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Anterior hip and thigh muscles.
Origin Iliac fossa and lumbar spine
Insertion Lesser trochanter of femur
Artery Medial femoral circumflex artery and iliolumbar artery
Nerve Branches from L1 to L3
Actions Flexion of hip
Antagonist Gluteus maximus and the posterior compartment of thigh
Latin Musculus iliopsoas
TA98 A04.7.02.002
TA2 2593
FMA 64918
Anatomical terms of muscle

The iliopsoas muscle ( /ˌɪliˈs.əs/ ) refers to the joined psoas and the iliacus muscles. The two muscles are separate in the abdomen, but usually merge in the thigh. They are usually given the common name iliopsoas. The iliopsoas muscle joins to the femur at the lesser trochanter. It acts as the strongest flexor of the hip.


The iliopsoas muscle is supplied by the lumbar spinal nerves L1-3 (psoas) and parts of the femoral nerve (iliacus).


The iliopsoas muscle is a composite muscle formed from the psoas major muscle, and the iliacus muscle. The psoas major originates along the outer surfaces of the vertebral bodies of T12 and L1-L3 and their associated intervertebral discs. [1] The iliacus originates in the iliac fossa of the pelvis. [2]

The psoas major unites with the iliacus at the level of the inguinal ligament. It crosses the hip joint to insert on the lesser trochanter of the femur. [1] The iliopsoas is classified as an "anterior hip muscle" or "inner hip muscle". [2] The psoas minor does contribute to the iliopsoas muscle.

The inferior portion below the inguinal ligament forms part of the floor of the femoral triangle.

Nerve supply

The psoas major is innervated by direct branches of the anterior rami off the lumbar plexus at the levels of L1-L3, while the iliacus is innervated by the femoral nerve (which is composed of nerves from the anterior rami of L2-L4).


The iliopsoas is the prime mover of hip flexion, and is the strongest of the hip flexors (others are rectus femoris, sartorius, and tensor fasciae latae). [3] The iliopsoas is important for standing, walking, and running. [2] The iliacus and psoas major perform different actions when postural changes occur.

The iliopsoas muscle is covered by the iliac fascia, which begins as a strong tube-shaped psoas fascia, which surround the psoas major muscle as it passes under the medial arcuate ligament. Together with the iliac fascia, it continues down to the inguinal ligament where it forms the iliopectineal arch which separates the muscular and vascular lacunae. [4]

Clinical significance

It is a typical posture muscle dominated by slow-twitch red type 1 fibers. Since it originates from the lumbar vertebrae and discs and then inserts onto the femur, any structure from the lumbar spine to the femur can be affected directly. A short and tight iliopsoas often presents as externally rotated legs and feet. It can cause pain in the low or mid back, SI joint, hip, groin, thigh, knee, or any combination. The iliopsoas gets innervation from the L2-4 nerve roots of the lumbar plexus which also send branches to the superficial lumbar muscles. The femoral nerve passes through the muscle and innervates the quadriceps, pectineus, and sartorius muscles. It also comprises the intermediate femoral cutaneous and medial femoral cutaneous nerves which are responsible for sensation over the anterior and medial aspects of the thigh, medial shin, and arch of the foot nerves. The obturator nerve also passes through the muscle which is responsible for the sensory innervation of the skin of the medial aspect of the thigh and motor innervation of the adductor muscles of the lower extremity (external obturator, adductor longus, adductor brevis, adductor magnus, gracilis) and sometimes the pectineus. Any of these innervated structures can be affected.


Iliopsoas muscle is a common site of bleeding in patients who are undergoing blood anticoagulation. [5]

Additional images

See also

Related Research Articles

Human leg Lower extremity or limb of the human body (foot, lower leg, thigh and hip)

The human leg, in the general word sense, is the entire lower limb of the human body, including the foot, thigh and even the hip or gluteal region. However, the definition in human anatomy refers only to the section of the lower limb extending from the knee to the ankle, also known as the crus or, especially in non-technical use, the shank. Legs are used for standing, and all forms of locomotion including recreational such as dancing, and constitute a significant portion of a person's mass. Female legs generally have greater hip anteversion and tibiofemoral angles, but shorter femur and tibial lengths than those in males.

