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Hip Muscles Anatomy

A variety of hip muscles surround the hip joint, and act to accelerate, decelerate, and stabilize the hip joint. About 21 muscles cross the hip, providing both tri-planar movement and stability between the femur and the acetabulum.

Abnormal performance of the hip muscles may alter the distribution of forces across the joint articular surfaces, potentially causing, or at least predisposing, degenerative changes in the articular cartilage, bone, and surrounding connective tissues.

See Also: Pelvic Anatomy

Iliopsoas Muscle

The iliopsoas muscle, formed by the iliacus and psoas major muscles, is the most powerful hip flexor muscle, while also functioning as a weak adductor and external rotator of the hip. The iliopsoas attaches to the hip joint capsule, thereby giving it some support.

Since the muscle spans both the axial and appendicular components of the skeleton, it also functions as a trunk flexor, and affords an important element to the vertical stability of the lumbar spine, especially when the hip is in full extension and passive tension is greatest in the muscle.

Theoretically, a sufficiently strong and isolated bilateral contraction of any hip flexor muscle will either rotate the femur toward the pelvis, the pelvis (and possibly the trunk) toward the femur, or both actions simultaneously.

See Also: Thomas Test
hip flexor - Iliopsoas Muscle
Iliopsoas Muscle

Gluteus Maximus

The gluteus maximus is the largest and most important hip extensor. It is also an important external rotator of the hip.

The larger, superficial portion of this muscle inserts at the proximal part of the ITB, while the deep portion inserts into the gluteal tuberosity of the femur.

The inferior gluteal nerve, which innervates the muscle, is located on the deep portion.

The gluteus maximus is normally active only when the hip is in flexion, as during stair climbing or cycling, or when extension of the hip is resisted.

Gluteus Medius Muscle

The gluteus medius is critical for balancing the pelvis in the frontal plane during one leg stance, which accounts for approximately 60% of the gait cycle. During one leg stance, approximately 3 times the body weight is transmitted to the hip joint with two-thirds of that being generated by the hip abductor mechanism. In addition to its role as a stabilizer, the gluteus medius also functions as a decelerator of hip adduction.

Because of its shape, the gluteus medius is known as the deltoid of the hip.

The muscle can be divided into two functional parts, an anterior portion and a posterior portion:

  • The anterior portion works to flex, abduct, and internally rotate the hip.
  • The posterior portion extends and externally rotates the hip.

On the deep surface of this muscle is located the superior gluteal nerve and the superior and inferior gluteal vessels.

hip extensors

Gluteus Minimus Muscle

The gluteus minimus, the major internal rotator of the femur, is a relatively thin muscle situated between the gluteus medius muscle and the external surface of the ilium.

It receives support from the TFL muscle, semitendinosus, semimembranosus, and gluteus medius muscles.

The gluteus minimus also abducts the thigh, as well as helping the gluteus medius with pelvic support.

Gluteus minimus and external rotators

Piriformis Muscle

The Piriformis Muscle is an external rotator of the hip at less than 60 degrees of hip flexion. At 90 degrees of hip flexion, the piriformis reverses its muscle action, becoming an internal rotator and abductor muscle of the hip.

Because of its close association with the sciatic nerve, the piriformis can be a common source of buttock and leg pain.

Piriformis muscle
Piriformis Muscle

Rectus Femoris Muscle

The rectus femoris muscle , one of the four quadriceps muscles, is a two-joint muscle that arises from two tendons: one, the anterior or straight, from the anterior inferior iliac spine (AIIS); the other, the posterior or reflected, from a groove above the brim of the acetabulum.

The rectus femoris combines movements of flexion at the hip and extension at the knee. It functions more effectively as a hip flexor when the knee is flexed, as when a person kicks a ball.

Hip-Flexors-muscles

Obturator Internus Muscle

The obturator internus is normally an external rotator of the hip and an internal rotator of the ilium but becomes an abductor muscle of the hip at 90 degrees of hip flexion.

Obturator Externus Muscle

The obturator externus, named for its location external to the pelvis, is an adductor and external rotator of the hip.

Gemelli Muscle

The superior and inferior gemelli muscles are considered extensions of the obturator internus tendon. The superior gemellus is the smaller of the two. Both the gemelli function as minor external rotators of the hip.

Quadratus Femoris Muscle

The quadratus femoris muscle, another external rotator of the hip, is a flat, quadrilateral muscle, located between the inferior gemellus and the superior aspect of the adductor magnus.

The quadratus femoris and the inferior gemellus share the same innervation (L4–L5). The obturator internus and superior gemellus also share the same innervation (L5–S1).

