Answer
The patella is classified as a sesamoid bone because it develops in a tendon. Other sesamoid bones include the pisiform, other bones of the foot, and several bones of the hand.
The term "sesamoid", which is derived from the Greek "sesamon" (seed of the sesame plant), is used to describe sesamoid bones because of the similarity of the shapes of these bones to the unique ovoid, semi-triangular shape of sesame seeds.
Work Step by Step
Sesamoid bones by definition are bones that develop in the tendons( or joint capsules). Sesamoid bones are not present in babies at birth. In the case of the patella , the cartilaginous precursor of the bone begins to calcify in the tendon of the quadriceps femoris muscle during the 3-6 year period of life. By age 10-12 the patella is fully formed-- though further calcification may continue for a few more years.
Sesamoid bones are also found at various places in the hands: these include the metacarpo-phalangeal and the interphalangeal joints of the thumb, and the metacarpo-phalangeal joint of the little finger. There are also sesamoid bones under the metatarso-phalangeal joint of the great toe.
The patella serves the following functions:
1. It protects the knee joint
2. It increases the leverage of the quadriceps femoris muscle.
3. When it tracts properly, it maintains the tendon in position as the knee is bent and straightened.
