Patella bone

INTRODUCTION

- Largest sesamoid bone.

- Developed in the tendon of the quadriceps femoris

ANATOMICAL POSITION

- Anterior rough surface is placed anteriorly with its apex pointing downwards.

- Posterior articular area is placed posteriorly.

SIDE DETERMINATION

- Triangle in shape with its apex downwards(apex is non-articular structure in patella which lies inferiorly).

- Posterior articular surface is divided by a vertical ridge into larger lateral and a smaller medial areas.

- When bone is laid on the table, it rests on broad lateral articular area which determine its side.

PARTS 

- Has an apex, three borders (superior, lateral and medial) and two surfaces (anterior and posterior).

NOTE :- During various phases of movements of the knee, different portions of patella articulates during extention. Middle pair during beginning of flexion. Upper pair during midflexion. Medial strip during full extention of knee.

ATTACHMENTS

A. Muscles (only insertion)

1. Rectus femoris

2. Vastus intermedius

3. Vastus lateralis

4. Vastus medialis

These four muscles  are called quadriceps femoris.

CLINICAL ANATOMY

1. Patella may get fractured.

2. Bursitis occurs in prepatellar and subcutaneous infrapatellar bursae.

RELATIONS

1. Tibial nerve

2. Common peroneal nerve

3. Fibular nerve