This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The muscles of the hip are numerous and their action is often intricate: many muscles are usually used to produce a single movement. Some muscles not only cross the hip-joint but another joint as well. Thus the psoas crosses the hip-joint and pelvis to reach the spine. The hamstring muscles, the rectus femoris, gracilis, and sartorius cross both the hip-joint and knee-joint, as does practically the tensor fasciae femoris through its prolongation, the iliotibial band. The movements of the hip are flexion, extension, adduction, abduction, and rotation. Circumduction is a combine ation of the first four movements.
Flexion is mainly the result of the action of the sartorius, iliacus, psoas, rectus femoris, and pectineus.
Extension is mainly due to the gluteus maximus, medius, and minimus, biceps, semitendinosus, and semimembranosus.
Abduction in the extended position is due to the tensor fasciae femoris, sartorius, gluteus medius, and gluteus minimus. When flexed the short rotators also aid.
Internal rotation is produced mainly by the tensor fasciae femoris and the anterior portion of the gluteus medius and minimus; three muscles only. The iliopsoas acts as a weak internal rotator if the femur is in a position of extreme external rotation.
External rotation is mainly due to the short external rotators - pyriformis, gemelli, obturators, quadratus femoris, the adductors, and the posterior portion of the three gluteals. To a slight extent the sartorius, iliopsoas, pectineus, and biceps may also aid at times.
The crest of the ilium can be palpated in its entire length. In very thin people it causes an elevation of the surface, but usually it is marked by a depression. Its anterior third is subcutaneous and is more easily seen and felt than the posterior two thirds. A line joining the highest point of the crests passes through the fourth lumbar spine. A line joining the anterior superior spines in front passes below the promontory of the sacrum. The anterior superior spine can be readily felt. It lies downward and outward from the umbilicus: as has been said, measurements are best taken by pressing the tape against its lower surface rather than its subcutaneous one.
The posterior superior spine, marked by a dimple, is best recognized by following the crest of the ilium to its posterior extremity. It is opposite the middle of the sacroiliac joint and the second sacral spine.
The posterior inferior spine is 4 to 5 cm. (1 1/2 to 2 in.) directly below the posterior superior spine. The spine of the ischium, which marks the position of the pudic and sciatic arteries, is 8 to 10 cm. (3 to 4 in.) below the posterior superior spine and the tuberosity of the ischium is 12 to 15 cm. (5 to
6 in.). Running forward from the posterior inferior spine for a distance of 4 to 5 cm. (1 1/2 to 2 in.) is the great sciatic notch; through it pass the pyriformis muscle, gluteal artery and nerves, and sciatic nerve. A line joining the posterior superior spine and the tip of the greater trochanter may be named the posterior iliotrochanteric line
(iliotrochanteric line of Farabeuf). It marks roughly the posterior edge of the gluteus medius muscle and goes through the upper edge of the gluteus maximus. The gluteal artery and superior gluteal nerves cross this line at the junction of the upper and middle thirds, this being about opposite the posterior inferior spine. A line joining the tuberosity of the ischium and tip of the greater trochanter may be called the ischiotrochanteric line: it is crossed at the junction of its inner and middle thirds by the sciatic nerve.
The greater trochanter is marked by an eminence in thin people and a depression in the plump and fat. Its anterior upper edge is crossed by the tendon of the gluteus medius and cannot be readily outlined. Its upper posterior extremity or tip is readily distinguished and is the spot used for measurements. This point is called the tip of the greater trochanter and must be searched for posteriorly. It is opposite the centre of the head of the femur and is on a level with the spine of the pubis.
The Roser-Nelaton line is one drawn from the anterior superior spine to the tuberosity of the ischium. It passes through the tip of the greater trochanter. It is of importance in fractures and dislocations (Fig. 507).
Bryant's triangle ("Bryant's Surgery", vol. ii, p. 412) is to be drawn while the patient is lying on his back. One side is a perpendicular let fall from the anterior superior spine to the table, the other side is one joining the anterior superior spine and the tip of the greater trochanter, the base is a line running horizontally from the tip of the greater trochanter to the perpendicular line (Fig. 507). If the tip of the trochanter becomes elevated, as in fractures of the neck of the femur, it shortens the base of the triangle on the affected side as compared with the base of the triangle on the sound side.
The anterior iliotrochanteric line may be designated as a line joining the anterior superior spine and the tip of the greater trochanter. In normal individuals it slopes downward and backward, forming an iliotrochanteric angle (b a c, Fig. 507) of about 30 degrees. In cases of fracture or luxation this angle becomes reduced as the shortening increases until the tip reaches the level of the anterior superior spine. A rough estimate of this angle by sight and palpation usually enables one to decide immediately as to the presence of shortening from fracture or luxation without the trouble of erecting Bryant's triangle. The anterior iliotrochanteric line forms the anterior side of Bryant's triangle and the anterior half of the Roser-Nelaton line.
The gluteal cleft separates the buttocks. In its lower portion can be felt the coccyx. The gluteal (gluteofemoral) fold is formed mainly by the subcutaneous fatty tissues and passes horizontally outward from the lower part of the gluteal cleft. A shortening of the leg on either side causes the corresponding fold to incline downward. It is marked in extension and gradually lessens on flexion and disappears when 90 degrees is reached. It is crossed obliquely downward and outward at about its middle by the lower edge of the gluteus maximus. Its disappearance in coxalgia is caused by the flexion incident to that affection.