Bones of the Legs & Knees

A normal human leg and knee is made up of 4 bones on each side.  The legs and knee comprise a total of 8 bones (roughly 3.9%) out of the total 206 bones in the human adult skeleton.  The bones of the knee and leg are made up of the innominate or hip bone (fusion of the ilium, ischium, and pubis), femur, tibia, fibula, and patella (kneecap) on each side.

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Femur Femur: Head Femur: Neck Femur: Lesser Trochanter Femur: Greater Trochanter Femur: Medial Condyle Femur: Lateral Condyle Patella Tibia Tibia: Medial Condyle Tibia: Lateral Condyle Fibula

Additional Information

Femur Head

The femoral head is joined to the body of the femur by the anatomical neck and forms approximately two-thirds of a sphere. It articulates with the acetabulum of the hip bone. Approximately 40% of the femoral head is covered by the bony acetabulum of the hip at any position of hip motion.

Attachments
Near its center there is a small pit or fovea for the attachment of the ligament of the head of the femur.
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Femur Neck

The neck of the femur joins the head of the femur to the body. The femoral neck is approximately three-quarters the diameter of the femoral head and this relationship in size allows the femoral head to be deeply seated within its acetabular socket without compromising the stability or range of motion.
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Lesser Trochanter

The lesser trochanter is a conical projection, which lies posteromedially at the junction of the body and the neck of the femur.

It is joined to the greater trochanter anteriorly by a thin intertrochanteric line and posteriorly by a thick intertrochanteric crest.

Attachments
It gives attachment to psoas major, part of iliacus and pectineus.
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Greater Trochanter

The greater trochanter is a large quadrangular projection from the upper lateral part of the femur, at the junction of the neck and the body.

Attachments
It gives attachment to: obturator externus and internus, piriformis, gluteus minimus and gluteus medius.
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Femur

General information
The femur is the longest bone in the human body. It has a unique shape, being long but acutely angled at its proximal end. The rounded proximal end is called the femoral head, and the neck of the femur connects the head to the shaft, making an angle between the neck and the shaft of approximately 125°. There are two trochanters at the proximal end of the shaft: the greater (larger and more lateral) and the lesser (smaller and more medial) trochanters. Further, there is a raised portion of bone, known as the intertrochanteric crest, between the greater and lesser trochanters on the posterior side of the femur. On the anterior side, a rough area of bone known as the intertrochanteric line runs between the two trochanters.

At the distal end of the femur there are two condyles that serve as areas for articulation with the tibia. A somewhat narrow area between the two condyles can be observed and this area, the intercondylar notch, will appear larger as one looks on the posterior aspect of the bone. On the medial side and distal end, there is a small elevation of bone where the tendon of adductor magnus attaches - this area is called the adductor tubercle.

Articulations
At its proximal end, the femur articulates with the hip bone at the acetabulum. The distal end of the femur joins the plateaus of the tibia forming the knee joint. The posterior surface of the patella articulates with the intercondylar area of the femur.

Muscle attachments
Hip flexors, extensors, and rotators attach at or near the proximal end of the femur. These include such muscles as iliacus and psoas major (iliopsoas) on the anterior surface of the femur; quadratus femoris and the gluteal muscles on the posterior and lateral surfaces; and the gemelli, piriformis, and obturators on the medial aspect of the greater trochanter. The shaft of the femur serves as the point of attachment to the adductor muscles, the quadriceps muscles, and the short head of the biceps femoris. Distally on the femur, muscles of the calf (gastrocnemius and plantaris) arise just above the condyles on the posterior side of the femur and the popliteus manages to penetrate the joint capsule and attach on the lateral femoral condyle.
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Patella

General information
The patella is the largest sesamoid bone of the human body. It is enveloped by the quadriceps tendon from the proximal aspect of the knee joint and this soft tissue becomes the patellar ligament inferior to the patella.

Articulations
The posterior surface of the patella articulates with the intercondylar area of the femur. The patella has no other bony articulations.

Muscle attachments
The attachments to the patella are via the quadriceps tendon, into which the vasti muscles and rectus femoris attach. There are no muscles attaching directly onto the patella.
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Medial Condyle

FEMUR
The medial and lateral femoral condyles are situated at the distal end of the femur. Each condyle possesses articular and non-articular surfaces. The articular surfaces articulate with the corresponding medial and lateral tibial condyles.

