5 Thoracic Spine • T1–T12 are defined as the thoracic vertebrae (Table 5.1): • Kyphotic curvature: 20–40 degrees: – Apex of kyphosis at T7–T8: ∘ Pathologic kyphosis can have an apex at any level. • Articulate with their corresponding ribs at facet joints, limited range of motion: – Flexion–extension minimal at T1–T2; maximum T12–L1. – Axial rotation minimal at thoracolumbar junction; maximum at T12. • Wedge shaped with anterior height shorter than posterior height. • Width of vertebral canal is smallest in the thoracic vertebrae. • Vertebral body: – Anterior border of intervertebral foramen. – Forms articulation with ribs: ∘ Each rib articulates with two vertebral bodies: ▪ Inferior costal demifacet of superior vertebral body and superior costal facet of inferior vertebral body.
5.1 General Information
5.2 Bony Anatomy (Fig. 5.1)
Vertebrae | Associated structure |
T1 | Sternoclavicular joint |
T1–T2 | Superior angle of the scapula |
T2 | Jugular notch |
T3 | Base of the spine of the scapula |
T4 | Sternal angle of Louis |
T5–T9 | Body of the sternum |
T7 | Inferior angle of the scapula |
T8 | Level at which the inferior vena cava passes through the diaphragm |
T9 | Xiphisternal junction |
T9–L3 | Costal margin |
T10 | Esophagus passes through diaphragm |
T12 | Aorta, thoracic duct, and azygous vein pass through diaphragm |
Fig. 5.1 Lateral (a) and superior (b) views of the thoracic vertebrae. (Reproduced with permission from Baaj AA, Mummaneni PV, Uribe JS, Vaccaro AR, Greenberg MS, eds. Handbook of Spine Surgery. 2nd ed. New York, NY: Thieme; 2016.)
∘ Superoposterior edge of vertebral body.
∘ Articulates with corresponding rib of same number.
∘ Exceptions:
▪ Superior costal facet of T1 is not a demifacet:
❖ First rib only articulates with T1.
▪ T10 has one pair of complete costal facets located between the vertebral body and pedicle.
▪ T11 and T12 have one pair of complete costal facets located on the pedicles.
– Inferior costal demifacet:
∘ Inferoposterior edge of vertebral body.
∘ Articulates with head of rib below.
• Pedicle:
– Height of pedicle is double that of the width.
– Inferior notch is superior border of intervertebral foramen.
– Superior notch is inferior border of intervertebral foramen.
– Pedicle diameter is maximal at T1 and minimal at T6:
∘ Diameter gradually increases again from T6.
• Superior articular process:
– Faces posterolaterally.
– Articulates with inferior articular process of adjacent superior vertebrae.
• Inferior articular process:
– Faces anteromedially.
– Articulates with superior articular process of adjacent inferior vertebrae.
• Lamina.
• Posterior border of vertebral foramen.
• Transverse process:
– Forms the costotransverse joint.
– T1–T10 have a costal facet on transverse process that articulates with tubercle of rib.
• Spinous process:
– Long, points downward.
– Becomes level with body of vertebrae below.
5.3 Ligamentous Anatomy
• Radiate ligament of head of rib:
– Attaches head of rib to bodies and disk.
– Reinforces costovertebral joint anteriorly.
– Attaches neck of rib to transverse process.
• Superior costotransverse ligament:
– Attaches rib to transverse process of superior vertebrae.
• Intratransverse ligament:
– Fibrous cords that join adjacent thoracic vertebrae and blend with adjacent back muscles.
• Lateral costotransverse ligament:
– Attaches transverse process to tubercle of rib.
5.4 Muscular Anatomy (Tables 5.2–5.4) Vascular Anatomy (Fig. 5.2)
• Less blood supply to thoracic spinal cord than cervical and lumbar regions:
– Watershed region in midthoracic spinal cord:
∘ Poorly vascularized area.
∘ Between T4 and T9, least profuse blood supply; narrowest region of spinal canal.
