BACKGROUND Inter-foraminal implant placement poses a risk to the sublingual artery as it enters the mandibular midline lingual foramen. Lack of consensus on the source of this artery poses a dilemma to surgeons during management of haemorrhagic episodes. Determination of the exact source of this artery is therefore pivotal. METHODS This was a cross-sectional descriptive study involving 34 adult human cadavers. The facial and lingual arteries were followed from the external carotid artery to determine whether they terminated as the sublingual artery. Statistical significance tests were done using the Mann-Whitney U test and Pearson product-moment correlation. RESULTS There were 30 (88.2 %) males and 4 (11.8 %) females (male/female = 15:2) aged between 25 and 40 years. The origin of the sublingual artery was mainly from the lingual artery (73.5 %), the submental artery (17.6 %), or an anastomotic branch from the two arteries (8.9 %). The mean distance between the mandibular midline lingual foramen (MMLF) and the inferior border of the mandible was 15.58 mm (range 11.03-19.62 mm). The mean thickness of the mandible at the level of the MMLF was 10.89 mm (range 8.00-12.91 mm). No statistically significant difference was found between the two genders with regard to the morphometric measurements. CONCLUSIONS The sublingual artery that enters the MMLF was found to be the sublingual artery as either a branch of the lingual artery (73.5 %), the submental artery (17.6 %) or an anastomosis of the lingual and submental arteries (8.9 %).