Functional Anatomy of the Hip-Muscles and Fascia

Original Editor - Ewa Jaraczewska

Top Contributors - Ewa Jaraczewska, Jess Bell, Kim Jackson and Lucinda hampton

Description

One theory assumes that the human body has two muscular systems: local and global. The local muscular system acts close to the joint axis, provides joint compression, and is responsible for this joint stability. Large forces produced by the muscles and small changes in their length create joint compression thus producing active stabilisation of the joint.The global system contains superficial muscles generating greater torque and greater moment arm.However it is the muscle architecture and the line of action that determines the muscles' primary role.

Daily activities require the hip joint to withstand high forces which is possible due to the contribution of the individual muscles surrounding the joint. Active stability provided by the hip muscles can increase passive stability in the normal hip as well as the hip with structural abnormality.

Muscles

External Rotators of the Hip

External Rotators

Attachements:

Quadratus femoris: ischial tuberosity to the intertrochanteric crest of the femur

Obturator internus and externus : obturator membrane and ischiopubic rams to greater trochanter (internus) or intertrochanteric fossa of the femur (externus)

Gemelli (superior and inferior): ischial spine(superior) or ischial tuberosity (inferior) to greater trochanter and obturator internus tendon

Piriformis: anterior surface of the sacrum and sacrotuberous ligament to the greater trochanter

Function:

• Active stabilisers of the hip joint. The primary role includes femoral head stabilisation in the acetabulum.
• When deep external rotators are resected during hip arthroplasty with a posterior surgical approach there is an increased rate of prosthetic dislocation and functional deficits. With capsular repairs, the dislocation rate is lower.
• Resisted external rotation of the hip with extension activates piriformis, but its line of force is not conducive to enhance joint compression.

Internal Rotators

Attachements:

Tensor Fascia Latae

Tensor Fascia Latae (TFL): the anterior superior iliac spine to iliotibial track, between the deep and superficial layers of the ITB

Gluteus medius

Gluteus minimus

Function:

• TFL works in different movement planes: assist with hip abduction in the frontal plane, performs hip flexion in the sagittal plane, completes an internal rotation in a transverse plane together with anterior gluteus medium and gluteus minimus
• Gluteus medius and Gluteus minimus are primary abductors and assist with internal rotation

Hip Abductor

Abductors

Attachements:

Gluteus minimus: the outer surface of the ilium, between the anterior and posterior gluteal lines to the greater trochanter.

Gluteus medius: the outer surface of the ilium, between the iliac crest, and the anterior and posterior gluteal lines to the greater trochanter. The muscle has three segments; anterior, posterior, middle or superficial, each with a specific orientation of the muscle fibres.

Tensor Fascia Latae

Piriformis

Function:

Gluteus minimus function include:

• Stabilisation of the hip and pelvis through modulation of the joint capsule
• Stabilisation of the femoral head in the acetabulum
• Rotation and flexion of the hip
• Prevention of anterior dislocation and migration of the femoral head in a superior and medial direction
• Proprioceptive role.

Gluteus medius is:

• Primary abductor of the hip

• Stabiliser of the pelvis and hip
• Preventing the pelvis from adduction in single-leg stance.
• Important stabiliser of the pelvis on the hip by contracting prior to and after foot contact regardless of the walking speed.

Piriformis:

• Externally (laterally) rotates the femur during the hip extension and abducts the femur during hip flexion.
• Acts as an auxiliary muscle and shows coactivation during pelvic floor muscles contracture.

Hip Adductors

Adductors

Attachements:

Adductor longus: pubic bone between the crest and symphysis to linea aspera of the femur

Adductor brevis: body and inferior ramus of the pubis to linea aspera of the femur

Adductor magnus: ischial tuberosity and inferior ramus of the pubis to linea aspera and the adductor tubercle

Gracilis: inferior pubic ramus to medial side of the tibial tuberosity

Pectineus: pectineal line of the pubis and pubic tubercle to pectineal line of the femur

Function:

• Hip adductors contribute to static balance performance
• Adductor longus provides some medial rotation
• Adductor Magnus extends the hip through his attachment on the ischial tuberosity
• In open chain activation, the primary function is hip adduction
• In closed chain activation, hip adductors help to stabilise the pelvis and lower extremity during the stance phase of gait.
• Secondary roles of hip adductors include hip flexion and rotation
• Gracilis and semitendinosus create the conjoined tendons known as the pes anserinus.

