T Nation

Most Disk Herniatons are in the T-Spine

More than 75 percent of disk herniations occur below T8. The peak is at T11-12 where there is greater spinal mobility. Central protrusions are the mast common.

Okada Y, Shimizu K, Ido K, Kotani S (1997) Multiple thoracic disc herniations: case report and review of0the literature. Spinal Cord, 35: 182-186. <now I see the title only talks about T-spine herniations. While I didn’t read the original study, since the page quoting doesn’t explicitly say that it concerns only the T-spine etc etc as such, I guess the study is invalid for the subject. Sorry>

Can anyone explain why is it ok to flex and rotate the T-Spine but not the lumbar?
Thanks, Vlad

I was under the impression that the majority of disc herniations occur at L4-L5? Hmmm

It should not be desirable to round anywhere in the spine.

The loading associated with rounding that places Lumbar discs at risk is just the same for all of the Vertebrae.

Well it’s never really ok to apply two shearing forces at the same time on any part of the spine.

You have what’s called facet joints along the back of your spine. The ones in the lumbar are oriented mainly straight up and down… so rotation really isn’t what they were designed for. The ones in your thoracic are at about a 60 degree angle, so they handle rotation forces better. The reason most thoracic herniations occur there is because of the thoraco/lumbar junction where your lordosis turns into a kyphosis and the force isn’t transferred as well because of motion restrictions in different planes.

Ironabrams: Overall the research shows that L4-L5 is the most herniated. The reason is since L5-S1 is less mobile the segment above has more motion occurring at it to compensate. Plus it has to do with the way the lumber vertebrae are shaped. The bodies are thicker in the front than the back so the disc is easier pushed towards the back and herniates easier.

Amount of weight bearing plays a role too. It is as grrrsauce says, rotating the spine in spinal flexion = compression and shearing = very common mechanism of injury for the back. I have seen my fair share of disc injuries in the neck secondary to weight training because of that same rotation in a flexed position.

I haven’t seen any numbers or case studies on this mechanism of injury in people lifting, exercising or stretching. I’m not involved with strongman events.

I have seen tons on manual laborers picking up heavy objects and twisting, people shoveling snow and nurses moving patients.

[quote]IrishMarc wrote:
It should not be desirable to round anywhere in the spine.

The loading associated with rounding that places Lumbar discs at risk is just the same for all of the Vertebrae.[/quote]

You are discounting the structural differences in vertebra at different spinal levels, as one of the other posts discusses. If you’re going to put the spine into loaded flexion, at least the thoracic vertebra have more bony support than the lumbar.