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    Related Topics

    From Musculoskeletal System

    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Cranial Bones
    Bones of the skull that protect the brain.
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Vomer Bone
    Bone forming the nasal septum.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.
    Latissimus Dorsi
    Back muscle responsible for arm adduction and extension.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Hinge Joints
    e.g., elbow, knee
    Sternum
    Breastbone located in the center of the chest.
    Skull
    Bony structure of the head that encases the brain.
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Adductors
    Muscles that bring the thighs toward the midline.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Carpals (8 bones)
    8 wrist bones.
    Masseter
    Muscle that elevates the mandible.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Nasal Bones
    Bones forming the bridge of the nose.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.

    Patellar Tendon

    Reviewed by our medical team

    Tendon connecting the patella to the tibia.

    1. Overview

    The patellar tendon (more accurately termed the patellar ligament) is a strong, flat band of connective tissue that connects the inferior pole of the patella (kneecap) to the tibial tuberosity. It plays a vital role in knee extension as part of the quadriceps mechanism. Though commonly called a tendon due to its association with the quadriceps muscle, it is technically a ligament because it connects bone (patella) to bone (tibia).

    2. Location

    The patellar tendon is located in the anterior aspect of the knee:

    • Proximally: Attached to the apex (inferior portion) of the patella.

    • Distally: Inserts onto the tibial tuberosity on the anterior surface of the proximal tibia.

    • Anteriorly: Lies superficial to the infrapatellar fat pad and anterior to the knee joint capsule.

    • Deep to: The skin and superficial fascia of the anterior knee.

    3. Structure

    The patellar tendon is a thick, fibrous band composed primarily of densely packed collagen fibers arranged in parallel:

    • Length: Typically ranges from 3 to 5 cm in adults.

    • Width: Approximately 2 to 3 cm; broader at the patellar end and narrower at the tibial insertion.

    • Histology: Composed of type I collagen, tenocytes, and a small amount of ground substance.

    • Surrounding structures: Covered by a thin paratenon and surrounded by fat pads (prepatellar and infrapatellar fat pads).

    4. Function

    The patellar tendon is an essential structure in the extension mechanism of the knee:

    • Transmits force: Transfers force from the quadriceps muscle (via the patella) to the tibia during knee extension.

    • Supports locomotion: Critical for walking, running, jumping, squatting, and standing from a seated position.

    • Acts as a pulley: Works with the patella to change the angle of force, increasing the mechanical efficiency of the quadriceps.

    5. Physiological role(s)

    Beyond movement, the patellar tendon supports several physiological and biomechanical roles:

    • Joint stabilization: Assists in maintaining proper alignment of the patella and tibia during dynamic motion.

    • Force distribution: Helps evenly distribute loads across the knee joint, reducing stress on cartilage and bone.

    • Reflex arc: Involved in the patellar reflex (knee-jerk reflex), an important neurological test of spinal cord integrity (L2–L4).

    • Protects underlying structures: Shields deeper components of the knee joint during anterior impacts.

    6. Clinical Significance

    The patellar tendon is frequently involved in musculoskeletal conditions, especially among athletes and active individuals:

    • Patellar tendinopathy (jumper’s knee):

      • Chronic overuse injury characterized by pain, inflammation, and degeneration of the tendon, commonly seen in jumping sports (e.g., basketball, volleyball).

    • Patellar tendon rupture:

      • A complete tear that results in loss of active knee extension; often occurs due to sudden, forceful contraction of the quadriceps.

      • Requires surgical repair and long-term rehabilitation.

    • Osgood-Schlatter disease:

      • Common in adolescents; involves traction stress on the tibial tuberosity at the insertion of the patellar tendon, causing pain and inflammation.

    • Patellar tendon graft:

      • Often used in anterior cruciate ligament (ACL) reconstruction surgeries as a reliable autograft source (bone-patellar tendon-bone graft).

    • Tendinitis vs. tendinosis:

      • “Tendinitis” refers to acute inflammation, while “tendinosis” indicates chronic degenerative changes—both affecting function and requiring different treatment approaches.

    Did you know? The sternum is connected to the ribs by cartilage.