Gluteus maximus is the primary muscle responsible for lateral rotation, supported by six deep external rotators known as deep external rotators (piriformis, obturator internus and externus, gemelli and quadratus femoris). Let’s investigate their movements.
Most movements that involve hip rotation in sports or everyday life will combine multiple actions; for instance, martial arts sidekicks will require hip flexion or abduction alongside rotation.
The Rectus Femoris
The Rectus Femoris (latin for “straight Thigh Muscle”) runs along the front of your thigh before narrowing into a thick tendon that attaches to the upper border of your patella. Part of your quadriceps muscles, this muscle works both to extend knee and flex hip – it is especially active during actions that involve both movements; such as standing up from sitting position or climbing stairs.
Typically, muscles with forces directed either anterior to or posterior to a joint’s medial-lateral axis of rotation are classified as flexors; otherwise they are extensors. However, this convention doesn’t always hold; for example a strong contraction of the iliopsoas can combine hip flexion with internal rotation at the hip joint.
Figure 5 depicts this situation by depicting a superior view of the hip, showing several external and internal rotators with solid arrows indicating their lines of force. Muscles with greater potential to produce action will have longer moment arms while those with lower potentials will typically have much shorter moment arms.
The rectus femoris exemplifies this characteristic because of its two tendinous heads: direct from the anterior inferior iliac spine, and indirect from the superior acetabular ridge and hip joint capsule. These tendonous heads converge distally about 2 cm to form one tendon but still maintain distinct identities with only 10-20% fibers intermingling as illustrated on T1-weighted MRI images.
This muscular cross-over allows the rectus femoris to serve both functions effectively, being an external rotator of the hip as well as knee extensor. If it becomes overextended due to someone squatting when getting out of a chair or climbing stairs regularly, passive insufficiency may arise as its functional movements cannot be completed successfully; then its ability to flex or extend may become impaired and only produce weak extensor torque from then onward.
The Obturator Externus
The Obturator Externalus muscle is one of the short external rotators of the hip and part of a group known as Deep Six Lateral Rotators, providing additional control of hip rotation during flexion than was provided by quadriceps femoris, which predominantly controls abduction and extension movements. Studies have demonstrated its significance as one of six Short External Rotators of the Hip (SEROs). This muscle was previously thought to have less of an influence in controlling rotation; however recent evidence shows it to play an active role.
Obturator externus muscle fibres converge posteriorly and form a tendon that inserts into the trochanteric fossa at the medial aspect of greater trochanter on femur’s greater trochanter, often with a bursa between it and femoral capsule. Innervation for this muscle is provided via its posterior branch of obturator nerve (L3-4).
Studies of dissections have indicated that the obturator externus plays an essential role in stabilising the head of femur in its hip socket and acting as a suspension sling. Furthermore, research indicates it also protects deep branch of medial circumflex femoral artery from stretch or disruption.
Additionally, this muscle has also been demonstrated to exert a major impact on the sacroiliac joint (SI). It has been described as acting like two pliers by pulling sacral base posteriorly and ilium anteriorly against SI nutation.
Strengthen this muscle through various exercises, such as lateral rotation while sitting in a chair. Or stretch it by lying back with right knee bent and pulling towards body with right leg pulled towards center.
Like its fellow muscles in this group, lateral rotation of the hip is an integral component of walking and running as well as providing hip stability in single leg stance. Furthermore, this movement plays an integral part in many martial arts moves such as sidekick which requires flexion as well as lateral rotation to perform properly. Furthermore, this form of strengthening can also be utilized during other activities like climbing stairs and lunging forward.
The Iliotibial Band
The Iliotibial Band (ITB), commonly referred to as Bandelette of Maissiat, is a thick strip of connective tissue running along the lateral side of your leg from your hip to knee. Although not technically considered muscle, this deep fascia of your thigh works alongside muscles (primarily Tensor Fasciae Latae ) to flex, abduct, and rotate both your hip and knee joint. ITBs play an essential role in providing lateral knee stability; they may play an instrumental part in contributing towards developing Iliotibial Band Syndrome which affects up to 25% adults!
