Author: Shahab Shahid MBBS•Reviewer: Jerome GoffinLast reviewed: September 30, 2021Reading time: 6 minutes


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Patellar ligament (ventral view)

The quadriceps femoris is a four-headed muscle that inserts onto the tibial tuberosity. It extends the knee, and one head (rectus femoris) flexes the hip.

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The patella is a sesamoid bone that lies in ~ the quadriceps tendon. The patellar tendon associate the apex of the patella come the tibial tuberosity, and also improves the method the quadriceps muscle pulls on the tibia.

In this post we will comment on the gross and functional anatomy of the patellar tendon. We will also explain the clinical relationship of the structure, and provide a review of key points in ~ the end of the article.


Anatomy

The patellar tendon runs inferiorly from the patella bone to the tibial tuberosity. The patella is a big sesamoid (a bone within a tendon) bone v a triangle transverse cross-section, that lies in ~ the quadriceps tendon. One more example the a sesamoid bone is the pisiform carpal bone the lies within the tendon of flexor carpi ulnaris.

The patellar tendon originates in the patellar apex and attaches to the tibial tuberosity, i beg your pardon is a small bony bump on the anterior facet of the tibia. The patellar tendon is technically not called correctly.

A tendon is connective tissue that connect a muscle come a bone, and the patellar ‘tendon’ in reality connects a bone to a bone (patella to tibial tuberosity). The correct surname is as such the patellar ligament. There are though part fibers the the tendon that the quadriceps femoris muscle, the blend through the patellar "tendon" and also maybe this is the reason for this surname issue.

The patellar ligament is about 5 cm in length. However, that is length is not continuous and mostly boosts from full expansion to 30 levels of knee flexion.


The medial and lateral parts of quadriceps femoris descend on either next of the patella and are inserted onto the top anterior surface ar of the tibia. They merge into a continuous capsule, and type the medial and lateral patellar retinacula. The posterior facet of the patellar ligament is separated indigenous the knee joint by an infrapatellar fat pad and a synovial membrane. One infrapatellar bursa also separates the patellar ligament indigenous the tibia.


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Patellar ligament (lateral view)

The duty of the patella is to increase the size of the lever arm of the patellar tendon and therefore permit quadriceps femoris come exert a greater moment roughly the axis the rotation that the knee because that a provided level the muscle contraction 보다 in the absence of a patella.

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The patella, whose height thickness is in between 2 and 3 cm, sits against the femur at a location which counts on the level of knee flexion. This rise in bar arm ensures the knee expansion is much more efficient, and the action of quadriceps femoris is plainly transmitted through to the tibia.


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Clinical aspects

Osgood-Schlatter Disease- This is one apophysitis, i.e. Inflammation the a development plate, caused by too much pulling that the patellar tendon top top the tibial tuberosity. It wake up in sporty adolescents whose tibia has actually not completely ossified.

Patellar tendon rupture- There are two possible types the rupture: a complete tear and also a partial tear. The patellar tendon often ruptures proximally, close to the patellar origin. A finish tear leader to a high riding patella and also requires surgical repair while a partial tear leader to tendinopathy and can be treated conservatively.

Patellar reflex- This is a reflex arc that occurs in a relaxed reduced limb, as soon as the patellar tendon is struck. This lengthens the muscle slightly, which sends a signal come the spinal cord (L2-L4), which then sends another signal come the agonist muscle (quadriceps femoris) come contract, as well as a signal to the hamstrings come relax. The an outcome is a slight kick of the knee. If the individual has brisk reflexes it can be a sign of an upper motor neurone lesion. Absent reflex may be a authorize of a reduced motor neurone lesion.

ACL repair using a patellar tendon graft- In instances of anterior cruciate ligament rupture, a ar of the patellar tendon (ligament) have the right to be provided as a replacement. The ligament is passed with the tibia and also the equivalent surface that the femur, in the very same direction together the ACL (from a an ar just anterior to the intercondylar eminence the the tibial, come the posteromedial surface ar of the lateral femoral condyle).

Summary

The patella is a sesamoid bone that lies in the tendon of quadriceps femoris. The patellar tendon arises from the apex of the patella and also its anterior and also posterior surfaces.The patellar tendon inserts onto the tibial tuberosity.The patellar ligament is usually around 5 cm in length, but its size varies with knee flexion.The patellar tendon should be named the patellar ligament, as it associate a bone to a bone (patella come tibial tuberosity), no a muscle to a bone as a tendon does.Osgood-Schlatter an illness occurs once quadriceps femoris traction on the development plate the the tibial tuberosity. It occurs most frequently in adolescents.

Sources

References:

Frank H.Netter MD: Atlas of human Anatomy, fifth Edition, Elsevier Saunders.Chummy S.Sinnatamby: Last’s Anatomy local and Applied, 12th Edition, Churchill Livingstone Elsevier.Richard L. Drake, A. Wayne Vogl, Adam. W.M. Mitchell: Gray’s Anatomy for Students, 2nd Edition, Churchill Livingstone Elsevier.

Illustrators:

Patellar ligament (ventral view) - Liene ZnotinaPatellar ligament (lateral view) - Paul KimKnee expansion (lateral view) - Paul Kim

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