Talk:Spinal cord
From Academic Kids
I changed
- The vertebral column consists of 5 segments. From top to bottom those are: the cervical verterbrae, the thoracic, the lumbar, the sacrum and the coccyx.
to read
- The vertebral column consists of vertebrae described as belonging to 5 groups (called segments). These segments are (in order from top to bottom): the cervical, thoracic, and lumbar vertebrae, and the sacrum and coccyx.
My reasoning is based on my understanding that at, for instance, the L/T boundary, the morphologies of L1 and T12 differ less than do those of L1 and L5, or of T1 and T12. I'm not clear whether the differences (in morphology or i suppose in function) between L1 and L2, and between T11 and T12, are 99% of the difference between L1 and T12, or 50% of that difference. I.e., i've no idea just how artificial the division is, but i feel pretty safe in assuming that the people who are skilled at distinguishing them think of them (not bcz they are stupid, but bcz it is efficient to do so and harmless among specialists) as at least a little more, and probably a lot more, distinct than they objectively are.
I don't suggest the terminology is counterproductive, but IMO it's worth maintaining an awareness that, e.g., we might talk abt T1 thru T13 and L1 thru L4 if a different anatomical pioneer had published first. I think there are well documented effects of the intellectual confusion between
- useful terminology and
- "essences" that could mean e.g. species are so "essentially" different as to make evolution absurdly implausible.
Even tho i can't [big wink] be wrong about this, even if i were, i would argue for saying explicitly that there are objective reasons of morphology or embryology or whatever specific area(s) of biology for choosing 5 segments with those boundaries, rather than 6 or 4 groups, or 5 with different boundaries, and giving numeric estimates of how distinctive each of the various boundaries is - even if it's not feasible to get us lay folk to understand what those objective reasons are, even with a specialized Wikipedia page on that specific topic. --Jerzy 23:57, 2003 Oct 13 (UTC)
I didn't tamper with "the level of L3/L4", but i wished i knew enuf to clarify it: is that the gap between L3 and L4, or is it the whole length of L3 and L4? --Jerzy 23:57, 2003 Oct 13 (UTC)
Differences between vertebrae
There are several distinguishing features which can enable any anatomist to distinguish between a vertebrae from one section of the body to another. The distinctions are not artificial.
All cervical vertebrae, except for C6 and 7 have vertebral canals through which passes the vertebral artery. They also have long spinous processes.
All thoracic vertebrae have ribs and the procesees at which ribs attach. I could go into these, but it's rather long and complicated. No vertebral canals. About 1/1000 people have a cervical rib, which is a rib that articulates with the C7, but this is uncommon, and can possibly be pathological (as in thoracic outlet syndrome)
Lumbar vertebrae havev large bodies, no ribs attached, and large transverse processes.
Hope this helps
DMC MS-1