Muscles that produce external hip rotation tend to have their lines of force pass posterior-lateral to the joint’s longitudinal axis of rotation, as seen in FIGURE 5. These muscles include gluteus maximus and 5 of 6 short external rotators (pectineus, obturator internus and externus, both gemelli), with quadratus femoris being an exception. Conversely, those producing internal rotation typically exhibit their force via anterior medial lines that pass anterior-medial to this axis of rotation; primary internal rotators include gluteus medius/minimus as well as adductor magnus longus/brevis/magnus/magnus/magnus/magnus/magnus/magnus longus/brevis/magnus adductor magnus longus/brevis/magnus/magnus/magnus being their primary internal rotators/rotators muscles/rotators lines passing anterior medial to this longitudinal axis of rotation whereas muscles performing internal hip rotation/rotators lines pass anterior medial to this joint’s longitudinal axis of rotation/quadratus femoris and not quadratus femoris (but see figure 5). FIGURE 5. FIGURE 5.This group includes gluteus medius/minimus/ adductor magnus longus/brevis/magnus
Dostal et al16,17 have conducted a new study that details various key factors that help determine how much and what kind of rotational forces a muscle can generate, such as its architecture defined by how fibers align relative to its force-generating axes.
This study has shown that, for short lateral rotators of the hip, iliotibial bands exert disproportionately large influences on external rotational torque when hip flexion reaches 90deg angle relative to their contribution during neutral hip flexion. This discovery helps explain how such muscles can produce high levels of external rotational torque even though their size remains relatively modest.
Study results demonstrated that skeletal muscle architecture could serve as an invaluable tool in evaluating hip muscles and predicting their function. While Dostal et al16,17’s work represents an essential beginning step, additional published work should focus on characterizing hip muscle morphology across a wider variety of movement patterns as well as considering body size differences and gender variances.
The Deep Six Lateral Rotators
The deep six lateral rotators are a group of six small muscles located underneath the gluteus maximus that all externally rotate the femur at the hip joint. They create an internal fan of muscle on the back side of pelvis that connects top of sacrum to greater trochanter of femur, providing stability as we move. Although not used for heavy movements, these muscles play an essential role in walking, running and other forms of pelvis rotational movements; furthermore they maintain alignment of knee and foot during gait cycles as well. Weakness in these muscles could result in compensations during movement as well as increased risk of injury.
This study’s objective was to measure the mass, sarcomere length, fascicle length and fascicle width of six muscles within this study’s focus area, in order to produce a high-quality muscle architecture data set that could be added into existing software models of the hip (such as OpenSim). Each of the six muscles has unique architecture which allows it to generate large amounts of hip external rotation throughout range of motion; with PI, OI and OE possessing greater force generating capabilities while SG and IG possess smaller capabilities in both regards.
These muscles arise in various locations on the pelvis; specifically the piriformis muscle from the anterior sacrum, quadratus femoris from the ischial spine, obturator internus and externus muscles from obturator fossa, tubercle, and fossa fossa; they then all connect to greater trochanter of iliotibial band on femur.
These muscles have names which describe their location; piriformis in Latin for “femur rump”, obturator externus outside the thigh bone and quadratus femoris are all names which refer to its shape (square). All three run laterally across the pelvis and insert onto greater trochanter of femur. What’s fascinating is their similar normalized fascicle lengths between males and females which suggests muscle architecture may play a greater role than differences in height when considering differences in body height between genders in these muscles.
FAQ
What are the primary muscles responsible for lateral rotation of the hip?
The gluteus maximus is the primary muscle responsible for lateral rotation, supported by six deep external rotators known as deep external rotators (piriformis, obturator internus and externus, gemelli, and quadratus femoris).
What movements involve the Rectus Femoris muscle?
The Rectus Femoris muscle works to extend the knee and flex the hip. It is especially active during actions that involve both movements, such as standing up from a sitting position or climbing stairs.
How is the Obturator Externus muscle significant?
The Obturator Externus muscle is one of the short external rotators of the hip and plays a crucial role in stabilizing the head of the femur in its hip socket. It also protects the deep branch of the medial circumflex femoral artery from stretch or disruption.
What is the role of the Iliotibial Band (ITB)?
The ITB, although not technically considered a muscle, works alongside muscles to flex, abduct, and rotate both the hip and knee joint. It plays an essential role in providing lateral knee stability and may contribute to developing Iliotibial Band Syndrome.
What are the Deep Six Lateral Rotators?
The deep six lateral rotators are a group of six small muscles located underneath the gluteus maximus that all externally rotate the femur at the hip joint. They play an essential role in walking, running, and maintaining alignment of the knee and foot during gait cycles.