Hip External rotators
Hip External rotators

Pectineus Muscle

The pectineus is an adductor, flexor, and internal rotator of the hip. Like the iliopsoas, the pectineus attaches to and supports the joint capsule of the hip.

Tensor Fascia Latae Muscle

The TFL muscle envelops the muscles of the thigh. The TFL muscle counteracts the backward pull of the gluteus maximus on the iliotibial band (ITB). The TFL muscle also flexes, abducts, and externally rotates the hip. The trochanteric bursa is found deep to this muscle, as it passes over the greater trochanter. The attachment of the TFL muscle via the ITB to the anterolateral tibia provides a flexion moment in knee flexion and an extension moment in knee extension.

tfl muscle
TFL muscle

Sartorius Muscle

The sartorius muscle is the longest muscle in the body. The sartorius is responsible for flexion, abduction, and external rotation of the hip, and some degree of knee flexion.

Sartorius muscle
Sartorius muscle

Hamstrings Muscle

The hamstrings muscle group consists of the biceps femoris, the semimembranosus, and the semitendinosus.

Biceps Femoris:

The biceps femoris arises by way of a long and short head. Only the long head acts on the hip. The long head is active during conditions that require lower amounts of force, such as decelerating the limb at the end of the swing phase and during forceful hip extension.

The biceps femoris extends the hip, flexes the knee, and externally rotates the tibia. The biceps femoris (53%) is the most commonly strained muscle of the hamstring complex.

The anatomy of the biceps femoris may help to explain its higher rate of injury. Firstly, it has a long and a short head, both with separate nerve supplies. This dual innervation may lead to asynchronous stimulation of the two heads. Mistimed contraction of the different parts of the muscle group may mean a reduced capacity to generate effective tension to control the imposed loads of the muscle.

There may also be anatomical variations in the attachments of biceps femoris, which may predispose certain people to injury.

The long head of the biceps femoris originates from the lower part of the sacrotuberous ligament; therefore, it could be argued that the biceps femoris has a triarticular function and is, therefore, more predisposed to injury than the other hamstring muscles.

The insertion of the biceps femoris into the head of the fibula may also be a predisposing factor to injury. A previous knee or ankle injury resulting in alteration in the movement of the superior tibiofibular joint may affect the biomechanics of the biceps femoris, although this notion is speculative.

The biceps femoris acts as an external rotator of the semiflexed knee and the extended hip. Given the rotational demands of many sports, this function may also predispose the biceps femoris to injury.

Semimembranosus:

The semimembranosus gains its name from its membranous origin at the ischial tuberosity.

Semitendinosus:

The semitendinosus arises from the ischial tuberosity and inserts as part of the pes anserinus on the superior and medial aspect of the tibia, and deep fascia of the leg.

All three muscles of the hamstring complex (except for the short head of the biceps) work with the posterior adductor magnus and the gluteus maximus to extend the hip. The hamstrings also flex the knee and weakly adduct the hip.

The long head of the biceps femoris helps with external rotation of the thigh and leg; the more medial semimembranosus and semitendinosus muscles assist with internal rotation of the thigh and leg. When the hamstrings contract, their forces are exerted at both the hip and knee joints simultaneously; functionally, however, they can actively mobilize only one of the two joints at any one time.

Compared to walking and jogging, running is a stressful activity for the hamstrings and increases the high demands on their tendon attachments, especially during eccentric contractions.

During running, the hamstrings have three main functions:

  1. They decelerate knee extension at the end of the forward swing phase of the gait cycle. Through an eccentric contraction, the hamstrings decelerate the forward momentum (i.e., leg swing) at approximately 30 degrees short of full knee extension. This action helps provide dynamic stabilization to the weight-bearing knee.
  2. At foot strike, the hamstrings elongate to facilitate hip extension through an eccentric contraction, thus further stabilizing the leg for weight-bearing.
  3. The hamstrings assist the gastrocnemius in paradoxically extending the knee during the takeoff phase of the running cycle.
Hamstrings Muscle
Hamstrings Muscle

Hip Adductors Muscles

The adductors of the hip are found on the medial aspect of the joint.

Adductor Magnus:

The adductor magnus is the most powerful adductor, and it is active to varying degrees in all hip motions except abduction. The posterior portion of the adductor magnus is sometimes considered functionally as a hamstring because of its anatomic alignment. Because of its size, the adductor magnus is less likely to be injured than the other hip adductors.

Adductor Longus:

The adductor longus is the most prominent muscle of the adductors during resisted adduction, and forms the medial border of the femoral triangle. The adductor longus also assists with external rotation, in extension, and internal rotation in other positions. The adductor longus is the most commonly strained adductor muscle.

