Download File

Applied anatomy and examination of the Back
Week 27 LOs
Understand the concepts & associated principles, functional & clinical applications of:
4. The significance of the valveless “internal vertebral venous plexus”.





Spinal veins form venous plexuses both inside and outside the vertebral column, the internal
venous plexus and the external venous plexus
the internal venous plexus consists of a dense network of thin-walled, valveless veins which
surround the dura mater
veins from the vertebral body (basivertebral veins) drain primarily into the internal vertebral
plexus
flow may occur in either direction
communication with venous plexuses around pelvic viscera provides a pathway for tumour
spread (e.g. from the prostate gland)
5. The vulnerability of the arterial supply of the spinal cord (noting the sites of poor anastomoses).


three longitudinal arteries which descend from level of foramen magnum:
 anterior spinal artery
– (x1) from vertebral arteries
 posterior spinal arteries
– (x2) paired, from vertebral arteries
 supplemented at variable levels by
anastomoses with radicular arteries
 spinal arteries are branches of the:
– vertebral and ascending cervical
arteries in the neck
– posterior intercostals arteries in
the thoracic region
– subcostal and lumbar arteries in
the abdomen
– iliolumbar and lateral and medial
sacral arteries in the pelvis
 spinal arteries enter the IV foramina and
divide mostly into terminal radicular
arteries distributed to the dorsal and
ventral roots of the spinal nerves and their
coverings
 these are important particularly in lower
thoracic region where anterior spinal artery
almost non-existent
some radicular arteries continue as irregularly spaced medullary segmental arteries that
anastamose with arteries of the spinal cord
6. The sites, mechanism and effects of lumbar intervertebral disc “prolapse”.

Herniation/protrusion of the nucleus pulposus through the annulus fibrosus is a wellrecognised cause of lower back pain
Sites:
 95% occur at the L4/L5 or L5/S1 levels
 usually occur posteriorly where annulus fibrosis is relatively thin and poorly supported by
either the posterior or anterior longitudinal ligaments
 in young people the IV discs are turgid and consist of approximately 90% water
Mechanism:
 violent hyperflexion of the vertebral column may result in IV disc rupture and fracture of
adjacent vertebrae
 flexion of the vertebral column causes compression anteriorly and stretching or tension
posteriorly, pushing the nucleus pulposus posteriorly towards the thinnest part of the
annulus fibrosis
 if degeneration of the posterior longitudinal ligament and wearing of the annulus fibrosis has
occurred, the nucleus pulposus may herniate into the vertebral canal and compress the
spinal cord or the nerve roots of the chorda equina
Effects:
 posterolateral herniated disc is more like to be symptomatic due to proximity of spinal nerve
roots
 localized back pain is caused by pressure on the longitudinal ligaments and periphery of the
annulus fibrosis and from local irritation resulting from local inflammation resulting from
chemical irritation by substances from the ruptured nucleus pulposus
 chronic pain from the spinal nerve roots being compressed is referred to the dermatome
supplied by that nerve
What structures are endangered by an intervertebral disc protrusion?
• Dorsal & ventral roots
• Dorsal root ganglion
• Spinal nerves
• Feeder (radicular) vessels