Wikipedia
Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue which can surround individual muscles, and also surround groups of muscles to separate into fascial compartments.
This fibrous connective tissue interpenetrates and surrounds the muscles, bones, nerves and blood vessels of the body. It provides connection and communication in the form of aponeuroses, ligaments, tendons, retinacula, joint capsules, and septa. The deep fasciae envelop all bone ( periosteum and endosteum); cartilage ( perichondrium), and blood vessels ( tunica externa) and become specialized in muscles ( epimysium, perimysium, and endomysium) and nerves ( epineurium, perineurium, and endoneurium). The high density of collagen fibers is what gives the deep fascia its strength and integrity. The amount of elastin fiber determines how much extensibility and resilience it will have.