Spine Anatomy

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Denis Model for Columns of the Spine

Anterior	Middle	Posterior
ALL + first half of VB	Second half of VB + PLL	Posterior arch with ligaments

Ligament	Image	Facts
Apical	ㅤ	ㅤ
Alar	ㅤ	- connect dens to clivus - injured in AOD (along tectorial membrane)
Transverse (part of Cruciate ligament)	ㅤ	- allows neck rotation - inserts on medial tubercule of C1 lateral mass - rupture → C1 onto C2 translocation - holds odontoid aspect to posterior aspect of C1 anterior arch - if this is violated, need to do a C1-C2 fusion, no odontoid screw is not enough

Tract	Functions	Notes
Posterior Columns	fine touch, vibration, proprioception, stereognosis, deep pressure	CG (T6): Cuneus: C spine to T6, Gracilius: below T6
Anterior spinothalamic	crude light touch (non-discriminiative)	- slow Aδ and C fibers - course: ascend 1-2 segments → synapse in Lissauer’s tract → ascend and terminate → VPN
Lateral spinothalamic	pain, temperature	- rapid fibers - course: ascend 1-2 segments → synapse in Lissauer’s tract → ascend and terminate → VPN
Spinotectal	ㅤ	ㅤ
Dorsal spinocerebellar	ㅤ	ㅤ
Ventral	ㅤ	ㅤ

Pain receptors

C-fiber nociceptors: slowly conducting unmyelinated axons

prolonged firing (pain) → release of glutamate that binds to NMDA receptors → spinal cord becomes hypersensitive to all of its inputs

A-delta nociceptors: thinly myelinated axons

Group 1b fibers

afferent fibers from Golgi organs at junction between skeletal muscle and tendons

Golgi tendon reflex
* 1B fibers synapse with 1b inhibitors interneurons → inhibitory connections to hmonymous motor neurons

Blood supply of cervical spinal cord

angle drawn from center of S1 endplate and line that joins center of femoral heads to center of S1 endplate