Unusual branching pattern of external carotid artery in the left carotid triangle.

During the routine dissection of the neck for the first MBBS students, we have found the abnormal branching of the external carotid artery in the carotid triangle. The external carotid artery is a terminal branch of the common carotid artery arises at the level of superior border of the thyroid cartilage in the carotid triangle. It supplies the structures of head and neck regions by its eight branches. The knowledge of variations is very important for the general, head & neck, ENT and oncosurgeons, to avoid unforeseen complication in the form of bleeding by injuring the abnormal arteries. It is also important for the vascular surgeons and radiologists while performing the procedures on the arteries.

Trifurcation of External Carotid Artery and Variant Branches of First Part of Maxillary Artery.

The external carotid artery normally divides into two terminal branches at the level of the neck of the mandible. The terminal branches are usually the superficial temporal and maxillary arteries. The maxillary artery is described to be in three parts in relation to the lateral pterygoid muscle as the mandibular (first), pterygoid (second) and the pterygopalatine (third) parts. The second part passes behind the muscle. The branches that arise from the first part of the maxillary artery are the deep auricular, anterior tympanic, the middle meningeal, accessory meningeal and inferior alveolar arteries. The middle meningeal artery normally arises at the lower border of lateral pterygoid muscle from the first part of maxillary artery. It then ascends upwards, passes between the two roots of the auriculotemporal nerve and enters the foramen spinosum in the base of skull. During routine dissection of a male cadaver in the department of anatomy while teaching medical students variations were observed in the termination of the external carotid artery on the right side. The artery gave three branches at the termination, superficial temporal, maxillary and between the two the middle meningeal artery was seen arising close to the end of the external carotid artery. The middle meningeal artery did not pass between the two roots of the auriculotemporal nerve. The branches of first part of maxillary artery were variable. The deep auricular branch was absent and its territory may have been supplied by the posterior auricular and anterior auricular arteries. The anterior tympanic and accessory meningeal arteries arose from the middle meningeal artery. There were two inferior alveolar arteries 1.5 cm apart arising from the first part of maxillary artery. The first artery went to the mandibular canal along with the inferior alveolar nerve. The second artery accompanied the lingual nerve to the last molar tooth. Probably this artery may have been an additional supply to the gingiva around the last molar tooth. The other variations that were noted were the absence of mylohyoid branch from the inferior alveolar artery. To the best of our knowledge these variations in the arteries have not been previously reported.