1. Describe the Hip Joint under the following headings. a) Classification b) Movements c) Blood supply d) Ligaments.
The hip joint is the articulation between the hemispherical head of the femur and the cup-shaped acetabulum of the hip bone. The articular surfaces are covered with hyaline cartilage.
a) Classification: The hip joint is a synovial ball-and-socket joint.
b) Movements:
The following movements take place:
Flexion is performed by the iliopsoas, rectus femoris, and sartorius and also by the adductor muscles.
Extension (a backward movement of the flexed thigh) is performed by the gluteus maximus and the hamstring muscles.
Abduction is performed by the gluteus medius and minimus, assisted by the sartorius, tensor fasciae latae, and piriformis.
Adduction is performed by the adductor longus and brevis and the adductor fibers of the adductor magnus. These muscles are assisted by the pectineus and the gracilis.
Lateral rotation is performed by the piriformis, obturator internus and externus, superior and inferior gemelli, and quadratus femoris, assisted by the gluteus maximus.
Medial rotation is performed by the anterior fibers of the gluteus medius and gluteus minimus and the tensor fasciae latae.
Circumduction is a combination of the previous movements.
The extensor group of muscles is more powerful than the flexor group, and the lateral rotators are more powerful than the medial rotators.
c) Blood Supply:
The hip joint is supplied with blood from the medial circumflex femoral and lateral circumflex femoral arteries, which are both usually branches of the deep artery of the thigh (profunda femoris), but there are numerous variations and one or both may also arise directly from the femoral artery.
d) Ligaments:
The iliofemoral ligament is a strong, inverted Y-shaped ligament. Its base is attached to the anterior inferior iliac spine above; below, the two limbs of the Y are attached to the upper and lower parts of the intertrochanteric line of the femur. This strong ligament prevents overextension during standing. The pubofemoral ligament is triangular.
The base of the ligament is attached to the superior ramus of the pubis, and the apex is attached below to the lower part of the intertrochanteric line. This ligament limits extension and abduction.
The ischiofemoral ligament is spiral shaped and is attached to the body of the ischium near the acetabular margin. The fibers pass upward and laterally and are attached to the greater trochanter. This ligament limits extension.
The transverse acetabular ligament is formed by the acetabular labrum as it bridges the acetabular notch. The ligament converts the notch into a tunnel through which the blood vessels and nerves enter the joint. The ligament of the head of the femur is flat and triangular. It is attached by its apex to the pit on the head of the femur (fovea capitis) and by its base to the transverse ligament and the margins of the acetabular notch. It lies within the joint and is ensheathed by synovial membrane.
