In common with the other vertebrae, the thoracic vertebrae have a body which bears the weight of
the column above, a spinal canal formed by the pedicles and laminae, a spinous process and two
transverse processes. On T1, T11 and T12 vertebrae there are facets for articulation of the
corresponding ribs. All other ribs articulate with their own vertebra and the vertebra above. Each
rib also articulates with the transverse process of its own vertebra. Each of these vertebral bodies
therefore has superior and inferior hemifacets. The spinous processes of the thoracic vertebrae
are inclined sharply downwards. The articular facets on the vertebral arches lie almost in the
coronal plane and so permit a small amount of rotation.
The upper ten ribs articulate anteriorly either directly with the sternum through their costal
cartilages (true ribs), or through a fused cartilage (false ribs). The eleventh and twelfth ribs do
not articulate anteriorly (floating ribs). The first rib is flattened above and below. Its anterior
cartilage is fused to the manubrium forming a rigid ring, the thoracic inlet. During respiration the
thoracic inlet is fixed, in part by muscles such as scalenus anterior anchoring it to the cervical
column. The second to seventh ribs articulate anteriorly with the sternum through synovial joints.
Posteriorly the ribs articulate with the vertebral bodies (the head of the rib) and the transverse
processes (tubercle of the rib). These articulations allow the ribs to move upwards and outwards
during inspiration, so increasing both the anterior - posterior and right - left diameters of the
thorax. These movements, referred to as pump-handle and bucket-handle movements, increase
the thoracic diameters due to the downward course of the rib and to its curvature.
The sternum is formed by the manubrium, body and xiphisternum. The manubrium is notched on
its superior margin forming the jugular notch. The upper lateral angles are notched for
articulation with the clavicles. The first ribs articulate immediately below the sternoclavicular
joints. The second rib articulates at the manubriosternal joint. Because of the angle at which the
manubrium and body meet a ridge is formed, the sternal angle or angle of Louis. This joint is in
the same plane as the bottom of the fourth thoracic vertebra.
| 1. Sternocleidomastoid |
| 2. Jugular notch |
| 3. Clavicle |
| 4. Angle of Louis |
| 5. Xiphisternum |
| 6. Costal margin |
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