Sixth thoracic vertebra (T6) The thoracic spinal nerve 6 (T6) passes out underneath it. Seventh thoracic vertebra (T7) The thoracic spinal nerve 7 (T7) passes out underneath it. Eighth thoracic vertebra (T8) The eighth thoracic vertebra is, together with the ninth thoracic vertebra, at the same level as the xiphisternum. The thoracic spinal nerve 8 (T8) passes out underneath it. Ninth thoracic vertebra (T9) The ninth thoracic vertebra may have no demi-facets below. In some subjects however, it has two demi-facets on either side; when this occurs the tenth doesn't have facets but demi-facets at the upper part. The thoracic spinal nerve 9 (T9) passes out underneath it. The xiphisternum (or xiphoid process of the sternum) is at the same level in the axial plane. Tenth thoracic vertebra (T10) The tenth thoracic vertebra has an entire articular facet (not demi-facet) on either side, which is placed partly on the lateral surface of the pedicle. It doesn't have any kind of facet below, because the following ribs only have one facet on their heads. The thoracic spinal nerve 10 (T10) passes out underneath it. Eleventh thoracic vertebra (T11) In the eleventh thoracic vertebra the body approaches in its form and size to that of the lumbar vertebrae. The articular facets for the heads of the ribs are of medium size, and placed chiefly on the pedicles, which are thicker and stronger in this and the next vertebra than in any other part of the thoracic region. The spinous process is short, and nearly horizontal in direction. The transverse processes are very short, tuberculated at their extremities, and do not have articular facets. The thoracic spinal nerve 11 (T11) passes out underneath it. Twelfth thoracic vertebra (T12) The twelfth thoracic vertebra has the same general characteristics as the eleventh, but may be distinguished from it by its inferior articular surfaces being convex and directed lateralward, like those of the lumbar vertebrae; by the general form of the body, laminae, and spinous process, in which it resembles the lumbar vertebrae; and by each transverse process being subdivided into three elevations, the superior, inferior, and lateral tubercles: the superior and inferior correspond to the mammillary and accessory processes of the lumbar vertebrae. Traces of similar elevations are found on the transverse processes of the tenth and eleventh thoracic vertebrae. The thoracic spinal nerve 12 (T12) passes out underneath it. Other animals In other animals