Antagonist Gluteus maximus | ||
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Actions flexes and rotates laterally thigh | ||
The iliacus (/ᵻˈlaɪ.əkəs/) is a flat, triangular muscle which fills the iliac fossa.
Contents
Structure
The iliacus arises from the iliac fossa on the interior side of the hip bone, and also from the region of the anterior inferior iliac spine (AIIS). It joins the psoas major to form the Iliopsoas as which it proceeds across the iliopubic eminence through the muscular lacuna to its insertion on the lesser trochanter of the femur. Its fibers are often inserted in front of those of the psoas major and extends distally over the lesser trochanter.
Innervation
The iliopsoas is innervated by the femoral nerve and direct branches from the lumbar plexus.
Function
In open-chain exercises, as part of the iliopsoas, the iliacus is important for lifting (flexing) the femur forward (i.e. front scale). In closed-chain exercises, the iliopsoas bends the trunk forward and can lift the trunk from a lying posture (i.e. sit-ups, back scale) because the psoas major crosses several vertebral joints and the sacroiliac joint. From its origin in the lesser pelvis the iliacus acts exclusively on the hip joint.