Anatomical variation in arterial supply of the mandible with special regard to implant placement.

The aim of this study was to explore the anatomical variation of the sublingual artery in relation to the mandible, and provide preoperative information to avoid hemorrhagic complications of implant placement. One hundred adult human cadavers injected with red latex were examined. The main arterial supply to the anterior mandible is the sublingual artery as a branch of the lingual or submental artery. This artery exhibited three notable branches, termed ascending, middle and descending. In 73% of cases the sublingual artery originated from the lingual artery to give ascending (72%), middle (98%) and descending (54%) branches. In the remaining 27 cases the sublingual artery originated from the submental artery, giving ascending (69%), middle (98%) and descending (50%) branches. It was possible to identify anastomotic patterns between the sublingual and inferior labial arteries in 52%, sublingual and submental arteries in 40%, and submental and inferior labial arteries in 54% of cases. Of the branches supplying the floor and gingival mucosa of the anterior mandible, mucosal branches of the sublingual were found in the territory of the lateral incisor in 72%, canine in 62%, and first premolar in 81% of cases. Disruption of these anastomoses by implant placement could cause life-threatening hemorrhages. These data should prove useful in the placement of mandibular implants.

The ansa cervicalis revisited.

Recurrent laryngeal nerve paralysis represents a major complication in oesophageal cancer surgery. Nerve-muscle transplantation to the paraglottic space after resection of the recurrent laryngeal nerve with the ansa cervicalis (AC) has recently become the procedure of choice. The aim of this study was to investigate the anatomical variations of AC in order to avoid iatrogenic injuries and facilitate surgical procedures. We examined 100 adult human formalin-fixed cadavers. The ansa cervicalis showed a great degree of variation regarding origin and distribution. The origin of the superior root of AC was found to be superior to the digastric muscle in 92% of the cases. Its vertical descent was found to be superficial to the external carotid artery in 72% and superficial to the internal carotid artery in 28% of the specimens. The inferior root of AC was derived from the primary rami of C2 and C3 in 38%, from C2, C3 and C4 in 10%, from C3 in 40% and from C2 in 12% of the cases. The inferior root passed posterolaterally to the internal jugular vein in 74% and anteromedially in 26% of the cases. The roots of AC were long (70%) or short (30%), and the union between the two roots was situated inferior or superior to the omohyoid. Not only is knowledge of the anatomy of the ansa cervicalis important for nerve grafting procedures, but surgeons should be aware of AC and its relationships to the great vessels of the neck in order to avoid inadvertent injury during surgical procedures of the neck.