Vastus Intermedius
The vastus intermedius muscle is one of the muscles of the quadriceps femoris group. It is often called the “invisible quadriceps” because it’s entirely hidden under the Rectus Femoris. Although it is small and hidden beneath other muscles of the quadriceps, it plays a crucial role in the function of the knee joint.
Anatomy:
The vastus intermedialis muscle is located in the anterior aspect of the thigh, just below the Rectus femoris, between the vastus lateralis and vastus medialis.
Proximal attachment:
Proximally, it attaches to the
- Lateral lip of the linea aspera
- Anterolateral surface of the shaft of the femur
Distal attachment:
Distally, it merges with other quadriceps muscles to form the quadriceps tendon and attaches to the base of the patella. Then, it continues as the patellar tendon to get attached to the tibial tuberosity.
Nerve innervation:
The vastus intermedius is innervated by the Femoral nerve(L2, L3, L4).
Blood supply:
Arterial supply: Femoral artery
Venous drainage: Femoral vein
Function
Concentric contraction (shortening):
Standard mover action:(distal attachment moving towards proximal)
When the vastus intermedius shortens while the femur is fixed, it extends the leg at the knee joint (straightens the knee)
Reverse mover action: (proximal segment moving towards distal)
When the tibia is fixed and the femur is moving, the concentric contraction of the vastus intermedius will extend the thigh at the knee joint. Example: standing up from a chair.
Eccentric contraction (lengthening):
When the vastus intermedius contracts eccentrically, it slows down and controls the knee flexion.
Isometric contraction:
The isometric contraction of the vastus intermedius will stabilize the patella and the knee joint.
Purpose:
The main purpose of the vastus intermedius is to work with other muscles of the quadriceps group to produce extension of the knee joint.
Other purposes of the vastus intermedius include,
Stabilization of the patella:
Through its attachment to the patella and tibial tuberosity, it stabilizes the patellofemoral and tibiofemoral joints.
Shock absorption:
During activities like walking, running, and jumping, the vastus intermedius, along with other quadriceps muscles, will help in shock absorption.
Especially during the landing phase or while the foot strikes the ground, eccentric contraction of the quadriceps muscles absorbs the impact and reduces excessive loading of the knee joint.
This stresses the importance of quadriceps muscles strengthening for the prevention of knee injuries.
Azarudheen is a passionate physiotherapist and exercise prescriptor with a deeply rooted belief in the transformative power of movement and education. His journey began in 2013 as a first-year physiotherapy student, balancing academics with part-time work to support his ambitions. Early in his career, he sought practical experience and began working at a fitness center, eventually transitioning into roles that expanded his knowledge and skill set in both clinical practice and teaching.
Driven by a relentless curiosity and desire for growth, Azarudheen took on an anatomy tutor position, believing in the value of continuous learning. A pivotal turning point came with his experience in cardiopulmonary rehabilitation at PSG Hospitals, where he worked closely with lung transplant patients. This experience emphasized the life-changing impact of functional movement and patient education, inspiring him to dive deeper into respiratory and cardiovascular physiology.
With strong support and belief in his vision, Azarudheen pursued a Master’s in Exercise and Sports Science at Manipal University—choosing it over conventional MPT programs to focus more on biomechanics, exercise physiology, strength and conditioning, and lifestyle health. His dedication was evident as he spent late nights at the library, worked part-time in gyms and cricket academies, and honed his craft through practical application.
In 2022, despite initial doubts, he opened his first clinic in his hometown—an act of courage and self-belief supported by his family and mentors. Built from the ground up, this clinic marked the start of a new era. Today, Azarudheen leads a growing team of 21 physiotherapists across two thriving clinics in Chennai and Coimbatore. His philosophy centers on patient education, movement optimization, and professional growth, and he continues to evolve both as a clinician and a leader.
Azarudheen’s journey reflects the power of perseverance, vision, and lifelong learning. He is not only a practitioner but also a mentor and advocate for a more thoughtful, movement-centered approach to healthcare.