Sartorius muscle Longest muscle in the human body

The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment.

Femoral triangle

The femoral triangle is an anatomical region of the upper third of the thigh. It is a subfascial space which appears as a triangular depression below the inguinal ligament when the thigh is flexed, abducted and laterally rotated.

Genitofemoral nerve

The genitofemoral nerve refers to a nerve that is found in the abdomen. Its branches, the genital branch and femoral branch supply sensation to the upper anterior thigh, as well as the skin of the anterior scrotum in males and mons pubis in females. The femoral branch is different from the femoral nerve, which also arises from the lumbar plexus.

Pectineus muscle Adductor of the thigh

The pectineus muscle is a flat, quadrangular muscle, situated at the anterior (front) part of the upper and medial (inner) aspect of the thigh. The pectineus muscle is the most anterior adductor of the hip. The muscle does adduct and internally rotate the thigh but its primary function is hip flexion.


In human anatomy, the groin is the junctional area between the abdomen and the thigh on either side of the pubic bone. This is also known as the medial compartment of the thigh that consists of the adductor muscles of the hip or the groin muscles. A pulled groin muscle usually refers to a painful injury sustained by straining the hip adductor muscles.

Hip Anatomical region between the torso and the legs, holding the buttocks and genital region

In vertebrate anatomy, hip refers to either an anatomical region or a joint.

Psoas major muscle Long fusiform muscle located in the lumbar region

The psoas major is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the iliopsoas. In animals, this muscle is equivalent to the tenderloin.

Iliacus muscle Flat, triangular muscle which fills the iliac fossa

The iliacus is a flat, triangular muscle which fills the iliac fossa. It forms the lateral portion of iliopsoas, providing flexion of the thigh and lower limb at the acetabulofemoral joint.

Adductor brevis muscle Muscle in the thigh situated immediately behind the pectineus and adductor longus

The adductor brevis is a muscle in the thigh situated immediately deep to the pectineus and adductor longus. It belongs to the adductor muscle group. The main function of the adductor brevis is to pull the thigh medially. The adductor brevis and the rest of the adductor muscle group is also used to stabilize left to right movements of the trunk, when standing on both feet, or to balance when standing on a moving surface. The adductor muscle group is used pressing the thighs together to ride a horse, and kicking with the inside of the foot in soccer or swimming. Last, they contribute to flexion of the thigh when running or against resistance.

Adductor longus muscle Skeletal muscle located in the thigh

In the human body, the adductor longus is a skeletal muscle located in the thigh. One of the adductor muscles of the hip, its main function is to adduct the thigh and it is innervated by the obturator nerve. It forms the medial wall of the femoral triangle.

Adductor magnus muscle Muscle in the thigh

The adductor magnus is a large triangular muscle, situated on the medial side of the thigh.

Femoral nerve

The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee.

Muscles of the hip Causes movement in the hip.

In human anatomy, the muscles of the hip joint are those muscles that cause movement in the hip. Most modern anatomists define 17 of these muscles, although some additional muscles may sometimes be considered. These are often divided into four groups according to their orientation around the hip joint: the gluteal group; the lateral rotator group; the adductor group; and the iliopsoas group.

Lumbar plexus

The lumbar plexus is a web of nerves in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve. Additionally, the ventral rami of the fourth lumbar nerve pass communicating branches, the lumbosacral trunk, to the sacral plexus. The nerves of the lumbar plexus pass in front of the hip joint and mainly support the anterior part of the thigh.

Obturator nerve

The obturator nerve in human anatomy arises from the ventral divisions of the second, third, and fourth lumbar nerves in the lumbar plexus; the branch from the third is the largest, while that from the second is often very small.

Lateral cutaneous nerve of thigh

The lateral cutaneous nerve of the thigh is a cutaneous nerve that innervates the skin on the lateral part of the thigh.

Anterior compartment of thigh Muscles which extend the knee and flex the hip

The anterior compartment of thigh contains muscles which extend the knee and flex the hip.

Outline of human anatomy Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

Pelvis Lower part of the trunk of the human body between the abdomen and the thighs

The pelvis is either the lower part of the trunk of the human body between the abdomen and the thighs or the skeleton embedded in it.


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