Fascia is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs. Fascia is classified by layer, as superficial fascia, deep fascia, and visceral or parietal fascia...
The hip flexors are a group of five muscles that connect the femur (or thigh bone) to the pelvis, they are located near the top of your thighs that are key players in moving your lower body.
They are responsible for walking, kicking, bending, and swiveling your hips. Movement, your hip flexors can stretch or tear. A hip flexor strain can be mildly uncomfortable or so severe that you have trouble walking
The psoas (pronounced SO-az) is the most significant player in a group of muscles called the hip flexors: together they contract to pull the thigh and the torso toward each other. They also provide stability to your lower back, pelvis, and hips.