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Anatomy Overview

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MUSCLE ACTIONS OF THE KNEE JOINT
TABLE KEY:    Primary muscle    Secondary muscles
Sagittal Plane Flexion Extension
 

Semimembranosus

Semitendinosus

Biceps femoris (long and short heads)

Sartorius

Gracilis

Popliteus

Gastrocnemius

Vastus lateralis

Vastus medialis

Vastus intermedius

Rectus femoris

Transverse Plane Medial Rotation Lateral Rotation
 

Popliteus

Semimembranosus

Semitendinosus

Sartorius

Gracilis

Biceps femoris

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KNEE MUSCLE ATTACHMENT
Muscle Proximal Attachment Distal Attachment
Rectus femoris AIIS and ilium superior to acetabulum Quadriceps tendon to patella and ultimately tibial tuberosity
Vastus lateralis Greater trochanter and lateral lip of linea aspera (femur) Quadriceps tendon to patella and ultimately tibial tuberosity
Vastus medialis Intertrochanteric line and medial lip of linea aspera (femur) Quadriceps tendon to patella and ultimately tibial tuberosity
Vastus intermedius Anterior and lateral surfaces of shaft of femur Quadriceps tendon to patella and ultimately tibial tuberosity
Sartorius ASIS and superior part of notch inferior to it Superior part of medial surface of tibia
Gracilis Body and inferior ramus of pubis Superior part of medial surface of tibia
Tensor faciae latae ASIS; anterior part of iliac crest Iliotibial (IT) band to lateral condyle of tibia
Semitendinosus Ischial tuberosity Medial surface of superior part of tibia
Semimembranosus Ischial tuberosity Posterior aspect of medial condyle of tibia; reflected attachment forms oblique popliteal ligament (to lateral femoral condyle)
Biceps femoris Long head: Ischial tuberosity Short head: Linea aspera and lateral supracondylar line of femur Lateral side of head of fibula
Gastrocnemius

Lateral head: Lateral aspect of lateral condyle of femur

Medial head: Popliteal surface of femur; superior to medial condyle

Posterior surface of calcaneus via calcaneal tendon
Popliteus Lateral surface of lateral condyle of femur and lateral meniscus Posterior surface of tibia, superior to soleal line

Introduction

The knee complex is one of the most often injured regions in the human body and the most frequently injured joint during sports activities.1 The myriad of ligamentous attachments, along with numerous muscles crossing the joint, provide insight into the joint’s complexity. This anatomical complexity allows for elaborate interplay between the simultaneous mobility and stability roles required by the knee complex. The knee joint works in conjunction with the hip, ankle, and joints in the feet to support the body’s weight during static erect posture. Dynamically, the knee complex is responsible for moving and supporting the body during a variety of both routine and difficult activities. The knee’s complex structure and multiple functions reflect its major roles in stability and mobility that are needed to complete many human movements.

The knee complex is composed of two distinct articulations located within a single joint capsule: the tibiofemoral joint and the patellofemoral joint. The tibiofemoral joint is the articulation between the distal femur and the proximal tibia. The patellofemoral joint is the articulation between the distal femur and the posterior patella. Although the ...

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