Original Editor - Mandeepa Kumawat Top Contributors - Mandeepa Kumawat and Kim Jackson


The iliacus muscle is shaped like a triangle, flat and an exact fit of the iliac fossa — the curved surface of the largest pelvic bone. Together with the psoas major muscle, it is also called the iliopsoas muscle.A portion of this muscle is attached to the iliac fossa, two-thirds from its top. Another portion is attached to the inside portion of the iliac crest, the top, outer portion of the pelvic bone.Other fibers of this muscle are attached to the iliolumbar and anterior sacroiliac ligaments (located at the base portion of the sacrum) and up to the anterior iliac spines (bony projections that lie toward the edges of the iliac). These muscle fibers then converge and insert on the tendon at the lateral (outer) side of the psoas major muscle, which stretches from the lumbar spine in the lower back to the lower pelvis. Some of these fibers extend to the femur bone, or thighbone.[1]




Upper 2/3 of iliac fossa of ilium, internal lip of iliac crest, lateral aspect of sacrum, ventral sacroiliac ligament, and lower portion of iliolumbar ligament


Lesser trochanter of femur. Its fibers are often inserted in front of those of the psoas major and extend distally over the lesser trochanter.

Nerve supply

The iliacus muscle is supplied with nerves by the branches of the second and third nerves of the lumbar area through the femoral nerve.(L2,L3)


Lumbar branch of iliopsoas branch of internal iliac artery and medial circumflex femoral artery.


  • The iliacus muscles flexes and externally rotates the femur.
  • It is also one of the key muscles that helps to maintain proper body posture.
  • When combined with the psoas muscle the two muscles are considered the strongest hip flexors in the body.
  • It is also one of the key muscles that helps to maintain proper body posture.
  • The Iliacus muscle can also add to an anterior tilt of the pelvis (down and forward).
  • Just like the iliacus, the iliopsoas is responsible for hip flexion. This muscle is also involved in trunk flexion, which is bending the trunk forward such as when you perform a sit-up or bend down to tie your shoes.
  • The iliacus is also continuously active during walking but psoas major is only active (during gait) shortly preceding and during the early swing phase.
  • The iliacus muscle eccentrically controls lateral sidebending of the trunk.

Clinical relevance

  1. Excessive use of the muscle can make it shorter, especially if someone does desk job each day. This muscle can also become shorter through lots of exercising without stretching. As this muscle shortens, it can start to cause dysfunction and injuries in the hip and pelvic regions of the body, such as:
  • Trigger points - tight areas or knots in the iliacus muscle that are painful, tender, and stiff.
  • Iliacus ischemia - a condition of reduced blood flow to the muscle.
  • Hip, knee, and lower back problems - If the iliacus on one side of the hip becomes shorter than the iliacus on the other, this can cause a person to walk with imbalanced hips, affecting the normal gait of a person. (Try walking while keeping one hip lower than the other, you will probably start to feel pain and irritation in your hips, knees, and lower back)

The main symptom of iliacus dysfunction is pain. This pain can be in the hips, groin, lower back, and upper thigh regions of the body. Other symptoms include:

  • Stiffness
  • Decreased range of motion
  • Tenderness[5]

2. Traumatic iliacus muscle injury is rare; it is usually caused by trauma or intense exercise involving the pelvic girdle; it can produce a hematoma with femoral nerve neuropathy.[6] Spontaneous muscle hematomas occur in patients with coagulation disorders.It causes intense pain in the right buttock, groin and iliac fossa, with an inability for hip flexion and ambulation caused by inadequate exercise (supine double leg lifts).Ecchymoses may be present in the upper thigh.

3. Iliacus compartment syndrome[7]

Iliacus compartment syndrome is a rare retroperitoneal compartment neuropathy caused by bleeding within the iliacus muscle leading to hematoma formation and compression upon the femoral nerve, causing both sensory and motor deficits.Iliac hematomas are rare and can be caused by traumatic and non-traumatic injury, and can be exacerbated by complications of anticoagulant therapy.Delaying surgical evacuation of the hematoma can lead to prolonged or permanent disability. However, there are other reports describing good recovery with non-operative management. Non-surgical intervention is recommended if radiological studies do not explicitly confirm the presence of a discreet hematoma compressing the femoral nerve, unless progression of symptoms increases.



Have client supine with a pillow under the knees.Flex the knee and slightly laterally rotated Place palpating hand on the anterior iliac crest and palpate into the iliac fossa with your finger tips. Most of the iliacus is not palpable .Ask the client to actively flex the thigh at the hip joint and feel for the contraction of the iliacus .



Have the client stand against a wall, with heels (feet) apart, and shoulders and head touching the wall. Normal is the ability to posterior tilt to touch the small of the back against the wall. If the client cannot posterior tilt by flattening their back onto the wall with the feet apart and the hips and knees straight, but can do so with knees bent and the hip flexed, the restriction could be shortened iliacus.

Muscle length test


The iliacus are shortened during activities that flex the hips, such as sitting. Because they increase the arch of the lower back, tight hip flexors are notorious for causing lower-back pain.

  • Start: Lie on your back on a stable table with your legs hanging off the edge. Grab your left knee with both hands and pull it gently toward your chest.
  • Stretch: Stretch the hip flexors on the right side by letting the right leg hang for 10 seconds.
  • Contract: Resist by lifting your right leg toward the ceiling for six seconds.
  • Relax for five seconds.
  • Stretch: Hang your right leg off the table again. Hold for 10 to 20 seconds. For a more intense stretch, hang a heavy bag from your right foot. Switch sides.
Iliacus stretch.jpeg

Strengthening exercises

hanging leg raise
Iliacus theraband.jpg
Lying scissor kick.png


Pelvis - Muscles
  1. Iliacus Muscle Origin, Function & Anatomy | Body Maps (accessed 17 June 2018)
  2. Iliacus - UW Radiology (accessed 18 june 2018)
  3. Iliacus Muscle: Definition & Function Chapter 9 Lesson 1 Instructor:Dan Washmuth (accessed 18 June 2018)
  4. Leon Chaitow Judith DeLany Clinical Application of Neuromuscular Techniques Volume 2: The Lower Body 2nd Edition • 2012
  5. Iliacus Muscle Dysfunction: Symptoms & Injuries Chapter 9 Lesson 2 (accessed 19 June 2018)
  6. Magaña-Reyes J, Domínguez-Gasca LG, García-Luna A, Domínguez-Carrillo LG. Iliacus muscle injury caused by inadequate exercise. Acta ortopedica mexicana. 2016 Dec 15;30(3):154-7.
  7. Mwipatayi BP, Daneshmand A, Bangash HK, Wong J. Delayed iliacus compartment syndrome following femoral artery puncture: case report and literature review. Journal of surgical case reports. 2016 Jun 1;2016(6).
  8. Class 6 Ap1 Muscles1 Muscles of the Pelvis and Thigh (accessed 19 June 2018)