Details of Thoracic and Lumbar Spine for Neurology and Neurosurgery residents along with blood supply

1. THORACO-LUMBAR SPINAL
ANATOMY
DR SAMEEP KOSHTI

15. • In the thoracic spine,
• the ventral primary ramus
• the posterior intercostal nerve.
• joins the intercostal neurovascular bundle of the like-named rib.
• E.G.
• 9th thoracic spinal nerve exits through the T9-10 foramen and gives rise to the ninth posterior intercostal
nerve, which joins the intercostal bundle beneath the ninth rib.
• In the lumbar spine,
• Bifurcation into ventral and dorsal primary rami occurs
• at the level of the intervertebral disc.
• The lumbar ventral primary rami
• continue along the oblique course of the spinal nerve and make up the lumbar and lumbosacral plexi.

16. NERVE ROOT ANOMALIES
• Anomalies of nerve roots are relatively common, occurring in over
10% of nerve roots studied.
• Intradural connections, or
• conjoined roots, are more common than
• extradural anastomoses, which often have no demonstrable neural
connection

18. VASCULAR SUPPLY
• The lower cervical (C6, C7) and upper thoracic (T1, T2) spine receives
• supply from costocervical branches of the subclavian artery.
• Segmental vessels are named differently (from DESCENDING AORTA)
• In the thoracic spine (3-11)
• termed posterior intercostal arteries;
• twelfth rib
• subcostal artery.
• Lumbar segmental arteries are termed
• lumbar arteries

21. • The segmental arteries have three major branches.
• Ventral to the neural foramen,
• each segmental artery branches into a
• dorsal (or middle) and a
• lateral branch.
• One or more spinal (or medial) branches will arise either from
• the parent segmental artery, the dorsal branch, or
• the lateral branch. The

23. Blood supply of spinal cord
• Branches of this arterial network
• broadly divided into two systems.
• On the surface of the spinal cord (White matter tracts)
• the pial arterial plexus (or coronae radiatae or vasa corona),which connects the anterior and posterior
spinal arteries, supplying peripheral white matter tracts.
• The gray matter of the spinal cord, (including both dorsal and ventral horns)
• is principally supplied by central arteries (sulcal branches) from the anterior spinal artery.
• cervicothoracic area
• multiple branches of the vertebral arteries, the deep cervical artery, and the ascending
cervical artery.
• The intermediate, or midthoracic zone (T4-T8)
• has a sparser arterial supply.
• Supplied by radiculomedullary vessels from the segmental system that are inconsistent in
number and size;
• often only one major radiculomedullary vessel supplies this zone.

24. Contd…
• The lower, or thoracolumbar zone (T9-conus),
• The principal radiculomedullary artery to this zone is known as the artery of
Adamkiewicz;
• The artery typically arises at a variable level between the ninth intercostal artery and second lumbar
artery (in 85% of cases),
• most commonly on the left side (in approximately 75% of cases)