The hip joint is a ball-and-socket joint, formed by the femoral head and the acetabulum (Fig. 1, see Standring, Fig. 80.15). The articular surfaces are spherical with a marked congruity; this limits the range of movement but contributes to the considerable stability of the joint. In the anatomical position, the anterior/superior part of the femoral head is not covered by the acetabulum. This is because the axes of the femoral head and of the acetabulum are not in line with each other. The axis of the femoral head points superiorly, medially and anteriorly, while the axis of the acetabulum is directed inferiorly, laterally and anteriorly. The femoral head is ovoid or spheroid but not completely congruent with the reciprocal acetabulum. It is covered by articular cartilage except for a rough pit for the ligamentum teres, a flattened fibrous band, embedded in adipose tissue and lined by the synovial membrane (Figs 2, 3). The ligament connects the central part of the femoral head with the acetabular notch and its transverse acetabular ligament. The ligament is extra-articular and contains a tiny branch of the obturator artery partly responsible for the vascular supply of the femoral head. Anteriorly these are two ligaments: the fan-shaped iliofemoral ligament of Bertin situated craniolaterally; and the pubofemoral ligament, in a more caudomedial orientation. Together they resemble the letter Z (Fig. 4). Posteriorly the capsule is strengthened by the ischiofemoral ligament (see Standring, Fig. 81.3). These three ligaments are coiled round the femoral neck. Extension ‘winds up’ and tautens the ligaments, thus stabilizing the joint passively (Fig. 5a); flexion slackens them (Fig. 5b). Lateral rotation tightens the iliofemoral ligament and also the pubofemoral ligament. Medial rotation tightens the ischiofemoral ligament. Abduction tightens the pubofemoral and the ischiofemoral ligaments. Adduction tightens the lateral part of the iliofemoral ligament. Fig 4 Anterior ligaments: 1, iliofemoral, lateral part; 2, iliofemoral, medial part; 3, pubofemoral. The flexor muscles of the hip joint (Table 1) are anterior to the axis of flexion and extension. The iliopsoas is the most powerful of the flexors (Fig. 6). It originates at the lumbar vertebrae and the corresponding intervertebral discs of the last thoracic and all the lumbar vertebrae, the superior two-thirds of the bony iliac fossa and the iliolumbar and ventral sacroiliac ligaments. The insertion is to the lesser trochanter. Although its main function is flexion, it is also a weak adductor and lateral rotator. The distal part of the muscle is palpable just deep to the inguinal ligament, where it lies bordered by the sartorius muscle laterally and the femoral artery medially (Fig. 7). The tensor fasciae latae (see Fig. 7) originates at the outer surface of the anterior superior iliac spine, and inserts into the proximal part of the iliotibial tract – a strong band which thickens the fascia lata at its lateral aspect. Thus the course of the tensor is dorsal and distal. Acting through the iliotibial tract the muscle extends and rotates the knee laterally. It may also assist in flexion, abduction and medial rotation of the hip. In the erect posture, it helps to steady the pelvis on the head of the femur (Fig. 8). The muscle can be palpated easily during resisted flexion and abduction of the hip with the knee extended.
Applied anatomy of the hip and buttock
The hip joint
Capsule and ligaments
Muscles
Flexor muscles
anatomy of the hip and buttock
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