The lower extremity of femur (or distal extremity) is the lower end of the
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...
(thigh bone) in human and other animals, closer to the knee. It is larger than the
upper extremity of femur
The upper extremity, proximal extremity or superior epiphysis of the femur is the part of the femur closest to the pelvic bone and the trunk. It contains the following structures:
* Femoral head including the fovea
* Femur neck
* Greater trochan ...
, is somewhat cuboid in form, but its transverse diameter is greater than its antero-posterior; it consists of two oblong eminences known as the
lateral condyle and
medial condyle.
Condyles
Anteriorly, the condyles are slightly prominent and are separated by a smooth shallow articular depression called the
patella surface. Posteriorly, they project considerably and a deep notch, the
intercondylar fossa of femur
The intercondylar fossa of femur (intercondyloid fossa of femur, intercondylar notch of femur) is a deep notch between the rear surfaces of the medial and lateral epicondyle of the femur, two protrusions on the distal end of the femur (thigh bon ...
, is present between them.
The
lateral condyle is the more prominent and is the broader both in its antero-posterior and transverse diameters, the
medial condyle is the longer and, when the femur is held with its body perpendicular, projects to a lower level.
When, however, the femur is in its natural oblique position the lower surfaces of the two condyles lie practically in the same horizontal plane.
The condyles are not quite parallel with one another; the long axis of the lateral is almost directly antero-posterior, but that of the medial runs backward and medialward.
Their opposed surfaces are small, rough, and concave, and form the walls of the intercondylar fossa.
This fossa is limited above by a ridge, the
intercondyloid line, and below by the central part of the posterior margin of the patellar surface.
The
posterior cruciate ligament
The posterior cruciate ligament (PCL) is a ligament in each knee of humans and various other animals. It works as a counterpart to the anterior cruciate ligament (ACL). It connects the posterior intercondylar area of the tibia to the medial cond ...
of the
knee joint is attached to the lower and front part of the medial wall of the fossa and the
anterior cruciate ligament
The anterior cruciate ligament (ACL) is one of a pair of cruciate ligament
Cruciate ligaments (also cruciform ligaments) are pairs of ligaments arranged like a letter X. They occur in several joints of the body, such as the knee joint and th ...
to an impression on the upper and back part of its lateral wall.
Epicondyles
Each condyle is surmounted by an elevation, the
epicondyle.
The
medial epicondyle is a large convex eminence to which the
medial collateral ligament
The medial collateral ligament (MCL), or tibial collateral ligament (TCL), is one of the four major ligaments of the knee. It is on the medial (inner) side of the knee joint in humans and other primates. Its primary function is to resist outwar ...
of the knee-joint is attached.
At its upper part is the
adductor tubercle
The adductor tubercle is a tubercle on the lower extremity of the femur. It is formed where the medial lips of the linea aspera end below at the summit of the medial condyle. It is the insertion point of the tendon of the vertical fibers of the ...
, and behind it is a rough impression which gives origin to the medial head of the
gastrocnemius
The gastrocnemius muscle (plural ''gastrocnemii'') is a superficial two-headed muscle that is in the back part of the lower leg of humans. It runs from its two heads just above the knee to the heel, a three joint muscle (knee, ankle and subtalar ...
.
The
lateral epicondyle, smaller and less prominent than the medial, gives attachment to the
fibular collateral ligament of the knee-joint.
Directly below it is a small depression from which a smooth well-marked groove curves obliquely upward and backward to the posterior extremity of the condyle.
This groove is separated from the articular surface of the condyle by a prominent lip across which a second, shallower groove runs vertically downward from the depression.
In the fresh state these grooves are covered with cartilage.
The
popliteus
The popliteus muscle in the leg is used for unlocking the knees when walking, by laterally rotating the femur on the tibia during the closed chain portion of the gait cycle (one with the foot in contact with the ground). In open chain movements ...
arises from the depression; its tendon lies in the oblique groove when the knee is flexed and in the vertical groove when the knee is extended.
Above and behind the lateral epicondyle is an area for the origin of the lateral head of the gastrocnemius, above and to the medial side of which the
plantaris
The plantaris is one of the superficial muscles of the superficial posterior compartment of the leg, one of the fascial compartments of the leg.
It is composed of a thin muscle belly and a long thin tendon. While not as thick as the achilles te ...
arises.
Articular surface
The articular surface of the lower end of the femur occupies the anterior, inferior, and posterior surfaces of the condyles.
Its front part is named the patellar surface and articulates with the patella; it presents a median groove which extends downward to the
intercondyloid fossa and two convexities, the lateral of which is broader, more prominent, and extends farther upward than the medial.
The lower and posterior parts of the articular surface constitute the tibial surfaces for articulation with the corresponding condyles of the
tibia
The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...
and
menisci.
These surfaces are separated from one another by the intercondyloid fossa and from the patellar surface by faint grooves which extend obliquely across the condyles.
The lateral groove is the better marked; it runs lateralward and forward from the front part of the intercondyloid fossa, and expands to form a triangular depression.
When the knee-joint is fully extended, the triangular depression rests upon the anterior portion of the lateral meniscus, and the medial part of the groove comes into contact with the medial margin of the lateral articular surface of the tibia in front of the lateral tubercle of the
tibial intercondyloid eminence.
The medial groove is less distinct than the lateral.
It does not reach as far as the intercondyloid fossa and therefore exists only on the medial part of the condyle; it receives the anterior edge of the medial meniscus when the knee-joint is extended.
Where the groove ceases laterally the patellar surface is seen to be continued backward as a
semilunar
Semilunar can refer to:
* Semilunar valves
* Semilunar ganglion, or the trigeminal ganglion
* An older name for the Lunate bone
The lunate bone (semilunar bone) is a carpal bone in the human hand. It is distinguished by its deep concavity and ...
area close to the anterior part of the intercondyloid fossa; this semilunar area articulates with the medial vertical facet of the patella in forced flexion of the knee-joint.
The tibial surfaces of the condyles are convex from side to side and from before backward. Each presents a double curve, its posterior segment being an arc of a circle, its anterior, part of a cycloid.
Additional images
File:Gray244.png, Right femur. Anterior surface.
File:Gray245.png, Right femur. Posterior surface.
References
Bones of the lower limb
Femur
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