Knee Anatomy

BONES OF THE KNEE:

The femur (thigh bone), tibia (shin bone), patella (knee cap), fibula (smaller bone next to shin bone).

Muscles, tendons and ligaments connect the knee bones. The kneecap glides in a groove in the thighbone and adds leverage to the thigh muscles, which are used to extend the leg. The thigh bone and shine bone come together at the knee joint and move on one another when bending or straightening the leg.

KNEE JOINT CAPSULE (not shown):

The knee joint capsule is a sac that encloses the knee joint cavity. It is attached to the bones of the joint, and forms the joint cavity. The knee joint capsule has a tough, fibrous outer membrane and an inner synovial membrane, which produces joint fluid (synovial fluid) that lubricates the joint and nourishes the articular cartilage that coats the ends of the bones in the joint.

LIGAMENTS OF THE KNEE:

Four main ligaments connect the bones of the knee:

Two ligaments are in the center of knee and are bathed in joint fluid - the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL)

The other two ligaments are located on the outside of the knee joint - the medial collateral ligament (MCL) on the inner side and the lateral collateral ligament (LCL) on the outer side.

Ligaments on outside of kneecap usually heal by themselves. Ligaments in the center of the knee rarely heal on their own because they are bathed in joint fluid and lack a blood supply.

CARTILAGE OF THE KNEE:
Connective tissue that absorbs shock. The two types of cartilage are: Articular & Meniscular.

Articular Cartilage:
Coating on the end of all bones that make up the knee joint. The back surface of kneecap, end of femur, and top of tibia are all covered with articular cartilage.

Damage to the articular cartilage is usually diffuse damage. This is usually gradual 'wear and tear' damage caused by overuse, aging, and can be accelerated by poor knee tracking.

Meniscus (Meniscal Cartilage):
Protects the articular cartilage and separates the bones of the knee. It is a spongy shock absorber. This is the cartilage referred to when you hear "torn cartilage; The meniscus is commonly torn in twisting injuries.

MUSCLES OF THE KNEE:
Quadriceps: Muscles on the front of the thigh. Used to straighten the knee

Hamstrings: Muscles on the back of thigh attach to tibia (shin bone) at back of knee. Used to bend the knee.

TENDONS OF THE KNEE:
Tendons join muscle to bone. The quadriceps tendon hooks quad muscles to the patella (kneecap); patella tendon connects the patella to the shinbone. The quadriceps tendon and patellar tendon actually connect to form one continuous tendon that covers the patella.

BURSAE: Small sacs that provide a lubricating surface between surfaces that needs to move.

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