Alignment Sagittal plane alignment normal thoracic kyphosis average 35° login to view 1 more bullet Osteology Vertebral prominens the long, prominent spinous process found at C7 Costal facets articulation between ribs and vertebral segments present on all vertebral bodies and transverse processes from T1 to T9 articulation with ribs leads to increased rigidity of thoracic spine (most rigid in axial skeleton) Vertebral body size increases progressively from T1 to T12 Spinal canal dimension varies from T1 to T12 Motion The orientation of the facet (zygapophyseal) joints determines the degree and plane of motion at that level varies throughout the spine to meet physiologic function cervical spine (C3-7) planes login to view 2 more bullets function login to view 1 more bullet thoracic spine planes login to view 3 more bullets function login to view 2 more bullets lumbar spine plane login to view 2 more bullets function login to view 2 more bullets Thoracic Pedicle Anatomy Pedicle diameter the pedicle wall is twice as thick medially as it is laterally T4 has the narrowest pedicle diameter (on average) T7 can be irregular and have a narrow diameter on the concave side in AIS T12 usually has larger pedicle diameter than L1 Pedicle length pedicle length decreases from T1 to T4 and then increases moving distally in the thoracic spine T1: 20 mm T4: 14 mm (shortest pedicle) T10: 20 mm Pedicle angle transverse pedicle angle varies from 10° (mid-thoracic spine) to 30° (L5) sagittal pedicle angle 15-17° cephalad for majority of the thoracic spine neutral (0°) for lumbar spine except L5 (caudal) Erector Spinae Muscles Characteristics function to extend the trunk located dorsal to the vertebral column innervated by dorsal rami of spinal nerves Erector spinae muscles include spinalis most medial origin and insertion: spinous process to spinous process longissimus intermediate origin and insertion: transverse process to transverse process iliocostalis most lateral origin: ilium and ribs insertion: ribs and transverse process Surgical Approaches Surgical approaches for thoracic disc herniation laminectomy/hemilaminectomy transpedicular costotransversectomy lateral extracavitary anterior intracavitary thoracotomy video-assisted thoracoscopic surgery (VATS)