The iliacus and the psoas major muscles are collectively known as the muscle because they share a common insertion on the of the femur.

Iliopsoas muscle

Lesser trochanter

Explanation:

This two muscles, iliacus and psoas are the most important flexors of the hips. They have different origins: the psoas originates in vertebral bodies (T12, L1-L3) and the iliacus originates in the pelvis (iliac fossa).

Because of psoas origin, it also affects vertebral column position (specially at lumbar lordosis)

humans, along with other animals and plants, have linear chromosomes that are arranged in pairs within the nucleus of the cell. the only human cells that do not contain pairs of chromosomes are reproductive cells, or gametes, which carry just one copy of each chromosome.