Structural and functional anatomy of the retinaculum cutis: review and new insights

Practitioners worldwide have become interested in fascia and how it relates to human appearance and movement. Our study describes an anatomic layer containing connective tissue attachments between the dermis and threconstructive surgery and physical therapye underlying deep investing fascia. Classically labeled as the retinacula cutis (RCs) or fatty septa within the hypodermis, we sometimes refer to these connective tissue attachments as the subcutaneous endoskeleton or Cinderella Layer for their overlooked importance. The significance of these structural attachments as functional tethers has, to a large degree, been neglected. We are adding a descriptive classification system to various types of RCs, while further exploring the important clinical implications of the anatomy through a lens of reconstructive surgery and physical therapy. Dissection of 25 fresh, lightly embalmed, and hypertonic saline embalmed cadavers complemented years of clinical observation to identify and describe consistent relationships between the skin, hypodermis, fascia, and, in some cases, periosteum. We qualitatively noted whether the connective tissue attachments within the hypodermis were long or short, dense or filmy, elastic or rigid, and further subdivided the collagen and elastin bands into functional categories. Identification of the RCs was also attempted on sections from the Visible Human Project (National Library of Medicine). Our dissections revealed numerous and consistent attachments between the fascia and dermis. These RCs are found to have distributed fascial-dermal attachments with directional organization. The origin is typically a continuous fascial covering of muscle or bone, and the insertion is the dermal layer of the skin. The gross morphology of these attachments reinforces their aesthetic and functional purpose as a boundary, anchor, animator, accordion or elastic framework. In most areas of the body, the RCs serve more than one of these purposes. A few of these complex areas are highlighted separately. Gaining an appreciation for the concept of fascial-dermal attachments that define the human body as an organized network of compartments, contours, and creases is relevant to the surgeon, therapist, artist, and student of anatomy alike. Once recognized, their function can often be appreciated. Cataloging and categorizing the RCs with respect to their morphological and functional variability is a crucial addition to modern clinical anatomy.