the spinal cord at the thoracic level. The spinous process is long, triangular on coronal section, directed obliquely downward, arising from the lamina and ending in a tuberculated extremity. These processes overlap from the fifth to the eighth, but are less oblique in direction above and below. The superior articular processes are thin plates of bone projecting upward from the junctions of the pedicles and laminae; their articular facets are practically flat, and are directed backward and a little lateralward and upward. The inferior articular processes are fused to a considerable extent with the laminae, and project but slightly beyond their lower borders; their facets are directed forward and a little medialward and downward. The transverse processes arise from the arch behind the superior articular processes and pedicles; they are thick, strong, and of considerable length, directed obliquely backward and lateralward, and each ends in a clubbed extremity, on the front of which is a small, concave surface, for articulation with the tubercle of a rib. Individual thoracic vertebrae First thoracic vertebra (T1) The first thoracic vertebra has, on either side of the body, an entire articular facet for the head of the first rib, and a demi-facet for the upper half of the head of the second rib. The body is like that of a cervical vertebra, being broad, concave, and lipped on either side. The superior articular surfaces are directed upward and backward; the spinous process is thick, long, and almost horizontal. The transverse processes are long, and the upper vertebral notches are deeper than those of the other thoracic vertebrae. The thoracic spinal nerve 1 (T1) passes out underneath it. Second thoracic vertebra (T2) The thoracic spinal nerve 2 (T2) passes out underneath it. The second thoracic vertebra is larger than the first thoracic vertebra Third thoracic vertebra (T3) The thoracic spinal nerve 3 (T3) passes out underneath it. Fourth thoracic vertebra (T4) The fourth thoracic vertebra, together with the fifth, is at the same level as the sternal angle. The thoracic spinal nerve 4 (T4) passes out underneath it. Fifth thoracic vertebra (T5) The fifth thoracic vertebra, together with the fourth, is at the same level as the sternal angle. The human trachea divides into two main bronchi at the level of the 5th thoracic vertebra, but may also end higher or lower, depending on breathing. The thoracic spinal nerve 5 (T5) passes out underneath it.