Hip Flexors

Flexors

Attachements

Iliopsoas has three portions:

Iliacus: lateral edge of the sacrum and iliac fossa to lesser trochanter of the femur

Psoas major: transverse processes of vertebrae T12–L5 to lesser trochanter of the femur

Psoas minor: vertebral bodies of T12–L1 to iliopubic ramus

Rectus femoris: anterior-inferior iliac spine, a superior rim of the femoral acetabulum to the base of the patella

Hip Flexors

Sartorius: anterior superior iliac spine to the upper medial side of the tibia

Tensor Fascia Latae

Function:

• Psoas major and Iliacus are separately innervated. They are active throughout hip flexion
• Iliacus and both Psoas muscles have a role similar to that of the rotator cuff muscles at the shoulder. They affect hip joint stability by creating tension in musculotendinous units as they pass over the anterior aspect of the hip joint
• Sartorius serves as both a hip and knee flexor and hip external rotator.

Hip Extensors

Extensors

Attachements:

Gluteus maximus: ilium, sacrum, coccyx, and the sacrotuberous ligament to gluteal tuberosity of the femur and iliotibial band.

Biceps Femoris:

Long head: ischial tuberosity to lateral tibial condyle and head of the fibula.

Short head: upper supra-condylar line and linea aspera to lateral tibial condyle and head of the fibula.

Semimembranosus: ischial tuberosity to superior and medial surface of the tibia

Semitendinosus: ischial tuberosity to the medial condyle of the tibia

Function:

• Gluteus maximus is one of the primary hip extensors and the strongest and biggest muscle in the body
• Gluteus maximus is prone to weakness and inhibition
• The biceps femoris long head is the most affected muscle in the hamstring strain injury.

Inversion of muscular action

The muscles of the hip joint can contribute to movement in several different planes depending on the position of the hip, which is caused by a change in the relationship between a muscle’s line of action and the hip’s axis of rotation manifests as a muscle’s secondary function.

For example, the gluteus medius and minimus act as abductors when the hip is extended and as internal rotators when the hip is flexed. The adductor longus acts as a flexor at 50° of hip flexion, but as an extensor at 70.

Fascia

The concept of fascia lines further explain the connection between adjacent structures: muscles, tendons, ligaments. This is called a myofascial continuity and it explains unique strains and connections that can occur following the injury, adhesions, postural changes.

The following are the fascial lines and the hip joint muscles connecting with these lines:

• Front functional line: adductor longus
• Back functional line: contralateral gluteus maximus
• Superficial Front line: rectus femoris
• Superficial Back line: hamstrings
• Lateral line: gluteus maximus, Tensor Fascia Latae, Iliotibial Track/Hip Abductors
• Spiral Line: Iliotibial track, Tensor Fascia Latae
• Deep Front Line: Iliacus, Psoas, Adductor Brevis and Longus, Adductor Magnus and Minimus

This video further explains the concept of fascia lines:

Examples of fascia connections in the hip joint:

• The fascia of hip adductors continues to the pelvis and influences the urogenital and pelvic diaphragms
• The iliacus fascia is continuous with the deep pelvic fascia
• The fascia of the gluteus medius is continuous with the fascia of the abdominal obliques at the iliac crest
• There is fascial continuity between the obturator internus and the iliacus which further extends into internal obliques and the diaphragm.

Clinical relevance

1. Piriformis syndrome is described as irritation of the sciatic nerve at the level of the piriformis muscle. It is a combination of symptoms involving the hip, buttock, and upper thigh. Possible causes include trauma, hematoma, excessive sitting, and anatomic variations of the muscle and nerve.
2. Gluteus medius and gluteus minimus muscles weakness can present with Trendelenburg gait.
3. External myofascial mobilisation approach based on fascial connectivity including ipsilateral latissimus dorsi, ipsilateral thoracolumbar fascia and contralateral gluteus maximus posteriorly, ipsilateral external oblique and contralateral internal oblique, and hip adductor complex anteriorly led to significant symptom improvement in the spastic chronic pelvic pain syndrome.