Gracilis:

The gracilis, the longest of the hip adductors, is also the most superficial and medial of the hip adductor muscles. The gracilis functions to adduct and flex the thigh and flex and internally rotate the leg. The other adductors of the hip include the adductor brevis, obturator externus, and the pectineus muscles. The main action of this muscle group is to adduct the thigh in the open kinetic chain and stabilize the lower extremity to perturbation in the closed kinetic chain. Each individual muscle can also provide assistance in femoral flexion and rotation.

hip adductor muscles
Hip Adductor Muscles
MuscleOriginInsertionInnervation
Adductor brevis External aspect of the body and inferior ramus of the pubisThe line from the greater trochanter of the linea aspera of the femurObturator nerve
Adductor longus In angle between pubic crest and symphysis The middle third of the linea aspera of the femurObturator nerve
Adductor magnusInferior ramus of pubis, ramus of ischium, and the inferolateral aspect of the ischial tuberosityTo the linea aspera and adductor tubercle of the femurObturator nerve and tibial portion of the sciatic nerve
Biceps femorisLong head arises from the sacrotuberous ligament and posterior aspect of the ischial tuberosity.
Short head does not act across the hip
On the lateral aspect of the head of the fibula, the lateral condyle of the tibial tuberosity, the lateral collateral ligament, and the deep fascia of the legTibial portion of the sciatic nerve, S1
Gemelli (superior and inferior)Superior–posterior (dorsal) surface of the spine of the ischium and inferior-upper part of the tuberosity of the ischiumSuperior- and inferior-medial surface of the greater trochanterSacral plexus
Gluteus maximus Posterior gluteal line of the ilium, iliac crest, aponeurosis of the erector spinae, posterior (dorsal) surface of the lower part of the sacrum, side of the coccyx, sacrotuberous ligament, and intermuscular fasciaIliotibial tract of the fascia latae and gluteal tuberosity of the femurInferior gluteal nerve
Gluteus medius Outer surface of the ilium between the iliac crest and the posterior gluteal line, anterior gluteal line, and fasciaLateral surface of the greater trochanterSuperior gluteal nerve
Gluteus minimus Outer surface of the ilium between the anterior and inferior gluteal lines, and the margin of the greater sciatic notchOn the anterior surface of the greater trochanterSuperior gluteal nerve
GracilisThe body and inferior ramus of the pubisThe superior medial surface of the proximal tibia, just proximal to the tendon of the semitendinosusObturator nerve
Iliacus MuscleSuperior two-thirds of the iliac fossa and upper surface of the lateral part of the sacrumFibers converge with tendon of the psoas major to lesser trochanterFemoral nerve
Obturator externusRami of the pubis, ramus of the ischium, and medial two-thirds of the outer surface of the obturator membraneTrochanteric fossa of the femurObturator nerve
Obturator internusInternal surface of the anterolateral wall of the pelvis and obturator membraneMedial surface of the greater trochanterSacral plexus
Pectineus Pectineal line Along a line extending from the lesser trochanter to the linea asperaFemoral or obturator or accessory obturator nerves
Piriformis Pelvic surface of the sacrum, gluteal surface of the ilium, capsule of the sacroiliac joint, and sacrotuberous ligamentUpper border of the greater trochanter of femurSacral plexus
Psoas majorTransverse processes of all the lumbar vertebrae bodies and intervertebral disks of the lumbar vertebraeLesser trochanter of the femurLumbar plexus
Quadratus femoris Ischial body next to the ischial tuberosityQuadrate tubercle on femurNerve to quadratus femoris
Rectus femoris By two heads, from the anterior–inferior iliac spine, and a reflected head from the groove above the acetabulumUpper border of the patellaFemoral nerve
SartoriusAnterior–superior iliac spine and notch below itUpper part of the medial surface of the tibia in front of the gracilisFemoral nerve
Semimembranosus Ischial tuberosityThe posterior-medial aspect of the medial condyle of the tibiaTibial nerve
SemitendinosusIschial tuberosityUpper part of the medial surface of the tibia behind the attachment of the sartonus and below that of the gracilisTibial nerve
Tensor fascia lataeAnterior part of outer lip of the iliac crest and the lateral surface of the anterior–superior iliac spineIliotibial tractSuperior gluteal nerve
Hip Muscles origins, insertions and innervation.

