The Pelvic Girdle and Hip Joint 167to its being a common site of strain in the dancer. The sartorius also can act to produce flexion or
internal rotation of the knee, which will be further discussed in chapter 5.
Palpation: While standing on one leg, perform a front attitude (hip flexion and external rotation) with
the other leg and then carry this gesture leg to the side. Because the sartorius is the most superficial
of the anterior thigh muscles, it can be both seen and easily palpated below and slightly medial to the
ASIS. Note that as shown in figure 4.6, an inverted “V” is formed with the sartorius forming the medial
ray, the tensor fasciae latae composing the lateral arm, and the rectus femoris lying in between.Posterior Muscles of the Hip
The posterior muscles of the hip include the gluteus maximus, hamstrings, and deep outward rotators.
All three of these muscle groups cross posterior to the axis of the hip joint for flexion-extension, and the
gluteus maximus and hamstrings share the common action of hip extension, such as used in a back
parallel tendu or in jumping. The hip extensors are well suited for propulsive activity such as jumping
and running due to their large cross-sectional area and the power they can generate. However, their
ability to produce force is dramatically influenced by the degree of
hip flexion, with about twice as much extensor strength present with
90° of hip flexion versus a neutral position of extension (Hamill and
Knutzen, 1995). This principle is often utilized by leaning the trunk
forward when going up a hill or stairs or in the preparation for a
jump. Posturally, these muscles can also play the important role of
producing a posterior tilt of the pelvis and countering the tendency
for an anterior tilt of the pelvis or forward lean of the torso.
Although the deep outward rotators cross posterior to the flexion-
extension axis through the hip, they generally have a very horizontal
line of pull. This makes them better suited for effecting hip external
rotation and hip horizontal abduction than hip extension.Gluteus Maximus
The gluteus maximus (G. gloutos, buttock + maximus, largest),
shown in figure 4.7, is the largest and most superficial of the but-
tocks muscles. It forms the roundness of the back of the buttocks.
Its large size in humans is thought to be due to the demands of
upright stance and locomotion. The gluteus maximus is the most
powerful hip extensor and is crucial for movements requiring large
forces such as going up stairs, walking up hills, running, and
jumping. In addition to hip extension, the gluteus maximus can
produce hip external rotation, and the upper fibers can produce
hip abduction against resistance. Due to its insertion into the ilio-
tibial band or tract, a strong fascia of the lateral thigh that spans
between the pelvis and lower leg, the gluteus maximus indirectly
also helps support the femur upon the tibia.
Palpation: You can easily palpate the gluteus maximus by placing
your fingertips over the back of the buttocks while standing and
simply contracting or “setting” the muscle without any joint move-
ment necessary. To elicit a stronger contraction of the muscle, extend
and externally rotate the hip by lifting the leg in a back attitude.Attachments and Primary Actions of Gluteus Maximus
Muscle Proximal attachment(s) Distal attachment(s) Primary action(s)
Gluteus maximus
(GLOO-tee-us MAK-si-mus)Crest and posterior surface
of ilium, posterior surface
of sacrum and coccyxLine on posterior femur
between greater trochanter and
linea aspera and iliotibial tractHip extension
Hip external rotationFIGURE 4.7 The gluteus maximus
muscle and iliotibial band (right hip, pos-
terior view).