An anatomical comparison of the fasciae of the thigh: A macroscopic, microscopic and ultrasound imaging study

Abstract

Although the number of Ultrasound (US) imaging studies investigating the fascial layers are becoming more numerous, the majority tend to use different reference points and terminology to describe their findings. The current work set out to compare macroscopic and microscopic data of specimens of the fascial layers of the thigh with US imaging findings. Specimens of the different fascial layers of various regions of the thigh were collected for macroscopic and histological analyses from three fresh cadavers and compared with in vivo US images of the thighs of 20 healthy volunteers. The specimens showed that the subcutaneous tissue of the thigh is made up of three layers: a superficial adipose layer, a membranous layer/superficial fascia, and a deep adipose layer. The deep fascia is composed of an aponeurotic fascia, which envelops all the thigh muscles and is laterally reinforced by the iliotibial tract and an epimysial fascia, which is specific for each muscle. The morphometric measurements of the thickness of the superficial fascia were different (anterior: 153.2 ± 39.3 µm; medial: 128.4 ± 24.7 µm; lateral: 154 ± 28.9 µm; and posterior: 148.8 ± 33.2 µm) as were those of the deep fascia (anterior: 556.8 ± 176.2 µm; medial: 820.4 ± 201 µm; lateral: 1112 ± 237.9 µm; and posterior: 730.4 ± 186.5 µm). The US scans showed a clear picture of the superficial adipose tissue, the superficial fascia, and the deep adipose tissue, as well as the deep fasciae. The epimysial and aponeurotic fasciae of only some topographic areas could be independently identified. The US imaging findings confirmed that the superficial and deep fascia have different thicknesses, and they showed that the US measurements were always larger with respect to those produced by histological analysis (p < 0.001) probably due to shrinkage during the processing. The posterior region (level 1) of the superficial fascia had, for example, a mean thickness of 0.56 ± 0.12 mm at US, while the histological analysis showed that it was 148.8 ± 33.2 µm. Showing a similar pattern, the thickness of the deep fascia was as follows: 1.64 ± 0.85 mm versus 730.4 ± 186.5 µm. Study results have confirmed that US can be considered a valid, non‐invasive instrument to evaluate the fascial layers. In any event, there is a clear need for a set of standardised protocols since the thickness of the fascial layers of different parts of the human body varies and the data obtained using inaccurate reference points are not reproducible or comparable. Given the inconsistent terminology used to describe the fascial system, it would also be important to standardise the terminology used to define its parts. The difficulty in distinguishing between the epimysial and aponeurotic/deep fascia can also impede data interpretation.

A Closer Look at the Cellular and Molecular Components of the Deep/Muscular Fasciae

“…The antebrachial fascia has a mean thickness of 755 μm (SD ± 115 μm) and presents two reinforcements: the lacertus fibrosus and the retinacula of the wrist. These dimensions are consistent with those reported by Pirri et al [ 23 ], whose in vivo data were obtained via ultrasound evaluation. This study, which evaluated the deep fasciae of different regions of the thigh, uncovered a mean thickness of 556.8 ± 176.2 µm in the anterior compartment, of 820.4 ± 201 µm in the medial one, of 1112 ± 237.9 µm in the lateral one, and of 730.4 ± 186.5 µm in the posterior one.…”

Ultrasound Imaging of Crural Fascia and Epimysial Fascia Thicknesses in Basketball Players with Previous Ankle Sprains Versus Healthy Subjects

“…To eliminate the influence of possible thickness variations, three equidistant points per image were measured and the resulting values were averaged for analysis. The scanner settings were kept constant during the study [ 37 ].…”

Tenderness of the Skin after Chemical Stimulation of Underlying Temporal and Thoracolumbar Fasciae Reveals Somatosensory Crosstalk between Superficial and Deep Tissues

“…Subjects were advised to lie on a bench facedown, thus minimizing back muscle contraction. Concentric bipolar needle electrodes (diameter 0.46 mm, stimulation area 0.07 mm 2 , CareFusion, USA) were positioned under ultrasound guidance (M-Turbo ultrasound system; Sonosite, Munich, Germany) bilaterally into the thoracolumbar fascia (deep fascia [ 40 ]), and into the multifidus muscle, 10 mm below the surface of the thoracolumbar fascia and approximately 2 cm lateral to the midline at lumbar level L3/L4. Electrical stimuli (pulse width: 2 ms) were applied via a constant current stimulator (DS7A; Digitimer, Welwyn Garden City, UK).…”

“…In an exploratory dose-finding pilot experiment, three different amounts (50 µL, 200 µL and 800 µL) of hypertonic saline (5.8%) were injected into the multifidus muscle and the overlying thoracolumbar fascia (deep fascia [ 40 ]) at spinal levels L3/L4 in 16 healthy volunteers (11 female, 5 male; 23.3 ± 3.1, mean ± SD) to delineate adequate conditions for the stimulation intensity in order to be able to compare different tissues. Therefore, after injection, the volunteers were asked to rate the magnitude of perceived pain on a numerical rating scale (NRS) with the endpoints 0 (= no pain) and 100 (= most intense pain imaginable).…”

“…In 16 healthy volunteers (8 female, 8 male; 27.3 ± 4.1, mean ± SD), we injected 100 µL of hypertonic saline at different fascial sites to compare the impact of chemical stimulation in different fasciae. These injection sites were the iliotibial band (IT band) at a mid-distance between the greater trochanter and the fibular head at the lateral midline, the TLF approximately 2 cm lateral to the midline at the L3/L4 level overlying the multifidus muscle, and the fascia nuchae approximately 3-4 cm lateral to the midline at the C7/Th1 level overlying the trapezius muscle (all deep fascia [40]). In addition, we made an injection subcutaneously onto the temporal fascia (i.e., into the superficial fascia/superficial adipose tissue [41]).…”