Femur Anatomy: Bony Landmarks & Muscle Attachment
The femur is classed as a long bone, only bone in the thigh, and the longest bone in the body. Its length varies from one-fourth to one-third of that of the body; The main function of the femur is to transmit forces from the tibia to the hip joint.The femur is well covered with muscles so that only its superior and inferior ends are palpable.
Parts of the Femur
It can be divided into three areas; proximal end, shaft and the distal end.
The Proximal end consists of a head, neck, and two trochanters.The head faces superiorward, medialward, and slightly anteriorward .The proximal area of the femur forms the hip joint with the pelvis. There are also two bony ridges connecting the two trochanters.
Head – Connects with the acetabulum of the pelvis to make the hip joint. It has a glossy surface with a depression on the medial position; for the attachment of the ligament of head of the femur.
Neck – Attaches the head of the femur with the shaft. It is cylindrical, projecting in a superior and medial direction – this angle of projection permits for an enhanced range of movement at the hip joint.
Greater trochanter – A projection of bone that starts from the anterior aspect, just parallel to the neck. It is angled superiorly and posteriorly and can be found on both the anterior and posterior sides of the femur.
The site of attachment for the muscles gluteus medius, gluteus minimus, and piriformis.
Lesser trochanter – Shorter than the greater trochanter. It extends from the posteromedial side of the femur, just under to the neck-shaft junction.
Intertrochanteric line – A ridge of bone that runs in an inferomedial and connecting the two trochanters together. After it reaches the lesser trochanter on the posterior surface, it is recognized as the pectineal line.
Intertrochanteric crest – A ridge of bone that connects the two trochanters together. It is found on the posterior surface of the femur. There is a rounded tubercle on its superior half, this is designated the quadrate tubercle, where the quadratus femoris attaches.The distal fragment is pulled upwards and rotated laterally.
Shaft of the Femur
The shaft descends in a slight medial direction. This brings the knees closer to the body’s center of gravity, increasing stability.
On the posterior surface of the femoral shaft, a roughened ridges of bone, these are also described as the linea aspera.
Proximally, the medial border of the linea aspera fits the pectineal line. The lateral border enhances the gluteal tuberosity, where the gluteus maximus attaches.
Distally, the linea aspera increases and forms the floor of the popliteal fossa, the medial and lateral borders form the medial and lateral supracondylar lines. The medial supracondylar line stops at the adductor tubercle, where the adductor magnus muscle attaches.
The distal end is marked by the presence of the medial and lateral condyles, which join with the tibia and patella, forming the knee joint.
Medial and lateral condyles – Rounded areas at the end of the femur. The posterior and inferior surfaces connect with the tibia and menisci of the knee, while the anterior surface connects with the patella.
Medial and lateral epicondyles – Bony elevations on the non-articular areas of the condyles.
They are the area of attachment of some muscles and the collateral ligaments of the knee joint.
Intercondylar fossa – A depression found on the posterior surface of the femur, it lies in between the two condyles. It contains two facets for attachment of internal knee ligaments.
Facet for attachment of the posterior cruciate ligament – Found on the medial wall of the intercondylar fossa, it is a large rounded flat face, where the posterior cruciate ligament of the knee attaches.
Facet for attachment of anterior cruciate ligament – Found on the lateral wall of the intercondylar fossa, it is smaller than the facet on the medial wall and is where the anterior cruciate ligament of the knee attaches.