PATELLA: osteology, myology,side determination, clinical anatomy

Bone:patella

Features

• Also called knee cap.
• Patella is a sesamoid bone in the tendon of quadriceps femoris muscle.
• It is the largest sesamoid bone in the body.

Side determination

• The patella is shaped like a disc .
• It has a process that projects inferiorly .
• The anterior surface is rough with several vertical striations.
• The posterior surface has a large articular fascet which is subdivided into large lateral and small medial areas.

Osteology

• Roughly triangular in outline.
• It has anterior and posterior surface that are separated by three borders (superior, medial and lateral).
• The superior border is also called the base .
• The medial and lateral borders are the medial and lateral margins of the bone.
• The inferior part of the bone shows the downward projection called the apex.
• The anterior surface is rough and can be felt through  the overlying skin.
• It is slightly convex and is vertically striated by the fibres which run over it.
• Posterior surface is articular . It articulates with the patellar surface on the anterior aspect of the condyle of the femur.
• It consists of a large lateral part and a smaller medial part, the two parts are separated by a ridge.
• The lateral and medial parts are further subdivided by faint ridges into superior, middle and inferior fascet.

Myology

• The superior border gives attachment to the quadriceps femoris.
• The apex and the adjacent part of posterior surface gives attachment to the ligamentum patellae.
• The medial and lateral borders receive fibres of vastus medialis and lateralis respectively and also fibres of fascia lata.
• The collected fibres of the concerned muscle and the fascia Lata together  forms the medial and lateral patellar retinaculum respectively.

Ossification

• The patella ossifies from several center that appear between 3rd and 6th year of life . The  centres soon fuse with each other.