Features of the Hip Joint

The hip joint is one of the most versatile in the human body. The joint's ball-and-socket construction allows for backward, forward and side-to-side movement as well as left/right rotation. This joint provides both mobility and stability in its function as a shock absorber for the upper body and torso.

Bones

• Bones make up the foundational structure of the hip joint. The femur, which is the longest bone in the body and is also referred to as the thigh bone, attaches at the pelvis to form the hip joint. The pelvis has two depressions, shaped like cups, called the acetabulum. The rounded head of the femur is the ball of the joint, fitting tightly into the the acetabulum, which is the socket. The surfaces of both are covered in a thin layer of cartilage, which smooths the movement of the joint.

Ligaments

• Ligaments (fibrous tissue that helps to connect joints and bones) are a very important part of the hip joint. Their placement ensures that the hip doesn't move out of its prescribed range of motion, which would cause great injury. There are three main ligaments. The iliofemoral ligament connects the pelvis to the femur at the front of the joint and is Y-shaped. It also limits hyperextension. The pubofemoral ligament attaches the pubis (in the groin area) to the femur. The ischiofemoral ligament provides reinforcement from the back, attaching the ischium to the two protrusions (known as trochanters) at the top of the femur.

Muscles

• The muscles of the hip joint provide the ability to raise and lower the legs and stabilize the actions of standing, walking and running. The system is complex, involving several different groups of muscles that all work together to provide the functionality of your hip. The muscle groups involved are the gluteals (attached to the back side of the pelvis), quadriceps (attached to the tibia and shin), iliopsoas (the hip flexor), hamstrings (hip extenders) and groin (attached to the pubis and extending down the thigh).