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    Related Topics

    From Musculoskeletal System

    Zygomaticus
    Muscle that raises the corners of the mouth.
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Ischium
    Part of the pelvis that supports weight while sitting.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Facial Bones
    Bones forming the structure of the face.
    Hinge Joints
    e.g., elbow, knee
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.
    Ligamentum Flavum
    Spinal ligament connecting the laminae of adjacent vertebrae.
    Flexor Tendons
    Tendons that help flex the fingers and toes.
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Rectus Abdominis
    Abs muscle that flexes the trunk.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Pivot Joints
    e.g., atlanto-axial joint
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Saddle Joints
    e.g., thumb joint
    Tarsals (7 bones)
    7 ankle bones.
    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.

    Quadriceps

    Reviewed by our medical team

    Rectus Femoris, Vastus Medialis, Vastus Lateralis, Vastus Intermedius.

    1. Overview

    The quadriceps femoris, commonly referred to as the quadriceps or "quads," is a powerful muscle group located in the anterior thigh. It consists of four individual muscles that converge into a common tendon to insert on the patella. The quadriceps are essential for knee extension, stabilizing the patella, and facilitating walking, running, squatting, and jumping. They are among the largest and strongest muscles in the body.

    2. Location

    The quadriceps are located in the anterior compartment of the thigh:

    • Proximally: Originate from the pelvis and femur.

    • Distally: Insert via the quadriceps tendon into the patella, which continues as the patellar ligament to the tibial tuberosity.

    • Superficial to: The femur, femoral artery, and deep thigh musculature.

    3. Structure

    The quadriceps femoris muscle group consists of four muscles:

    • Rectus femoris:

      • Originates from the anterior inferior iliac spine (AIIS).

      • Only quadriceps muscle that crosses both the hip and knee joints.

    • Vastus lateralis:

      • Originates from the greater trochanter and lateral linea aspera of the femur.

      • Largest of the quadriceps muscles; positioned on the lateral thigh.

    • Vastus medialis:

      • Originates from the medial linea aspera and intertrochanteric line.

      • Helps stabilize the patella medially (via vastus medialis oblique fibers).

    • Vastus intermedius:

      • Lies deep to the rectus femoris and originates from the anterior and lateral surfaces of the femur shaft.

    All four muscles converge to form the quadriceps tendon, which attaches to the patella. The continuation of this tendon as the patellar ligament inserts on the tibial tuberosity.

    4. Function

    The quadriceps muscle group serves several critical mechanical functions:

    • Knee extension: Primary extensor of the knee joint, crucial for walking, running, jumping, and standing.

    • Hip flexion: Rectus femoris assists in flexing the hip due to its pelvic origin.

    • Patellar stabilization: Especially by the vastus medialis oblique (VMO), preventing lateral patellar dislocation.

    5. Physiological role(s)

    The quadriceps play broader physiological roles in posture, mobility, and energy expenditure:

    • Postural support: Maintain upright stance and help resist gravity during squatting or descending stairs.

    • Shock absorption: Absorb impact during foot strike and deceleration activities.

    • Core coordination: Work with hip and core muscles to stabilize the pelvis and lumbar spine during dynamic movement.

    • Circulation support: Contractions aid venous return from the lower limbs, especially during prolonged standing or exercise.

    6. Clinical Significance

    The quadriceps are involved in a range of injuries, conditions, and rehabilitative scenarios:

    • Quadriceps strain or tear:

      • Common in athletes, particularly during sudden acceleration or deceleration.

      • May range from minor strain to complete rupture.

    • Quadriceps tendon rupture:

      • Often caused by forceful contraction against resistance; requires surgical repair if complete.

    • Patellofemoral pain syndrome (runner’s knee):

      • Can result from imbalance between vastus medialis and lateralis, leading to improper patellar tracking.

    • Weakness or atrophy:

      • Common post-injury or post-surgery; impacts gait and stability. Rehab includes strengthening and neuromuscular re-education.

    • Osgood-Schlatter disease:

      • Adolescents may develop inflammation at the tibial tuberosity due to traction by the quadriceps tendon during growth spurts.

    • Injections and intramuscular therapies:

      • Vastus lateralis is a preferred site for IM injections, especially in infants and non-ambulatory patients.

    Did you know? Your hand has 5 metacarpal bones.