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 top top 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 connects the apex of the patella come the tibial tuberosity, and improves the way the quadriceps muscle pulls on the tibia.

In this short article we will talk about the gross and functional anatomy of the patellar tendon. Us will likewise explain the clinical relevance of the structure, and carry out a an introduction of vital points in ~ the end of the article.


Anatomy

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

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

A tendon is connective tissue that connects a muscle to a bone, and also the patellar ‘tendon’ in truth connects a bone come a bone (patella come tibial tuberosity). The correct name is thus the patellar ligament. There space though some fibers the the tendon that the quadriceps femoris muscle, the blend with the patellar "tendon" and also maybe this is the reason for this name issue.

The patellar ligament is around 5 centimeter in length. However, that length is not continuous and mostly increases from full expansion to 30 degrees of knee flexion.


The medial and lateral parts the quadriceps femoris descend on either side of the patella and also are inserted onto the upper anterior surface of the tibia. Lock merge into a continuous capsule, and form the medial and also lateral patellar retinacula. The posterior element of the patellar ligament is separated native the knee joint by one infrapatellar fat pad and a synovial membrane. An infrapatellar bursa also the end the patellar ligament from the tibia.


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Patellar ligament (lateral view)

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

Want to check your knowledge of the patella anatomy? Quiz questions are your an enig to success.

The patella, whose optimal thickness is between 2 and 3 cm, sits versus the femur in ~ a location which counts on the level of knee flexion. This rise in lever arm ensures that knee expansion is an ext efficient, and the action of quadriceps femoris is plainly transmitted v to the tibia.


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Clinical aspects

Osgood-Schlatter Disease- This is an apophysitis, i.e. Inflammation the a expansion plate, resulted in by extreme pulling that the patellar tendon ~ above the tibial tuberosity. It wake up in sporty teenagers whose tibia has not fully ossified.

Patellar tendon rupture- There space two possible types of rupture: a complete tear and a partial tear. The patellar tendon frequently ruptures proximally, close to the patellar origin. A complete tear leader to a high speak patella and requires surgical repair while a partial tear leader to tendinopathy and also can be cure conservatively.

Patellar reflex- This is a reflex arc the occurs in a relaxed lower limb, when the patellar tendon is struck. This lengthens the muscle slightly, which sends a signal to the spinal cord (L2-L4), which then sends one more signal come the agonist muscle (quadriceps femoris) to contract, and a signal to the hamstrings come relax. The an outcome is a slight absent of the knee. If the individual has brisk reflexes it have the right to be a sign of an top motor neurone lesion. Lacking reflex may be a sign of a lower motor neurone lesion.

ACL repair using a patellar tendon graft- In situations of anterior cruciate ligament rupture, a ar of the patellar tendon (ligament) deserve to be offered as a replacement. The ligament is passed v the tibia and the equivalent surface of the femur, in the exact same direction together the ACL (from a an ar just anterior to the intercondylar eminence that the tibial, to the posteromedial surface of the lateral femoral condyle).

Summary

The patella is a sesamoid bone that lies in the tendon the quadriceps femoris. The patellar tendon arises from the apex the the patella and its anterior and posterior surfaces.The patellar tendon inserts ~ above the tibial tuberosity.The patellar ligament is usually around 5 centimeter in length, yet its length varies with knee flexion.The patellar tendon must be called the patellar ligament, as it connects a bone to a bone (patella to tibial tuberosity), not a muscle to a bone as a tendon does.Osgood-Schlatter disease occurs once quadriceps femoris pulls on the expansion plate of the tibial tuberosity. It occurs most generally in adolescents.

Sources

References:

Frank H.Netter MD: Atlas of person Anatomy, 5th 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 extension (lateral view) - Paul Kim

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