Patella

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Bone: Patella
Knee diagram
Gray's	subject #60 255
MeSH	Patella

The patella or kneecap is a thick, triangular bone which articulates with the femur and covers and protects the front of the knee joint. It is the largest sesamoid bone in the human body. It is attached to the tendon of the quadriceps femoris muscle, which contracts to straighten the leg. The vastus intermedialis muscle is attached to the base of patella. The vastus lateralis and vastus medialis are attached to lateral and medial borders of patella respectively.

The patella is stabilised by the insertion of vastus medialis and the prominence of the anterior femoral condyles, which prevent lateral dislocation during flexion. The retinacular fibres of the patella also stabilise it during exercise.

The primary functional role of the patella is knee extension. The patella increases the leverage that the tendon can exert on the femur by increasing the angle at which it acts.

The patella ossifies between the ages 2-6 years. In some people it may be absent congenitally or hypoplastic. In 2% of the population there is a bipartite patella, which is usually asymptomatic.

Regarding non-human animals, the patella is fully developed only in placental mammals; marsupials have only rudimentary, non-ossified patellae.^[1]

See also

• Patellar reflex

Additional images

Lower extremity	Patella ant.jpg Left patella - anterior aspect	Patella post.jpg Left patella - posterior aspect	Right knee-joint. Anterior view.
Sagittal section of right knee-joint.	Capsule of right knee-joint (distended). Lateral aspect.	Front and medial aspect of right thigh.	Lateral aspect of right leg.

References

External links

• SUNY Figs 12:01-15

v • d • e Bones of lower limbs
Femur	head of femur (fovea capitis femoris) · neck of femur · greater trochanter · trochanteric fossa · lesser trochanter · tubercle of the femur · intertrochanteric line · intertrochanteric crest · linea quadrata body (linea aspera, third trochanter, pectineal line, adductor tubercle) lower extremity (lateral condyle, medial condyle, lateral epicondyle, medial epicondyle, patellar surface)
Tibia	upper extremity medial condyle · lateral condyle · intercondyloid eminence · tuberosity of the tibia · posterior intercondyloid fossa · anterior intercondyloid fossa body soleal line lower extremity medial malleolus
Fibula	head of fibula · body of fibula · lateral malleolus
Tarsus	calcaneus (sustentaculum tali, trochlear process) · talus · navicular · cuboid · cuneiform (medial, intermediate, lateral)
Metatarsus	1st metatarsal · 2nd · 3rd · 4th · 5th
Other	patella · phalanges of the foot

ca:Patel·la

de:Kniescheibeeo:Patelo fr:Rotule id:Tulang lutut it:Rotula (anatomia) he:עצם הפיקה la:Patella lt:Girnelė nl:Knieschijf ja:膝蓋骨 no:Patellask:Jabĺčko fi:Polvilumpio te:జానుఫలకము uk:Надколінник

Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .