GENERAL INFORMATION
The Vastus Intermedius is one of the four muscles comprising the quadriceps femoris group. It is located deep in the thigh, beneath the Rectus Femoris. It plays a pivotal role in extending the knee joint, essential for activities such as running, jumping, and climbing stairs. As one of the primary stabilisers of the knee, it is critical for both athletic performance and everyday mobility.
ORIGIN OF VASTUS INTERMEDIUS
The Vastus Intermedius muscle originates from the upper two-thirds of the anterior and lateral surfaces of the femur, lying directly on the femur’s body, which makes it less palpable than other quadriceps muscles.
INSERTION POINT
The Vastus Intermedius inserts into the base of the patella and ultimately into the tibial tuberosity via the patellar ligament. It shares a common tendon with other members of the quadriceps muscle group.
MAJOR ARTERIES OF VASTUS INTERMEDIUS
The Vastus Intermedius muscle receives blood supply from the lateral circumflex femoral artery and the profunda femoris artery, ensuring it is well-nourished for sustained physical activity.
NEURAL INNERVATION
Neural innervation is provided by the femoral nerve, specifically from the lumbar nerve root L4.
TRIGGER POINT OF VASTUS INTERMEDIUS
Trigger points in the Vastus Intermedius can cause pain deep in the thigh and may affect knee mobility. They often manifest during extensive use or due to injury.
CONCENTRIC FUNCTION
Concentrically, the Vastus Intermedius functions to extend the knee. This action is crucial for powering movements such as sprinting, kicking, and ascending steps.
ECCENTRIC FUNCTION
Eccentrically, it helps vastus intermedius in controlling the deceleration of knee flexion, such as when descending stairs or landing from a jump, protecting the knee joint from sudden impacts.
ISOMETRIC FUNCTION
Isometrically, the vastus intermedius muscle stabilises the knee in a fixed position, which is essential during tasks that require a steady posture, such as lifting heavy objects or maintaining balance on uneven surfaces.
RELATED MUSCLE-SCIENTIFIC NAMES
- Rectus Femoris: Crosses both the hip and knee joints, aiding in hip flexion and knee extension.
- Vastus Lateralis: Located on the outer side of the thigh, it is crucial for knee extension.
- Vastus Medialis: Found on the inner part of the thigh, it assists in knee extension and stabilises the patella.
- Sartorius: The longest muscle in the body, running from the hip to the knee, it flexes, abducts, and laterally rotates the thigh
ANTAGONIST
- Hamstrings: These include the biceps, femoris, semitendinosus, and semimembranosus, and they are responsible for knee flexion and hip extension.
- Gastrocnemius: Part of the calf muscle flexes the knee, and plantarflexes the ankle.
- Popliteus: Located at the back of the knee, it unlocks the knee joint and assists in knee flexion.
COMMON INJURIES
- Quadriceps tendinitis: Inflammation of the quadriceps tendon due to overuse.
- Patellar tracking problems: Misalignment of the patella during knee movement, causing pain and dysfunction.
- Muscle strains: Overstretching or tearing of muscle fibres, often due to sudden or forceful movements.
EXERCISES FOR VASTUS INTERMEDIUS
- Leg Extensions: Isolate and strengthen the Vastus Intermedius by extending the knee against resistance in a seated position.
- Squats: Engage the entire quadriceps group, emphasising knee extension and thigh muscle development.
- Lunges: Enhance muscle activation through dynamic movements that involve both knee extension and stabilisation.
- Leg Press: Focus on the quadriceps, including the Vastus Intermedius, by pushing weight away from the body using the legs.
STRETCHES FOR VASTUS INTERMEDIUS
- Quad Stretch: Stand and pull your heel towards your buttock, grasping the ankle with your hand to stretch the front of the thigh.
- Foam Rolling: Use a foam roller on the front of the thigh to release muscle tightness and improve blood flow.
- Dynamic Leg Swings: Perform front-to-back leg swings to gently stretch and warm up the quadriceps before engaging in more strenuous activities.
- Stair Stretch: Place the ball of the foot on a stair with the heel hanging off, and gently lower the heel to stretch the quadriceps and knee extensors.