The Investing Layer of the Deep Cervical Fascia does not Exist between the Sternocleidomastoid and Trapezius Muscles

Abstract

We sought to describe the 3-dimensional organization of connective tissues in the suboccipital region. We conducted a sectional anatomic investigation with the use of E12 sheet plastination. Six human adult cadavers (2 male and 4 female; age range, 54 to 86 years) were used in this study. Five of them were sectioned as 2.5-mm-thick coronal (1 cadaver), transverse (2 cadavers), or sagittal (2 cadavers) sections. No aggregation of fibrous connective tissue was seen between the sternocleidomastoid and trapezius muscles. The intervening space was fully occupied by fatty tissue that was indistinguishable from the subcutaneous tissue. The investing layer of the deep cervical fascia is incomplete so that the carotid sheath is directly exposed to the subcutaneous tissue via a gap between the sternocleidomastoid and trapezius muscle. This anatomic feature should be considered when designing a minimally invasive endoscopic approach to the carotid sheath and the surrounding deep cervical structures.