Rectus Femoris Muscle

Authors
Affiliations

Doctor of Physical Therapy

B.S. in Kinesiology

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Hip and Thigh Muscles

Muscles of the Iliac and Anterior femoral regions2

Muscles of the Iliac and Anterior femoral regions

Cross-section of middle thigh2

Cross-section of middle thigh
Reading list
  • MMT
Muscle Origin Insertion Innervation Action
Rectus femoris AIIS
Acetabular roof
Tibial tuberosity via Patellar ligament Femoral n.
L2 - L4
Hip: Flexion
Knee: Extension

Origin

Note

The rectus femoris origin on the ASIS combines with the path of the ilio-femoral lig. strengthening the anterior aspect of the joint capsule.

Insertion

Tibial tuberosity (via patellar lig.)

Nerve

Femoral nerve (L2, L3, L4)

Action

  • Hip: Flexion
  • Knee: Extension

The rectus femoris can only generate 20% of the total force of the quadriceps group, but it cannot produce full knee extension in isolation.

The rectus femoris muscle is a 2-joint muscle, acting on both the hip and the knee. As a result, these two joints can impact the rectus femoris’ efficiency on the other. The hip joint can significantly impact the rectus femoris’ role in the knee extensor mechanism. In addition, the rectus femoris’ ability to efficiently flex the knee is proportional to the degree of hip flexion which we discuss more here.

Note

“The line of pull of the rectus femoris, with respect to the patella, is at an angle of about 5 degrees with the femoral shaft (see Fig. 20-12).”

Biomechanics

  • When in hip flexion, the ASIS and superior margin of the trochlea is shortened.
  • At hip neutral, the distance between the ASIS and superior margin of the trochlea increases.
  • In hip extension, the distance between the ASIs and superior margin of the trochlea is maximized.

As the lower extremity moves into hip flexion and knee extension, the rectus femoris continues to shorten, resulting in active insufficiency, demonstrated as a decrease in knee extension efficiency. This decrease in efficiency is countered through an increase in vastus lateralis and vastus medialis recruitment.

Force Couple

Erector Spinae and the Rectus Femoris are considered a force couple since both produce anterior pelvic tilt

Notes

“The rectus femoris attaches to the pelvis near the anterior-inferior iliac spine and immediately superior to the acetabulum. The vastus muscles, however, attach to an extensive part of the femur, particularly the anterior-lateral shaft and the linea aspera (see Fig. 12.5). Although the vastus lateralis has the largest cross-sectional area of the quadriceps muscles, the vastus medialis extends farther distally toward the knee.”

“The proximal part of the rectus femoris emerges between the limbs of an inverted V formed by the sartorius and tensor fasciae latae (see Fig. 12.26). This large bipennate­shaped muscle has its proximal attachments on the anterior­inferior iliac spine, along the superior rim of the acetabulum, and in the adjacent joint capsule. The relatively robust capsular attachment made by the “reflected” tendon of the rectus femoris has been described as an important stabilizer of the anterior capsule.238 Along with the other members of the quadriceps, the rectus femoris attaches to the tibia via the patellar tendon. The rectus femoris is responsible for about one­third of the total isometric flexion torque at the hip.144 In addition, the rectus femoris is a primary knee extensor. The combined two­joint actions of this important muscle are considered in Chapter 13. The anatomy and function of the pectineus and adductor longus are described in the section on the adductors of the hip.”

References

1.
Betts JG, Blaker W. Anatomy and Physiology. 2nd ed. OpenStax; 2022. https://openstax.org/details/books/anatomy-and-physiology-2e/?Book%20details
2.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
3.
Weinstock D. NeuroKinetic Therapy: An Innovative Approach to Manual Muscle Testing. North Atlantic Books; 2010.
4.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
5.
Jones B. B Project Foundations. b Project; 2025.
6.
Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.
7.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.

Citation

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