They are continuous with the periapical tissues through the apical foramen or foramina. Impaired venous outflow is often caused by a hypoplastic jugular foramen. Shortly after a spinal nerve exits the intervertebral foramen. The maxillopalatine suture also includes a posterior palatine foramen. It exits the orbit through the anterior ethmoidal foramen. Obstruction can result in jugular foramen syndrome. The vertebral foramen is large and triangular. They then proceed superiorly, in the transverse foramen of each cervical vertebra. It exits the pelvic cavity through the lesser sciatic foramen. It forms the upper edge of the obturator foramen. The greater sciatic foramen is an opening (foramen) in the posterior human pelvis. Fibers cross over to and join the vagus nerve in the jugular foramen. In front it is limited by the posterior margin of the obturator foramen. Together, these enclose the vertebral foramen, which contains the spinal cord. There are two midline skull landmarks at the foramen magnum.