Getting to know the muscles

The Psoas major is a long fusiform muscle placed on the side of the lumbar region of the vertebral column and brim of the lesser pelvis.

the Hip flexors are a group of muscles (including the iliopsoas which passes through the pelvis) that act to flex the femur onto the lumbo-pelvic complex.

* The hip flexors include:
o Tensor fasciae latae
o Sartorius muscle
o Pectineus muscle
o Adductor longus muscle
o Adductor brevis muscle
* Part of the Quadriceps:
o Rectus femoris muscle
* Collectively known as the Iliopsoas:
o Psoas major muscle
o Psoas minor muscle
o Iliacus muscle

The muscles also contribute to flexing the lower back onto the pelvis when the pelvis is fixed, or flexing the pelvis onto the lower back when the lower back is fixed.


The Psoas minor is a long, slender muscle that is placed (when present) in front of the psoas major muscle. It is absent in 40% of individuals. It arises from the sides of the bodies of the twelfth thoracic and first lumbar vertebrae and from the intervertebral discs separating them. It ends in a long flat tendon which is inserted into the pectineal line and iliopectineal eminence, and, by its lateral border, into the iliac fascia

The Iliacus is a flat, triangular muscle, which fills the iliac fossa.

It arises from the upper two-thirds of this fossa, and from the inner lip of the iliac crest; behind, from the anterior sacroiliac and the iliolumbar ligaments, and base of the sacrum; in front, it reaches as far as the anterior superior iliac spine and anterior inferior iliac spine, and the notch between them.

The fibers converge to be inserted into the lateral side of the tendon of the Psoas major, which contributes to flexing the femur anteriorly onto the pelvis. Some of the iliacus fibers may reach the body of the femur, for about 2.5 cm. below and in front of the lesser trochanter. The Iliacus is sometimes considered a part of the Iliopsoas group of hip flexor muscles. This muscle is innervated by the anterior branches of the Femoral nerve (anterior branches of L2-3).