Morphological Investigation of Superficial Fascia Relationships With the Skin and Underlying Tissues in the Canine Hindlimb

The morphology of the superficial fascia in the canine hindlimb is still poorly understood and incompletely described. The present study aimed to elucidate the macroscopic and microscopic structures of the superficial fascia, thereby clarifying its functional role. Cadavers were investigated for anatomic description (N = 38), ultrasonic scanning (N = 2), and histological analyses (N = 10) of this tissue in the hindlimb. The superficial fascia was identified as a shiny, white fibroelastic layer that adhered to the skin through fibrous septa. It was organized into sublayers enveloping the cutaneous muscle and large blood vessels. In certain areas, superficial fascia fused with the deep fascia or skin, creating fascial bursae. These bursae included the ischiatic bursa, an iliac bursa, a prepatellar subfascial bursa, a prepatellar subcutaneous bursa, and the tarsal fascial bursa. Microscopically, the superficial fascia presented as a layer of dense connective tissue characterized by irregularly arranged collagen and elastic fibers. The superficial fascia was firmly attached to the skin and deep fascia by numerous fibrous tissue strands. Within both, the superficial fascia and fascial bursae, several mechanoreceptors and nerve endings were identified, including Ruffini's corpuscles, Pacinian corpuscles, and Golgi-Mazzoni corpuscles. The organization of the superficial fascia and its attachments suggest a mechanical role in supporting structures and resisting loads during movement. The fibrous septa anchors fascia to the skin, providing stability and resistance against external forces, as well as protecting the nerves and blood vessels that pass towards the skin. Existing fascial bursae probably assist in decreasing pressure and facilitating freedom of movement adjacent to bony prominences. Elasticity and connectivity of the superficial fascia may explain the various responses to multidirectional loading. Furthermore, the presence of free nerve endings and mechanoreceptors within the fascia suggests that it may contribute to proprioception of the hindlimb, enhancing the awareness of body movement.