Abstract
Several anatomic landmarks, such as the internal jugular vein and the omohyoid muscle, are used to guide dissection of the upper neck. In the present report, we describe the case of an abnormal relationship between the internal jugular vein and the omohyoid muscle.
A 70-year-old woman was referred to our hospital because of pain in the left mandibular molar region. Physical examination revealed no abnormal finding. There were also no abnormalities in the skeletal structure. She was given a diagnosis of a primary intra-osseous carcinoma of the left mandible with cervical lymph-node metastases on the left side.
The patient underwent segmental resection of the left mandible and left lateral functional neck dissection, followed by reconstructive surgery with a rectus abdominis muscle flap.
During dissection of the upper and middle neck, we observed that the internal jugular vein contained a foramen through which the accessory nerve passed at the level of the hyoid bone. In addition to this anatomical variation, the internal jugular vein was located above the omohyoid muscle and separated into anterior and posterior branches. The inferior belly of the omohyoid muscle passed between these venous branches. Both branches of the internal jugular vein and the omohyoid muscle were preserved.
