Anatomy

To learn more about the patellar tendon anatomy and adjacent structures, watch the video below.

The quadriceps femoris is a knee extensor muscle consisting of the rectus femoris, vastus lateralis, vastus medialis and deeper vastus intermedius. All heads of the quadriceps unite to form the quadriceps tendon, that is attached to the bases and sides of the patella. The patellar tendon is the continuation of the quadriceps tendon. It runs inferiorly, connecting the inferior pole of patella (apex) to the tibial tuberosity.^1,2,3

The posterior surface of the patellar tendon is separated from the synovial membrane of the joint by a large infrapatellar (Hoffa) fat pad, and from the tibia by the deep infrapatellar bursa. The anterior surface of the patellar tendon is separated from the skin by the superficial infrapatellar bursa.^1,2,3

In adults, the patellar tendon is around 25–40 mm wide in the coronal plane and 4–5 mm deep in the sagittal plane and 4–6 cm long. Macroscopically it appears white, glistening and stringy with collagen fiber arranged in parallel fashion.^1,2,3

Vascular supply

The patellar tendon receives its vascularization through the anastomotic ring which lies in the thin layers of loose connective tissue covering the dense fibrous expansion of the rectus femoris.¹

The main contributors are the medial superior genicular artery, the medial inferior genicular artery, the lateral superior genicular artery, lateral inferior genicular artery, and the anterior tibial recurrent artery.^1,4

Structure function

The patellar tendon acts as a passive stabilizer of the patella and transmits the forces generated by the quadriceps contraction to the tibia to produce movement. This structure is typically oriented slightly lateral to the long axis of the tibia, thereby creating a slight lateral pull on the patella.⁵ Together, the quadriceps muscle, quadriceps tendon, patella, and patellar tendon are referred to as the knee extensor mechanism.²

Test your knowledge – Quiz

Now that you learned all you need to know about the patellar tendon and adjacent structures, check your knowledge by taking the quiz below.