MUSCLES-ILIOPSOAS

SUMMARY

1. ILIACUS - arises from the iliac fossa. Entering the thigh beneath the lateral part of the inguinal ligament, it combines with the psoas tendon (lying in front of it) to be inserted into the lesser trochanter. Supplied by the femoral nerve. 
2. The iolipsoas passes in front of the capsule of the hip joint. 

3. The lower part of the iliac fossa is bare of muscle and is occupied by the iliac bursa (which may communicate with the cavity of the hip joint) and separates the iliopsoas from the capsule of the hip joint.
 
4. PSOAS - arises from the lumbar spine, passes into the thigh beneath the middle part of the inguinal ligament. It combines with the iliacus tendon (which lies in front of it) to be inserted into the lesser trochanter. Supplied by L1-L3 nerve roots. Remember that the psoas also flexes the lumbar vertebrae, whereas the iliacus does not. 

Reference(s)

R.M.H McMinn (1998). Last’s anatomy: regional and applied. Edinburgh: Churchill Livingstone.
Gray, H., Carter, H.V. and Davidson, G. (2017). Gray’s anatomy. London: Arcturus.