Stable joint with large freedom of movement
The hip joints form the connection between the torso and the legs. As ball-and-socket joints, they facilitate a large range of movement. Their special structure enables us to bend, stretch, adduct, abduct and rotate our legs. It is these movements which essentially allow us to walk, run and sit down.
Joint made of bone and cartilage
The hip joint is made up of two bony sections: The femoral head: globular end of the femoral neck;
The acetabulum: cup-like cavity in the pelvis bone.
When in a healthy condition, both parts of the joint are surrounded by joint cartilage which acts as a lubricant in order to reduce friction between the two parts of the joint. It additionally helps absorb shock; it distributes and reduces the forces which act upon the hip joint.
Role of the joint capsule
The fixed joint capsule forms an envelope around the hip joint to seal it off from the surrounding tissue. This capsule produces synovial fluid which serves to ensure friction-free movement of the hip joint and also supplies the joint cartilage with essential nutrients.
Stability and movement thanks to ligaments and muscles
It is the bony structure which makes this joint so very stable: The femoral head rests relatively securely in the amply sized concave acetabulum. The hip joint is also reinforced by strong ligaments. The joint is surrounded by strong muscles which help protect it and allow the legs to be moved with great force.
