Hello again, everyone! It’s Matt from Kenhub, and in this tutorial, we will discuss the
anatomy, innervation, and function of the iliopsoas muscle.
The iliopsoas muscle belongs to the inner hip muscles. It consists of a complex of two
muscles with different areas of origin.
The iliopsoas belongs to the striated musculature, and the innervation is carried by the femoral
nerve as well as the direct branches of the lumbar plexus, both seen highlighted in green
on these images.
The iliopsoas muscle consists of the psoas major and the iliacus muscles.
The psoas major muscle originates from the first to fourth lumbar vertebrae, the costal
processes of all lumbar vertebrae, and the twelfth thoracic vertebrae and inserts at
the lesser trochanter of the femur.
The iliacus muscle originates from the iliac fossa and inserts with the psoas major at
the lesser trochanter. The psoas major and the iliacus muscle unify in the lateral pelvis
shortly before the inguinal ligament, becoming the iliopsoas muscle. There, they pass below
the inguinal ligament through the muscular lacuna together with the femoral nerve.
Both muscles are completely surrounded by the iliac fascia. The lumbar plexus lies dorsally
from the psoas major muscle, which is penetrated by the genitofemoral nerve. Medially from
the psoas major runs the sympathetic trunk.
The iliopsoas muscle is the strongest flexor of the hip joint, which makes it an important
muscle for walking. In the supine position, it decisively supports the straightening of
the upper body. For example, during sit-ups. Furthermore, it rotates the thigh laterally.
A unilateral contraction leads to a lateral flexion of the lumbar vertebrae column.
Altogether, the iliopsoas muscle plays a significant role in the movement and stabilization of
This video is more fun than reading a textbook, right? If you want more videos, interactive
quizzes, articles, and an atlas of human anatomy, click on the “Take me to Kenhub” button.
It is time to say goodbye to your old textbooks and say hello to your new anatomy learning
See you there!