The lateral surface of the medial condyle lies within the joint capsule and forms the medial wall of the intercondylar fossa.

Attachments
It gives attachment to the proximal (upper) end of the posterior cruciate ligament, the anterior and posterior menisco-femoral ligaments and the aponeurotic tendon of adductor magnus.

TIBIA
The upper end of the tibia is transversely expanded into two prominences, the lateral and medial tibial condyles. Both are smooth, gently concave articular areas that articulate with the condyles of the femur.

Attachments
The medial condyle gives attachment to semimembranosus and to the medial meniscus.
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Lateral Condyle

FEMUR
The medial and lateral femoral condyles are situated at the distal end of the femur. Each condyle possesses articular and non-articular surfaces. The articular surfaces articulate with the corresponding medial and lateral tibial condyles.

The medial surface of the lateral condyle is non-articular and lies within the joint capsule forming the lateral wall of the intercondylar fossa.

Attachments
It gives attachment to the proximal (upper) end of the anterior cruciate ligament.

TIBIA
The upper end of the tibia is transversely expanded into two prominences, the lateral and medial tibial condyles. Both are smooth, gently concave articular areas that articulate with the condyles of the femur.

The lateral tibial condyle overhangs the lateral aspect of the tibial shaft to articulate with the fibular head.

Attachments
The lateral tibial condyle gives attachment to the lower end of the ilio-tibial tract and to the lateral meniscus.
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Tibia

General information
The tibia is the major weight bearing bone of the leg - the fibula shares very little in that capacity. The tibia has two surfaces on its proximal end known as the tibial condyles. The articular area of the condyle, specifically, on the tibial plateau, is shorter on the lateral side than on the medial side, although the lateral tibial condyle appears longer than the medial condyle. A raised area of bone lies between the two plateaus - the intercondylar eminence. A short distance distal from the articular area is a raised portion of bone on the anterior surface and upper end of the tibial shaft known as the tibial tuberosity: the point of attachment of the quadriceps muscles. Just medial to the tibial tuberosity is another area for muscle attachments, the medial tibial flare. This is the area of attachment of the "pes anserine group", a group of three muscles from the thigh that converge at this location. On the distal end of the tibia, the medial projection of bone is called the medial, or tibial, malleolus. The lateral side of this end of the bone has a shallow area for the articulation with the fibula, the fibular notch.

Articulations
Proximally the tibia articulates with condyles of the femur. The fibula articulates with the lateral side of the tibia and has two points where the two bones actually contact one another; proximally at the lateral tibial flare and distally at the fibular notch. On the inferior surface, the tibia articulates with the talus.

Muscle attachments
The tibia serves as a point of attachment for muscles of the thigh as well as muscles of the leg. The hamstrings cross the knee joint posteriorly and semimembranosus remains posterior to attach to the tibia while the biceps femoris splits away laterally and the semitendinosus continues distally and medially to attach as the most posterior tendon of the pes anserine group. On the medial side of the thigh, gracilis crosses the knee joint and attaches as the middle member of the pes anserine group.
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Fibula

General information
The fibula is the smaller of the two bones of the leg. It lies lateral to the tibia and bears virtually no body weight. Both the proximal and distal ends of the fibula are somewhat rounded, the proximal being the fibular head while the distal end is slightly more flattened and forms the lateral malleolus. The rounded head has a projection from its superior surface, the styloid process or apex. The distal end has a flattened surface for articulation with the lateral side of the talus as well as a more medial depression for articulation with the medial malleolus.

Articulations
Both proximally and distally, the fibula articulates with the tibia at the tibiofibular joint (proximal and distal tibiofibular joints). Inferiorly, the fibula has a slight area of contact with the talus.

Muscle attachments
The fibular head is the point of attachment of biceps femoris. The lateral surface of the shaft of the bone is the area of attachment for peroneus longus and brevis, while the anterior surface of the bone is the location of peroneus tertius. More superiorly on the anterior surface is the attachment of both extensor digitorum longus and extensor hallucis longus. Posteriorly, the fibula serves as points of attachment to soleus proximally and flexor hallucis longus and tibialis posterior more distally.
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