Muscles of the Hip by Action

Hip ActionPrime Movers Assistant Movers
Hip FlexorsIliopsoas
Sartorius
Tensor fascia latae
Rectus femoris
Pectineus
Adductor longus
Adductor brevis
Gracilis
Gluteus minimus (anterior fibers)
Hip ExtensorsGluteus maximus
Semitendinosus
Semimembranosus
Biceps femoris (long head)
Adductor Magnus (posterior head)
Gluteus medius (middle and posterior fibers)
Adductor magnus (anterior head)
Hip AbductorsGluteus medius (all fibers)
Gluteus minimus (all fibers)
Tensor fascia latae
Sartorius
Rectus femoris
Piriformis
Hip AdductorsAdductor magnus (anterior and posterior heads)
Adductor longus
Adductor brevis
Gracilis
Pectineus
Biceps femoris (long head)
Gluteus maximus (posterior fibers)
Quadratus lumborum
Obturator externus
Hip External rotatorsGluteus maximus
Gemellus inferior
Gemellus superior
Obturator internus
Quadratus femoris
Piriformis (at less than 60 degrees hip flexion)
Gluteus medius (posterior fibers)
Gluteus minimus (posterior fibers)
Biceps femoris (long head)
Sartorius
Obturator externus
Hip Internal rotatorsNot applicable Semitendinosus
Semimembranosus
Gracilis
Piriformis (at 90 degrees hip flexion)
Gluteus medius (anterior fibers)
Adductor longus
Adductor brevis
Pectineus
Adductor Magnus (posterior head)
Gluteus minimus (anterior fibers)
Tensor fascia latae

Notes

In a manner, generally, similar to the infraspinatus and teres minor at the glenohumeral joint, the short external rotators of the hip provide an important element of mechanical stability to the hip articulation Interestingly, the popular posterior surgical approach to a total hip arthroplasty (THA), used by some surgeons, necessarily cuts through at least part of the hip’s posterior capsule, potentially disrupting several of the short external rotators tendons. Studies have reported a significant reduction in the incidence of posterior hip dislocation when the surgeon carefully repairs the posterior capsule and external rotator tendons.

References

  1. Williams PL, Warwick R, Dyson M, et al: Gray’s Anatomy. 37th ed. London: Churchill Livingstone, 1989.
  2. Anderson LC: The anatomy and biomechanics of the hip joint. J Back Musculoskeletal Rehabil 4:145–153, 1994; and Neumann DA: Kinesiology of the hip: a focus on muscular actions. J Orthop Sports Phys Ther 40:82–94, 2010.
  3. Neumann DA. Kinesiology of the hip: a focus on muscular actions. J Orthop Sports Phys Ther. 2010 Feb;40(2):82-94. doi: 10.2519/jospt.2010.3025. PMID: 20118525.
  4. Delp SL, Hess WE, Hungerford DS, Jones LC. Variation of rotation moment arms with hip flexion. J Biomech. 1999 May;32(5):493-501. doi: 10.1016/s0021-9290(99)00032-9. PMID: 10327003.
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  6. Yoshio M, Murakami G, Sato T, et al: The function of the psoas major muscle: passive kinetics and morphological studies using donated cadavers. J Orthop Sci 7:199–207, 2002.
  7. Hall SJ: The Biomechanics of the Human Lower Extremity, Basic Biomechanics. 3rd ed. New York, NY: McGraw-Hill, 1999:234–281.
  8. Janda V: On the concept of postural muscles and posture in man. Aust J Physiother 29:83–84, 1983.
  9. Fagerson TL: Hip pathologies: diagnosis and intervention. In: Magee DJ, Zachazewski JE, Quillen WS, eds. Pathology and Intervention in Musculoskeletal Rehabilitation. St. Louis, MO: Saunders, 2009:497–527.
  10. Kapandji IA: The Physiology of the Joints, Lower Limb. New York, NY: Churchill Livingstone, 1991.
  11. Durrani Z, Winnie AP: Piriformis muscle syndrome: an underdiagnosed cause of sciatica. J Pain Symptom Manage 6:374–379, 1991
  12. Johnson CE, Basmajian JV, Dasher W: Electromyography of the sartorius muscle. Anat Rec 173:127–130, 1972.
  13. Anderson MA, Gieck JH, Perrin D, et al: The relationship among isokinetic, isotonic, and isokinetic concentric and eccentric quadriceps and hamstrings force and three components of athletic performance. J Orthop Sports Phys Ther 14:114–120, 1991
  14. Holmich P: Adductor related groin pain in athletes. Sports Med Arth Rev 5:285–291, 1998.
  15. Hasselman CT, Best TM, Garrett WE: When groin pain signals an adductor strain. Physician Sports Med 23:53–60, 1995.
  16. Lynch SA, Renstrom PA: Groin injuries in sport: treatment strategies. Sports Med 28:137–144, 1999.
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