The hip flexor muscles at the front of the hip joint primarily function to flex the hip joint (bring your knee up forwards in front). They include the Iliopsoas, rectus femoris, sartorius and tensor fasciae latae. The iliopsoas is the main hip flexor muscler group, whilst the others assist.
What are the hip flexor muscles?
The hip flexor muscles include:
Iliopsoas
The iliopsoas muscle is actually a group of two muscles located in the front of the hip joint: the iliacus and the psoas major. It is the most powerful hip flexor muscle.
Rectus femoris
The rectus femoris muscle is one of the four muscles making up the quadriceps group at the front of the thigh. It originates from the anterior inferior iliac spine of the pelvis and attaches to the patella via the quadriceps tendon and then continues to attach to the tibia via the patellar ligament.
Sartorious
The sartorius muscle is the longest muscle in the human body and has a unique oblique course from the lateral side of the hip to the inside (medial) side of the knee.
Tensor fascia latae
The tensor fascia latae muscle on the lateral side of the hip. It originates from the iliac crest of the pelvis and attaches to the iliotibial band, which runs down the lateral side of the thigh and attaches to the tibia.
What is the function of the hip flexor muscles?
While the iliopsoas muscles are considered the primary hip flexors, the rectus femoris and tensor fasciae latae also contribute to hip flexion, particularly in activities like running, walking, and climbing stairs. These muscles play a crucial role in maintaining proper posture, facilitating movements involving the hips and legs, and providing stability to the pelvis and spine. Stretching and strengthening exercises targeting the hip flexor muscles are often included in rehabilitation and fitness programs to improve flexibility, strength, and function.
Hip flexor muscle assessment tests
Your physio or therapist may use the following tests to asses the hip flexor muscles
Thomas test
The Thomas test assess whether you have tight hip flexor and/or quadriceps muscles. The patient pulls one knee towards their chest, holding it with their hands to keep the lower back flat against the table. If the opposite thigh lifts off the table or the knee extends due to tightness, it indicates tight hip flexors. Typically, the iliopsoas and/or rectus femoris).
Sports injuries affecting the hip flexor muscles
The following injuries relate to the muscles which flex the hip.
Iliopsoas bursitis & tendonitis
Iliopsoas bursitis is inflammation of a small sac of fluid which sits between the tendon and bone. Tendonitis is inflammation of the tendon. Both Iliopsoas bursitis and Iliopsoas tendon inflammation have similar symptoms of gradual onset pain, deep in the groin.
