The paravertebral spread that occurs after erector spinae plane block may be volume-dependent. This cadaveric study was undertaken to compare the extent of paravertebral spread with erector spinae plane block using different dye volumes. After randomization, twelve erector spinae plane blocks were performed bilaterally with either 10 ml or 30 ml of dye at the level of T5 in seven unembalmed cadavers except for two cases of unexpected pleural puncture using the 10 ml injection. Direct visualization of the paravertebral space by endoscopy was performed immediately after the injections. The back regions were also dissected, and dye spread and nerve involvement were investigated. A total of five 10 ml injections and seven 30 ml injections were completed for both endoscopic and anatomical evaluations. No paravertebral spread was observed by endoscopy after any of the 10-ml injections. Dye spread to spinal nerves at the intervertebral foramen was identified by endoscopy at adjacent levels of T5 (median: three levels) in all 30 ml injections. In contrast, the cases with two, four, and three out of five were stained at only the T4, T5, and T6 levels, respectively, with the 10 ml injection. Upon anatomical dissection, all blocks were consistently associated with posterior and lateral spread to back muscles and fascial layers, especially with the 30 ml injections, which showed greater dye expansion. In one 30 ml injection, sympathetic nerve involvement and epidural spread were observed at the level of the injection site. Although paravertebral spread following erector spinae plane block increased in a volume-dependent manner, this increase was variable and not pronounced. As the injectate volume increased for the erector spinae blocks, the injectate spread to the back muscles and fascial layers seemed to be predominantly increased compared with, the extent of paravertebral spread.

Background: The superior labial artery, which is a branch of the facial artery, supplies the upper lip area. The aim of this study was to determine the distribution pattern of the superior labial artery and provide precise topographic information of the artery for dermal filler injection. Methods: Sixty hemifaces from 18 Korean and 18 Thai cadavers were used for this study. The various distribution patterns of the superior labial artery were classified according to its relationship with the facial artery. Results: The course of the superior labial artery was classified into four types: type I (56.7 percent), in which the artery and the alar branch both arise directly and independently from the facial artery; type II (21.7 percent), in which the superior labial artery branches off from the facial artery and then gives off an alar branch; type III (15.0 percent), in which it is the terminal branch of the facial artery; and type IV (6.7 percent), in which the artery is absent. The origin of the superior labial artery was located 12.1 ± 3.1 mm (mean ± SD) lateral and at a variable angle of 42.8 ± 26.9 degrees relative to the mouth corner. Conclusions: The superior labial artery proceeded from the origin of the artery located within a 1.5-cm-side square superolateral to the mouth corner as running along the vermilion border of the upper lip to the facial sagittal midline at a depth of 3 mm. Thus, clinicians should be careful when injecting dermal filler into this area.

Improper manipulation of injectable treatments to the face can result in disastrous vascular complications. The aim of the present study was to elucidate the detoured course of the facial artery and to provide detailed metric data regarding facial artery location with a view to helping physicians avoid iatrogenic vascular accidents during injectable treatments. Sixty specimens from 35 embalmed cadavers (24 male and 11 female cadavers; mean age, 70.0 years) and one fresh male cadaver (age, 62 years) were used for this study. In 56 cases (93.3 percent), the branches of the facial artery were observed at the vicinity of the nasolabial fold. The facial artery was located 3.2 ± 4.5 mm (mean ± SD) lateral to the ala of the nose and 13.5 ± 5.4 mm lateral to the oral commissure. It crossed the nasolabial fold in 33.9 percent of cases, and ascended within 5 mm of the nasolabial fold in 42.9 percent. The facial artery and detoured branches were found in 18 cases (30.0 percent). In the cases with detoured branches, the facial artery turned medially over the infraorbital area at 39.2 ± 5.8 mm lateral to the facial midsagittal line and 35.2 ± 8.2 mm inferior to the plane connecting the medial epicanthi of both sides. The nasojugal portion of the detoured branch traveled along the inferior border of the orbicularis oculi and then ascended toward the forehead, forming the angular artery. This detailed vascular anatomy of the facial artery will promote safe clinical manipulations during injectable treatments to the nasolabial fold and nasojugal groove.

Previous studies have revealed a variation in the origin and distribution patterns of the facial artery. However, the relationship between the facial artery and the facial muscles has not been well described. The purpose of this study was to determine the facial artery depth and relationship with the facial musculature layer, which represents critical information for dermal filler injection and oral and maxillofacial surgery. Fifty-four embalmed adult faces from Korean cadavers (36 male and 18 female cadavers; mean age, 73.3 years) were used in this study. A detailed dissection was performed, with great care being taken to avoid damaging the facial artery underlying the facial skin and muscle. The facial artery was first categorized according to the patterns of its final arterial branches. The branching pattern was classified simply into three types: type I, nasolabial pattern (51.8 percent); type II, nasolabial pattern with an infraorbital trunk (29.6 percent); and type III, forehead pattern (18.6 percent). Each type was further subdivided according to the facial artery depth and relationship with the facial musculature layer as types Ia (37.0 percent), Ib (14.8 percent), IIa (16.7 percent), IIb (12.9 percent), IIIa (16.7 percent), and IIIb (1.9 percent). This study provides new anatomical insight into the relationships between the facial artery branches and the facial muscles, including providing useful information for clinical applications in the fields of oral and maxillofacial surgery.

Background: Hyperactivity of the depressor anguli oris muscle can lead to a drooping of the mouth corner, which can give a sad, tired, or almost angry look in some patients. Botulinum toxin type A has recently been used to relax these hyperactive muscles. However, it is difficult to inject botulinum toxin type A into the depressor anguli oris muscle because its medial border overlaps with the depressor labii inferioris, and its lateral border is adjacent to the risorius, zygomaticus major, and platysma muscles. The aims of this study were to determine the topography of the facial muscles at the mouth corner and to provide critical information for determining the safest and most effective depressor anguli oris muscle botulinum toxin type A injection site. Methods: Forty-two hemifaces from Korean and Thai adult cadavers were dissected. Results: The location of the modiolus was 11.0 ± 2.6 mm (mean ± SD) lateral and 8.9 ± 2.8 mm inferior to the cheilion. The angle formed by the sagittal line passing through the modiolus (L_V) and the line connecting the modiolus and the intersection point of the lateral border of the depressor anguli oris muscle and the mandibular border (L_P2) was 44.7 ± 13.7 degrees. The angle formed by L_V and the line connecting the modiolus and the most concave point of the medial border of the depressor anguli oris muscle (L_P3) was 31.8 ± 8.5 degrees. Conclusion: These results suggest that the fan-shaped area bounded by L_P2, L_P3, and the mandibular border is the safest and most effective depressor anguli oris muscle injection site.