RESUMEN
Marginal mandibular nerve is a motor branch of facial nerve which supplies the muscles of the peri oral region. Surgical and cosmetic procedures might cause injury to this nerve resulting in functional loss and cosmetic imperfection. This study on the anatomical relation of marginal mandibular nerve, with respect to the lower border of mandible and facial artery, will benefit maxillofacial and plastic surgeons in its safe identification, hence preserving the functional integrity of this significant branch of facial nerve. Careful dissection was done on one hundred [100] hemi-faces of adult cadavers in Forensic and Anatomy departments of King Edward Medical University, Lahore from September 2009 to March 2010. Cadavers with scar, disfigurement or putrefaction in face and/or neck region were excluded. In 100 hemi faces, Marginal mandibular nerve present singly above the lower border of mandible was seen in 74% of cases. Marginal mandibular nerve having two rami, both located above the lower border was seen in 14% of cases. Two rami of marginal mandibular nerve, one present above and one below the lower border of mandible was seen in 6% of cases. Three rami of marginal mandibular nerve, two rami above and one below lower border of mandible were present in 6% of cases. In our population marginal mandibular nerve normally exits from anterior border of parotid gland above the lower border of mandible. When two or more rami of nerve are present; chances of lower most rami of nerve coursing below the inferior border of mandible increases. The nerve rami are present superficial to facial artery. It is at risk of iatrogenic injury overlying and anterior to massetter muscle where the nerve lies superficially underneath a thin layer of superficial musculoaponeurotic system