REIDER PART 205

Chapter 5_Pelvis, Hip, and Thigh 165

insert into the superior pole of the patella and, ultimatcly, through the patellar tendon, into the tibial tubercle. The rectus femoris muscle arises partly from the ATIS and partly from the anterior hip capsule and constitutes the central bulge of the thigh. The other three components of the quadriceps all arise below the hip joint. The vastus intermedius is located deep to the rectus femoris and is not separately visible. Flanking the medial border of the rectus femoris lies the vastus medialis, and the vastus lateralis fills out the lateral contour of the anterior thigh. In a lean or muscular individual, these muscle bellies may be clearly distinguishable. The lateral border of the thigh has a straight contour that is created by the iliotibial tract, which borders the vastus lateralis muscle. In the distal third of the thigh, the iliotibial tract narrows down and angles toward its insertion on the tubercle of Gerdy.

The adductor longus and gracilis muscles comprise the medial contour of the thigh. The adductor longus originates from the pubis and inserts on the linea aspera of the femur. The gracilis also arises from the pubis and runs the length of the medial thigh until it inserts as a narrow tendon on the tibia as part of the pes anserinus.

LateralAspect

Pelvis and Hip. Viewed from the lateral position, the most prominent landmark of the pelvis is the arching contour of the iliac crest (Fig. 5-3). The position of the pelvis is traditionally judged by the orientation of Nelatons linę, an imaginary linę drawn from the posterior superior iliac spine (PSIS) to the ASIS. In the standing patient, the ASIS is normally somewhat lower than the PSIS, giving Nelaton’s linę a downward slant.

From the lateral perspective, the examiner is looking directly at the prominence created by the principal abductor of the hip, the gluteus medius. The gluteus medius arises from the superior portion of most of the iliac wing and inserts on the greater trochanter. Anterior to the gluteus medius, the tensor fascia lata arises from the most anterior portion of the iliac crest and constitutes the anterior border of the lateral aspect of the hip. Posterior to the gluteus medius, the bulky gluteus max-imus muscle arises from the posterior ilium and adjacent sacrum. The belly of the gluteus maximus constitutes the familiar rounded contour of the buttock.

Thigh. Distal to the pelvic area, the vastus lateralis and the biceps femoris muscles constitute the anterior and the posterior contours of the thigh, respectively (Fig. 5-4). The most prominent bony landmark is the greater trochanter of the proximal femur. The greater trochanter projects laterally to provide inereased leverage for the gluteus medius and the gluteus minimus muscles that insert there. These critical muscles not only abduct the femur but also, morę importantly, prevent drooping of the pelvis when the opposite limb is lifted from the ground during normal ambulation. The contour of the greater trochanter is somewhat obscured by the overlying fascia lata, although the prominence it creates is still usually quite noticeable. It should lie just distal to the midpoint of Nelatons linę. Betwecn the fascia lata and the greater trochanter lies the trochanteric bursa, which facilitates the back-and-forth motion of the fascia lata across the greater trochanter during normal gait. Pain that localizes to the vicinity of the greater trochanter usually arises from trochanteric bursitis or gluteus medius tendinitis, rather than pathology of the hip joint itself.

Posterior Aspect

Pelvis and Hip. The posterior aspect of the pclvis is again dominated by the curve of the iliac crest (Fig. 5-5). The posterior border of the crest is seen to curve poster i-orły and medially to its point of termination, the PSIS. Relatively little soft tissuc ovcrlies the PSIS; conseąuently, its presence is often indicated by a dimple in the overly-ing skin. The PSIS overhangs the sacroiliac joint, which is located just distal to it. The sacroiliac joint is not normally visible, although it can be palpated as a longitudi-nal prominence proceeding distally from the PSIS. The other landmarks of the posterior hip and pelvis are mostly obscured by the great bulk of the gluteus max-imus, the principal extensor of the hip, which originates from the posterior portion of the iliac crest and inserts into both the fascia lata and the linea aspera of the posterior femur. The area of the sacrum is visible as a triangu-lar depression betwecn the two great prominences created by the gluteus maximus muscles. The sacrum tapers distally to the coccyx, which is palpable beneath the top of the midline crease of the buttocks.

The ischium is the most inferior of the three bones that constitute the innominate, or pelvic, bonę. Its inferior contour, the ischial tuberosity, constitutes the inferi-ormost portion of the pelvis. The ischial tuberosity is not normally visible, but it is palpable in the inferior medial buttock deep to the gluteus maximus. It serves as the ori-gin for the hamstrings, the principal flexors of the knee, and a portion of the adductor magnus.

Although the gluteus maximus obscures the deeper muscles of the posterior hip, their position can be esti-mated through knowledge of their relationship to the greater trochanter, whose prominence can usually be identified from the posterior perspective. A group of four short external rotators arises from the pelvis and inserts in a relatively smali area on the superior portion of the greater trochanter. From superior to inferior they are the piri-formis, the superior gemellus, the obturator internus, and the inferior gemellus. Tendinitis in these structures can be a source of posterior hip pain, and the piriformis is thought to sometimes compress the sciatic nerve, which emerges from beneath it. Two other transversely oriented muscles, the obturator externus and the quadratus femoris, insert further distally on the posterior margin of the greater trochanter. They are less likely than the external rotators to be implicated as a source of hip pain.

The transverse crease that forms at the junction of the buttock and the posterior thigh is known as the glutcal