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    From Musculoskeletal System

    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Mandible
    Lower jawbone that houses the teeth.
    Pivot Joints
    e.g., atlanto-axial joint
    Adductors
    Muscles that bring the thighs toward the midline.
    Temporalis
    Muscle involved in closing the jaw.
    Ilium
    Uppermost and largest part of the hip bone.
    Tarsals (7 bones)
    7 ankle bones.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Skull
    Bony structure of the head that encases the brain.
    Syndesmoses
    Fibrous joints where bones are connected by ligaments.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Temporal Bones
    Bones forming the lower sides of the skull and housing the ears.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Tibia
    Shin bone, the larger bone in the lower leg.
    Iliolumbar Ligament
    Ligament connecting the ilium and lumbar vertebrae.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Masseter
    Muscle that elevates the mandible.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Trapezius
    Muscle responsible for moving, rotating, and stabilizing the scapula.

    Quadriceps Tendon

    Reviewed by our medical team

    Tendon that connects the quadriceps to the patella.

    1. Overview

    The quadriceps tendon is a strong, fibrous connective tissue that connects the quadriceps femoris muscle group to the patella (kneecap). It serves as a critical link in the extensor mechanism of the knee, enabling leg extension. The tendon combines the muscular forces of the four quadriceps muscles and transmits them to the patella, which then passes the force to the tibia via the patellar ligament.

    2. Location

    The quadriceps tendon is located in the anterior aspect of the thigh and knee:

    • Proximally: Formed by the convergence of the four quadriceps muscles (rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius).

    • Distally: Inserts on the superior border (base) of the patella.

    • Superficial to: The femur and joint capsule of the knee.

    • Continues as: The patellar ligament, which extends from the apex of the patella to the tibial tuberosity.

    3. Structure

    The quadriceps tendon is composed of dense regular connective tissue rich in Type I collagen fibers:

    • Layers: Three-layered architecture corresponding to the quadriceps components:

      • Superficial layer: From rectus femoris.

      • Intermediate layer: From vastus medialis and vastus lateralis.

      • Deep layer: From vastus intermedius.

    • Length: Approximately 5–6 cm in adults.

    • Blood supply: From branches of the lateral circumflex femoral artery and genicular arteries.

    • Innervation: No motor innervation; contains sensory nerve endings for proprioception and pain.

    4. Function

    The quadriceps tendon plays a vital role in knee joint movement:

    • Transmits force: Carries contraction force from the quadriceps muscles to the patella during knee extension.

    • Stabilizes the patella: Helps maintain proper tracking of the patella in the trochlear groove of the femur.

    • Supports joint mechanics: Acts as part of the extensor mechanism with the quadriceps muscles and patellar ligament.

    5. Physiological role(s)

    In addition to mechanical functions, the quadriceps tendon supports various physiological processes:

    • Enables locomotion: Facilitates walking, running, jumping, and rising from a seated position.

    • Joint proprioception: Contains sensory receptors that contribute to knee joint awareness and coordination.

    • Energy transfer: Converts muscle contraction into skeletal movement through elastic recoil and tension transmission.

    • Load distribution: Spreads tensile forces evenly across the anterior knee to reduce joint stress.

    6. Clinical Significance

    The quadriceps tendon is vulnerable to certain injuries and conditions, especially in athletes and older adults:

    • Quadriceps tendon rupture:

      • Often results from sudden, forceful loading of a flexed knee (e.g., jumping or falling).

      • Leads to loss of active knee extension, swelling, a palpable gap above the patella, and functional impairment.

      • Requires surgical repair in complete ruptures followed by extensive rehabilitation.

    • Tendinopathy:

      • Chronic degeneration due to overuse or repetitive strain, especially in jumping athletes ("jumper’s knee").

      • Presents with anterior knee pain and tenderness above the patella.

    • Post-surgical considerations:

      • Following knee arthroplasty or ACL reconstruction, care is taken to preserve or rehabilitate the quadriceps tendon to restore full extension.

    • Quadriceps tendon graft:

      • Used as an autograft option in ACL reconstruction; provides a strong, thick tissue source with minimal morbidity.

    • Calcific tendinitis:

      • Rare condition where calcium deposits form in the tendon, causing pain and limited knee function.

    Did you know? The pelvic girdle consists of the ilium, ischium, and pubis.