. If you have concerns about an injury, pain, or any medical condition, seek the guidance of a licensed physician or other qualified provider. Neither the author nor the publisher assumes liability for any action taken on the basis of this content.